Industrialization and urbanization affect the environment directly, and water is one of the prima... more Industrialization and urbanization affect the environment directly, and water is one of the primary natural resources which are affected significantly. With rapid development of science of nanotechnology, the use of nanomaterials in environmental applications, especially water treatment, has attracted the scientific community in the last decades. Nanomaterials have unique properties, for example, surface-to-volume ratio, quantum effect, low band-gap energy, etc., which give extra features in catalytic performance.
Nanotechnology-Based Industrial Applications of Ionic Liquids, 2020
Nanoparticles (NPs) have been applied in the field of nanotechnology and are an attraction in con... more Nanoparticles (NPs) have been applied in the field of nanotechnology and are an attraction in consideration of the scientific community because of their potential and wide applications in various areas such as electronic devices, biomedical science, and catalysis. The synthesis of NPs usually in the range of 1–100 nm through the green route using different biological or green technique entities has been actively followed as an alternative approach for the self-assemble atoms to form nuclei of nanoparticles. However, the processes for the synthesis of nanoparticles are influenced by several parameters like solution pH, morphological structure of reactants, reaction time, and temperature. Also, the size, shape, and geometry are the significant characteristics of NPs. Nanostructured materials can also be synthesized through different physical and chemical processes. However, biological synthesis is more favorable due to environment-friendly and green chemistry-based technique. This chapter addresses a brief overview of the recent techniques in the development and synthesis of nanoparticles via the biological method and their forthcoming applications for sustainable environmental application. The effects of the different parameters, as mentioned above, have also been discussed in detail with NP formation mechanisms using plant extracts associated with the geometry or morphology, spectral response and specific particle sizes, and explicit functionality for antimicrobial activity. The effect of NPs on antimicrobial activity is based on the inhibition properties of gram-positive and gram-negative bacteria.
Handbook of Nanomaterials for Wastewater Treatment, 2021
Abstract Water is an essential component for all living bodies starting from agriculture, industr... more Abstract Water is an essential component for all living bodies starting from agriculture, industry, to domestic cares. Only 1% of water is easily accessible of 2.5% freshwater in the world, although the world has 70% of water. Hence it is necessary to recycle the water to meet the necessity of the world. Moreover, many process industries are also discharging wastewater directly to the environment without any proper treatment, and this wastewater contains enormous complex refractory molecules that are not easy to degrade through conventional biological methods. Therefore advanced techniques for wastewater treatment are very much necessary to fulfill the ever-increasing requirements of the increasing population. Nanomaterial-based treatment techniques are found to be economical because of the reusability of the catalyst. Recently, the magnetic nanoparticles for wastewater treatment have changed the interest of the scientific community because the nanomaterials possess excellent properties—the synthesis process is simple, high stability, high adsorption capacity, can be regenerated easily, and recycled for several times without losing its properties. Among these various magnetic materials, the ferrite nanoparticles, which are nothing but the transitional metal oxides with spinel structures, have gained the topmost position in terms of wide applications because they have very simple chemical composition, excellent magnetic properties, and immense applications for wastewater treatment, catalyst, and electronic devices for biomedical applications. This chapter presents a critical account of the literature on synthesis of magnetic nanomaterial and its applications for effective degradation of bio-recalcitrant organic compounds appearing in discharges of chemical and process industries.
Graphical abstract Reaction Mechanism and Formation of Fine Emulsion due to Physical Effects of C... more Graphical abstract Reaction Mechanism and Formation of Fine Emulsion due to Physical Effects of Cavitation in Liquid-Liquid Heterogeneous System.
The emerging contaminants in wastewater discharged from numerous chemical process industries, pha... more The emerging contaminants in wastewater discharged from numerous chemical process industries, pharmaceutical industries, textile, and wineries have attracted the attention of the scientific community due to their toxicity and persistence in the environment. The conventional techniques are incompetent to treat many of such recalcitrant toxic pollutants. To achieve high mineralization, advanced oxidation processes (AOPs) are found to be more efficient for the degradation of these organic pollutants without producing secondary pollutants with no/less amount of sludge. The primary oxidation agents for AOPs are in-situ generated free radicals, which are highly reactive and effective oxidants for degrading any type of organic molecules present in the wastewater. In the past decades, the combination of AOPs or simultaneous application of more than one AOP has been investigated extensively for wastewater treatment and these hybrid-AOPs have been reported to be beneficial for high-level mineralization of organic pollutants. This paper presented the characteristics, properties and influence of parameters in sono-photo-ferrioxalate system. The primary operating parameters in sono-photo-ferrioxalate system that affect the kinetics are defined as the solution pH, temperature, molar ratio of Fe3+/C2O42-, H2O2 concentration, source of light, ultrasound intensity, dissolved gases, and size of cavitation bubble. In this process, several oxidizing radicals are generated such as HO•, HO2•, C2O4•-, CO2•- and O2•- which are also responsible for degradation. In this review, we have mainly addressed the degradation of recalcitrant pollutants using the sono-photo-ferrioxalate system and a critical analysis of process parameters that influence mineralization efficiency.
In this study, the aim was to explore the effectiveness of the UV/H2O2 photolysis (UVP) process i... more In this study, the aim was to explore the effectiveness of the UV/H2O2 photolysis (UVP) process in terms of antimicrobial activity reduction and increasing the mean oxidation number of carbon (MONC) under the degradation of chloramphenicol (CHPL) drug. CHPL degradation kinetics and the effects of foreign anions on CHPL degradation were explored in this study. The order of the inhibition effect was found as Cl− > NO3− > HCO3− due to their different in HO• radical scavenging capacity. A pseudo-first-order model for CHPL degradation was well established, and the rate constant (kobs) was 2.93 × 10−2 min−1 (R2 = 0.98) in UVP. Thirteen intermediate products were detected in MS-chromatogram and were identified through different proposed degradation pathways. The cleavage of the amide side chain in CHPL was more effective in CHPL degradation due to an electrophilic attacks by HO. radicals on it. The inactivation rates of E. coli were decreased due to the reduction of -NO2 group into -...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of the Taiwan Institute of Chemical Engineers, 2019
Abstract In this study, an attempt was made to investigate the mechanistic insight to identify th... more Abstract In this study, an attempt was made to investigate the mechanistic insight to identify the links between enzymatic and sonolysis processes through degradation mechanism. Experimental results revealed that ultrasound and cavitation increase the number of collision in enzymatic process through intense convection in the medium generated by transient cavitation, and enhances degradation efficiency by increasing interaction between enzyme and organic molecules. The formation of pH· radicals in Bisphenol-A degradation is significant and it needs external binding agent such as polyethylene glycol (PEG) to prevent the blocking of reactive sites of enzymes. On the other hand, Ciprofloxacin is susceptible to enzyme, and thus the degradation enhancement is not much significant in sono-enzymatic process. The highest degradation rates at optimum condition of pH 7.0 and 25 °C were 66.52% and 68.41% for Bisphenol-A and Ciprofloxacin, respectively. The antimicrobial activity test and the LCMS results revealed that the intermediates (acetic acid, ethyl alcohol and other products with –OH group) formed during sono-enzymatic reaction are less toxic as compared to that formed in enzymatic process. This essentially means that the enzymatic process initiates the degradation reaction and ultrasound helps towards complete mineralization by degrading the intermediates. To the best of our knowledge, this is the first report on detailed degradation mechanism of Bisphenol-A and Ciprofloxacin using enzymatic and sono-enzymatic processes.
Asia-Pacific Journal of Chemical Engineering, 2019
The present investigation reports the effect of thiocyanate-based ionic liquid (IL) on the therma... more The present investigation reports the effect of thiocyanate-based ionic liquid (IL) on the thermal dehydrogenation of amine boranes. Fifteen ILs based on thiocyanate anion comprising cations from imidazolium, pyrrolidinium, and ammonium family were screened by a priori prediction of infinite dilution activity coefficient using the quantum chemical-based conductor-like screening model segment activity coefficient method. The IL with the highest predicted solubility of amine boranes converged to 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) that was then used for the dehydrogenation reaction. In the IL medium, ammonia borane (AB) and ethylene diamine bisborane (EDAB) were found to produce~1.64 equivalent of hydrogen with an induction period of 60 min and~2.37 equivalent of hydrogen having an induction period of 30 min, respectively. It was observed that the mixture of AB and EDAB in [EMIM][SCN] produced prolonged induction period of 210 min. After 240 min, the mixed amine boranes only produce 0.43 equivalent of H 2. To elucidate this slow dynamics, Density Functional Theory (DFT) optimized geometries followed by the natural bond orbital analysis revealed the formation of hydrogen bond between IL and amine borane moiety. Further, the presence of the stronger dihydrogen bond among the protic and hydridic hydrogens was also observed in AB + EDAB/[EMIM][SCN] system, resulting in longer induction period for dehydrogenation.
Journal of the Taiwan Institute of Chemical Engineers, 2019
The present study addressed the degradation kinetics of cholesterol lowering statin drug using me... more The present study addressed the degradation kinetics of cholesterol lowering statin drug using metal-free polymeric catalyst g-C 3 N 4 synthesized through sonochemical method followed by thermal condensation. The photocatalytic experiments were performed to assess the catalytic activity of the synthesized g-C 3 N 4 catalyst. The results revealed that the g-C 3 N 4 possesses high oxidation properties and able to degrade ∼93% of lovastatin within a short span of time 10 min under sono-hybrid technique with a rate constant of 15.1 × 10-2 min-1. On the other hand, the maximum synergy index was attained when the ultrasound was applied with g-C 3 N 4 nanoparticles. A significant enhancement of 2.25 folds higher degradation efficiency was achieved as compared to the sonolysis process alone. This enhancement is due to the addition of catalyst which facilitates more nucleation sites for cavitation bubbles and promoted cavitation phenomenon in the system. The study of adsorption and oxidation processes revealed that the degradation of lovastatin was primarily by oxidation reaction. When the experiments were performed at low pH, a significant degradation was observed-which is due to the formation of hydronium ions (H 3 O +). This H 3 O + produces alternative and reactive species such as • OH, • O, HO • 2 in the presence of free electrons in the reaction solution. The maximum synergy was seen for (US + g-C 3 N 4) process followed by (US + g-C 3 N 4 + H 2 O 2 + UVC) and (US + UVC). The experimental results of stability and reusability of the catalyst also confirmed that the catalyst could be easily regenerated and reused for several times without losing any catalytic activity-which might be useful for reducing the total operating cost for a wastewater treatment plant.
The current work presents a mechanistic insight of hydrogen production from ammonia borane (AB) ... more The current work presents a mechanistic insight of hydrogen production from ammonia borane (AB) facilitated by the phosphonium based ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis (2,4,4-trimethylpentyl) phosphinate ([TDTHP][Phosph]). Prior to experiments, the IL was screened from a pool of 11 phosphonium ILs with the infinite dilution activity coefficients (IDAC) values as predicted by conductor like screening model segment activity coefficient (COSMO-SAC) theory. Thereafter, a dehydrogenation experiment of AB/[TDTHP][Phosph] was carried out at 105 o C and 4×10 2 mbar of gauge pressure, which yielded 2.07 equivalent hydrogen production. At higher temperature, the 11 B NMR characterization shows the suppression of induction period at 105 o C and appearance of borohydride anion after 1 min of dehydrogenation. Further, time-resolved characterization of AB/[TDTHP][Phosph] at 105 o C confirmed the appearance of polymeric aminoborane after 10 min with a subsequent formation of polyborazylene. HR-MS characterization coupled with 1 H resonance spectrum confirmed structural integrity of IL. The dual characterization of NMR and HR-MS led us to propose a dehydrogenation mechanism of AB/[TDTHP][Phosph] system.
The current work reports ionic liquid (IL) facilitated dehydrogenation of tert-butylamine borane ... more The current work reports ionic liquid (IL) facilitated dehydrogenation of tert-butylamine borane (TBAB) at 90 and 105°C. For the screening of potential IL solvent, solubility predictions of TBAB in ILs were performed by the conductor-like screening model segment activity coefficient (COSMO-SAC) model. The COSMO-SAC model predicted a logarithmic infinite dilution activity coefficient of −6.66 and −7.31 for TBAB in 1-butyl-3-methylimidazolium acetate [BMIM][OAc] and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate [TDTHP][Phosph], respectively. Hydrogen (1.95 equiv) was seen to release from TBAB/[BMIM][OAc] at 105°C, whereas TBAB/[TDTHP][Phosph] produced 1.63 equiv of hydrogen after 360 min of dehydrogenation. The proton nuclear magnetic resonance (1 H NMR) characterization of TBAB/IL systems revealed the structural integrity of ILs during dehydrogenation. Further characterization through the boron NMR (11 B NMR) technique disclosed the time-resolved formation and stability of the starting compound, intermediate boron moieties, and product distribution. The 11 B NMR characterization also revealed the fact that the TBAB/[TDTHP][Phosph] mixture dehydrogenates via bimolecular addition of TBAB by forming borohydride anion (−BH 4 −). It was seen to oligomerize with the subsequent addition of TBAB in the oligomer chain. For the TBAB/[BMIM][OAc] system, the 11 B NMR characterization could not identify the borohydride anion but confirmed a faster formation of the BN moiety when compared to the TBAB/[TDTHP][Phosph] system. On the basis of the NMR characterization, IL-facilitated dehydrogenation mechanism of TBAB is proposed.
The growing of food waste generation is gradually becoming a global problem due to the improper m... more The growing of food waste generation is gradually becoming a global problem due to the improper management of it. According to the Food and Agriculture Organization (FAO), United Nation, more than 1.3 million tonnes of food is being wasted. Food waste and food processing waste are abundant-which are rich in organic acids and nutrients. These acids and nutrients can be utilized for attractive and efficient generation of renewable and sustainable fuels such as biohydrogen through fermentation process. Many investigations have revealed a significant biohydrogen generation using food wastes from restaurant, dining hall and food processing industries. During the hydrogen generation through fermentation, several parameters influence the yield of hydrogen. Some of them are method of pre-treatment, feed composition, fermentation temperature, culture and substrate, solution pH, etc. Also, the presence of inert intermediates produced during the reaction in fermentation process reduces the process efficiency. Few studies have shown that the use of nanoparticles in fermentation process along with the application of short & cyclic ultrasound is beneficial to increase the process efficiency. The augmentation in ultrasound-assisted process is due to the physical and chemical effects of ultrasound in the medium through the phenomenon of cavitation. During the transient collapse of cavitation bubbles, several reactive species are produced which further participate in the thermochemical and biochemical reactions. Thus, enhances the rate of reaction by annihilation the complex sugars in food wastes. Additionally, the cavitational effect helps to reduce the growth of hydrogen inhibiting microorganism in the feed. This review demonstrates the potentiality of food waste for production of biohydrogen through fermentation process including a brief overview of process parameters that affect the fermentation process. Additionally, an overview of integrated fermentative process coupled with nanoparticles and ultrasound is also discussed for enhanced biohydrogen generation from food waste.
The present study reports the synthesis of metal-free polymeric catalyst, graphitic carbon nitrid... more The present study reports the synthesis of metal-free polymeric catalyst, graphitic carbon nitride (g-C 3 N 4), through sonochemical method followed by thermal treatment. The synthesized g-C 3 N 4 was characterized using XRD, DRS, FESEM, TGA, EDX, etc. and the characterization results revealed that it possesses medium band-gap energy, high thermal and chemical stability. The photo-activity of the catalyst was also evaluated using degradation of 5-Fluorouracil under different experimental conditions. The results revealed that the addition of H 2 O 2 during sonolysis process did not show any significant synergy. This is attributed to the low vapor pressure of H 2 O 2 that does not allow it to diffuse into the cavitation bubble to produce % OH radicals through sonolysis process. Using sono-hybrid process, more than 90% degradation was seen within 5 min of treatment with a rate constant of 3.95 × 10 −2 s −1. In alkaline medium, 5-Fluorouracil degradation occurred through defluorination and subsequently substitution of-OH group to the aromatic ring leading to formation of intermediates such as 2fluoro-3-oxopropanoic acid and urea. While sono-hybrid advanced oxidation processes (AOPs) helped towards complete mineralization through formation of smaller molecular compounds such as maleic acids, lactic acids, propanol, etc. On the other hand, the maximum synergy effect of ∼2.4 was seen for sonocatalysis process followed by hybrid-AOPs of (US + g-C 3 N 4 + H 2 O 2 + UVC) with a synergy factor of ∼2.2. Also, the synthesized catalyst exhibited the same catalytic activity even after 5 runs of sono-photocatalysis process for degradation of 5-Fluorouracil.
Journal of Industrial and Engineering Chemistry, 2018
Highlights COSMO-SAC screening on hydrogen sulfate based ionic liquids for EDAB dehydrogenation... more Highlights COSMO-SAC screening on hydrogen sulfate based ionic liquids for EDAB dehydrogenation Thermal dehydrogenation of EDAB with 1-ethyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquids 1 H and 11 B NMR characterization Natural bond orbital and total interaction energy calculation of EDAB/ionic liquid systems
Abstract The present study investigated sonochemical synthesis of Zr-ferrite nanoparticles under ... more Abstract The present study investigated sonochemical synthesis of Zr-ferrite nanoparticles under different operating parameters. In order to explore the sintering effect on ferrite phase formation, the synthesized ferrite particles were also calcined in the range of 200–900 °C. The obtained nanoparticles were characterized using XRD, FESEM, TEM, EDX, DRS, and VSM. The results revealed that the formation of ferrite phase needs external calcinations and in-situ microcalcination induced by transient cavitation is not sufficient for formation of spinel ferrite phases. The DRS results showed that it has a high capability of visible light absorption due to low band-gap energy in the range of 1.85 eV–1.93 eV. The change in band-gap energy is attributed to the crystalline size of the particle and the change of nature of the ferrite from amorphous to crystalline structure. While analysis of magnetic properties revealed that coercivity is dependent on calcination temperature and the solution pH. The highest coercivity and magnetic saturation were determined as 725 Oe and 0.750 emu/g; respectively. At higher pH, ferromagnetic behaviour with decreasing order in both magnetic saturation (Ms) and magnetic remanence (Mr) has been observed. To the best of our knowledge, this is the first report on magnetic properties of Zr-ferrite.
analysis of ultrasound-assisted biodiesel synthesis with Cu 2 O Catalyst and mixed oil feedstock ... more analysis of ultrasound-assisted biodiesel synthesis with Cu 2 O Catalyst and mixed oil feedstock using continuous (packed bed) and batch (slurry) reactors, Chemical Engineering Science (2017),
Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to ... more Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to OH radical based advanced oxidation processes due to distinct merits such as greater stability and non-selective persistent reactivity of SO4(-) oxidant species. The present study has attempted to highlight mechanistic features of persulfate-based decolorization of textile dye (Azorubine) using sono-hybrid techniques of activation. Three activation techniques, viz. sonolysis, Fe(2+) ions and UVC light and combinations thereof, have been examined. UVC is revealed to be the most efficient decolorization technique. The mechanism of sonolysis (i.e. thermal activation of persulfate in the bubble-bulk interfacial region) is revealed to be almost independent of the mechanism of UVC. Fe(2+) activation is revealed to have an adverse interaction with UVC due to scavenging of sulfate radicals by Fe(2+) ions. The best hybrid activation technique for persulfate-based degradation and mineralization of Azorubine is UVC+ultrasound. Due to independent mechanisms, degradation and mineralization of the dye obtained with simultaneous application of UVC and ultrasound is nearly equal to the sum of degradation and mineralization obtained using individual techniques.
Industrialization and urbanization affect the environment directly, and water is one of the prima... more Industrialization and urbanization affect the environment directly, and water is one of the primary natural resources which are affected significantly. With rapid development of science of nanotechnology, the use of nanomaterials in environmental applications, especially water treatment, has attracted the scientific community in the last decades. Nanomaterials have unique properties, for example, surface-to-volume ratio, quantum effect, low band-gap energy, etc., which give extra features in catalytic performance.
Nanotechnology-Based Industrial Applications of Ionic Liquids, 2020
Nanoparticles (NPs) have been applied in the field of nanotechnology and are an attraction in con... more Nanoparticles (NPs) have been applied in the field of nanotechnology and are an attraction in consideration of the scientific community because of their potential and wide applications in various areas such as electronic devices, biomedical science, and catalysis. The synthesis of NPs usually in the range of 1–100 nm through the green route using different biological or green technique entities has been actively followed as an alternative approach for the self-assemble atoms to form nuclei of nanoparticles. However, the processes for the synthesis of nanoparticles are influenced by several parameters like solution pH, morphological structure of reactants, reaction time, and temperature. Also, the size, shape, and geometry are the significant characteristics of NPs. Nanostructured materials can also be synthesized through different physical and chemical processes. However, biological synthesis is more favorable due to environment-friendly and green chemistry-based technique. This chapter addresses a brief overview of the recent techniques in the development and synthesis of nanoparticles via the biological method and their forthcoming applications for sustainable environmental application. The effects of the different parameters, as mentioned above, have also been discussed in detail with NP formation mechanisms using plant extracts associated with the geometry or morphology, spectral response and specific particle sizes, and explicit functionality for antimicrobial activity. The effect of NPs on antimicrobial activity is based on the inhibition properties of gram-positive and gram-negative bacteria.
Handbook of Nanomaterials for Wastewater Treatment, 2021
Abstract Water is an essential component for all living bodies starting from agriculture, industr... more Abstract Water is an essential component for all living bodies starting from agriculture, industry, to domestic cares. Only 1% of water is easily accessible of 2.5% freshwater in the world, although the world has 70% of water. Hence it is necessary to recycle the water to meet the necessity of the world. Moreover, many process industries are also discharging wastewater directly to the environment without any proper treatment, and this wastewater contains enormous complex refractory molecules that are not easy to degrade through conventional biological methods. Therefore advanced techniques for wastewater treatment are very much necessary to fulfill the ever-increasing requirements of the increasing population. Nanomaterial-based treatment techniques are found to be economical because of the reusability of the catalyst. Recently, the magnetic nanoparticles for wastewater treatment have changed the interest of the scientific community because the nanomaterials possess excellent properties—the synthesis process is simple, high stability, high adsorption capacity, can be regenerated easily, and recycled for several times without losing its properties. Among these various magnetic materials, the ferrite nanoparticles, which are nothing but the transitional metal oxides with spinel structures, have gained the topmost position in terms of wide applications because they have very simple chemical composition, excellent magnetic properties, and immense applications for wastewater treatment, catalyst, and electronic devices for biomedical applications. This chapter presents a critical account of the literature on synthesis of magnetic nanomaterial and its applications for effective degradation of bio-recalcitrant organic compounds appearing in discharges of chemical and process industries.
Graphical abstract Reaction Mechanism and Formation of Fine Emulsion due to Physical Effects of C... more Graphical abstract Reaction Mechanism and Formation of Fine Emulsion due to Physical Effects of Cavitation in Liquid-Liquid Heterogeneous System.
The emerging contaminants in wastewater discharged from numerous chemical process industries, pha... more The emerging contaminants in wastewater discharged from numerous chemical process industries, pharmaceutical industries, textile, and wineries have attracted the attention of the scientific community due to their toxicity and persistence in the environment. The conventional techniques are incompetent to treat many of such recalcitrant toxic pollutants. To achieve high mineralization, advanced oxidation processes (AOPs) are found to be more efficient for the degradation of these organic pollutants without producing secondary pollutants with no/less amount of sludge. The primary oxidation agents for AOPs are in-situ generated free radicals, which are highly reactive and effective oxidants for degrading any type of organic molecules present in the wastewater. In the past decades, the combination of AOPs or simultaneous application of more than one AOP has been investigated extensively for wastewater treatment and these hybrid-AOPs have been reported to be beneficial for high-level mineralization of organic pollutants. This paper presented the characteristics, properties and influence of parameters in sono-photo-ferrioxalate system. The primary operating parameters in sono-photo-ferrioxalate system that affect the kinetics are defined as the solution pH, temperature, molar ratio of Fe3+/C2O42-, H2O2 concentration, source of light, ultrasound intensity, dissolved gases, and size of cavitation bubble. In this process, several oxidizing radicals are generated such as HO•, HO2•, C2O4•-, CO2•- and O2•- which are also responsible for degradation. In this review, we have mainly addressed the degradation of recalcitrant pollutants using the sono-photo-ferrioxalate system and a critical analysis of process parameters that influence mineralization efficiency.
In this study, the aim was to explore the effectiveness of the UV/H2O2 photolysis (UVP) process i... more In this study, the aim was to explore the effectiveness of the UV/H2O2 photolysis (UVP) process in terms of antimicrobial activity reduction and increasing the mean oxidation number of carbon (MONC) under the degradation of chloramphenicol (CHPL) drug. CHPL degradation kinetics and the effects of foreign anions on CHPL degradation were explored in this study. The order of the inhibition effect was found as Cl− > NO3− > HCO3− due to their different in HO• radical scavenging capacity. A pseudo-first-order model for CHPL degradation was well established, and the rate constant (kobs) was 2.93 × 10−2 min−1 (R2 = 0.98) in UVP. Thirteen intermediate products were detected in MS-chromatogram and were identified through different proposed degradation pathways. The cleavage of the amide side chain in CHPL was more effective in CHPL degradation due to an electrophilic attacks by HO. radicals on it. The inactivation rates of E. coli were decreased due to the reduction of -NO2 group into -...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of the Taiwan Institute of Chemical Engineers, 2019
Abstract In this study, an attempt was made to investigate the mechanistic insight to identify th... more Abstract In this study, an attempt was made to investigate the mechanistic insight to identify the links between enzymatic and sonolysis processes through degradation mechanism. Experimental results revealed that ultrasound and cavitation increase the number of collision in enzymatic process through intense convection in the medium generated by transient cavitation, and enhances degradation efficiency by increasing interaction between enzyme and organic molecules. The formation of pH· radicals in Bisphenol-A degradation is significant and it needs external binding agent such as polyethylene glycol (PEG) to prevent the blocking of reactive sites of enzymes. On the other hand, Ciprofloxacin is susceptible to enzyme, and thus the degradation enhancement is not much significant in sono-enzymatic process. The highest degradation rates at optimum condition of pH 7.0 and 25 °C were 66.52% and 68.41% for Bisphenol-A and Ciprofloxacin, respectively. The antimicrobial activity test and the LCMS results revealed that the intermediates (acetic acid, ethyl alcohol and other products with –OH group) formed during sono-enzymatic reaction are less toxic as compared to that formed in enzymatic process. This essentially means that the enzymatic process initiates the degradation reaction and ultrasound helps towards complete mineralization by degrading the intermediates. To the best of our knowledge, this is the first report on detailed degradation mechanism of Bisphenol-A and Ciprofloxacin using enzymatic and sono-enzymatic processes.
Asia-Pacific Journal of Chemical Engineering, 2019
The present investigation reports the effect of thiocyanate-based ionic liquid (IL) on the therma... more The present investigation reports the effect of thiocyanate-based ionic liquid (IL) on the thermal dehydrogenation of amine boranes. Fifteen ILs based on thiocyanate anion comprising cations from imidazolium, pyrrolidinium, and ammonium family were screened by a priori prediction of infinite dilution activity coefficient using the quantum chemical-based conductor-like screening model segment activity coefficient method. The IL with the highest predicted solubility of amine boranes converged to 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) that was then used for the dehydrogenation reaction. In the IL medium, ammonia borane (AB) and ethylene diamine bisborane (EDAB) were found to produce~1.64 equivalent of hydrogen with an induction period of 60 min and~2.37 equivalent of hydrogen having an induction period of 30 min, respectively. It was observed that the mixture of AB and EDAB in [EMIM][SCN] produced prolonged induction period of 210 min. After 240 min, the mixed amine boranes only produce 0.43 equivalent of H 2. To elucidate this slow dynamics, Density Functional Theory (DFT) optimized geometries followed by the natural bond orbital analysis revealed the formation of hydrogen bond between IL and amine borane moiety. Further, the presence of the stronger dihydrogen bond among the protic and hydridic hydrogens was also observed in AB + EDAB/[EMIM][SCN] system, resulting in longer induction period for dehydrogenation.
Journal of the Taiwan Institute of Chemical Engineers, 2019
The present study addressed the degradation kinetics of cholesterol lowering statin drug using me... more The present study addressed the degradation kinetics of cholesterol lowering statin drug using metal-free polymeric catalyst g-C 3 N 4 synthesized through sonochemical method followed by thermal condensation. The photocatalytic experiments were performed to assess the catalytic activity of the synthesized g-C 3 N 4 catalyst. The results revealed that the g-C 3 N 4 possesses high oxidation properties and able to degrade ∼93% of lovastatin within a short span of time 10 min under sono-hybrid technique with a rate constant of 15.1 × 10-2 min-1. On the other hand, the maximum synergy index was attained when the ultrasound was applied with g-C 3 N 4 nanoparticles. A significant enhancement of 2.25 folds higher degradation efficiency was achieved as compared to the sonolysis process alone. This enhancement is due to the addition of catalyst which facilitates more nucleation sites for cavitation bubbles and promoted cavitation phenomenon in the system. The study of adsorption and oxidation processes revealed that the degradation of lovastatin was primarily by oxidation reaction. When the experiments were performed at low pH, a significant degradation was observed-which is due to the formation of hydronium ions (H 3 O +). This H 3 O + produces alternative and reactive species such as • OH, • O, HO • 2 in the presence of free electrons in the reaction solution. The maximum synergy was seen for (US + g-C 3 N 4) process followed by (US + g-C 3 N 4 + H 2 O 2 + UVC) and (US + UVC). The experimental results of stability and reusability of the catalyst also confirmed that the catalyst could be easily regenerated and reused for several times without losing any catalytic activity-which might be useful for reducing the total operating cost for a wastewater treatment plant.
The current work presents a mechanistic insight of hydrogen production from ammonia borane (AB) ... more The current work presents a mechanistic insight of hydrogen production from ammonia borane (AB) facilitated by the phosphonium based ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis (2,4,4-trimethylpentyl) phosphinate ([TDTHP][Phosph]). Prior to experiments, the IL was screened from a pool of 11 phosphonium ILs with the infinite dilution activity coefficients (IDAC) values as predicted by conductor like screening model segment activity coefficient (COSMO-SAC) theory. Thereafter, a dehydrogenation experiment of AB/[TDTHP][Phosph] was carried out at 105 o C and 4×10 2 mbar of gauge pressure, which yielded 2.07 equivalent hydrogen production. At higher temperature, the 11 B NMR characterization shows the suppression of induction period at 105 o C and appearance of borohydride anion after 1 min of dehydrogenation. Further, time-resolved characterization of AB/[TDTHP][Phosph] at 105 o C confirmed the appearance of polymeric aminoborane after 10 min with a subsequent formation of polyborazylene. HR-MS characterization coupled with 1 H resonance spectrum confirmed structural integrity of IL. The dual characterization of NMR and HR-MS led us to propose a dehydrogenation mechanism of AB/[TDTHP][Phosph] system.
The current work reports ionic liquid (IL) facilitated dehydrogenation of tert-butylamine borane ... more The current work reports ionic liquid (IL) facilitated dehydrogenation of tert-butylamine borane (TBAB) at 90 and 105°C. For the screening of potential IL solvent, solubility predictions of TBAB in ILs were performed by the conductor-like screening model segment activity coefficient (COSMO-SAC) model. The COSMO-SAC model predicted a logarithmic infinite dilution activity coefficient of −6.66 and −7.31 for TBAB in 1-butyl-3-methylimidazolium acetate [BMIM][OAc] and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate [TDTHP][Phosph], respectively. Hydrogen (1.95 equiv) was seen to release from TBAB/[BMIM][OAc] at 105°C, whereas TBAB/[TDTHP][Phosph] produced 1.63 equiv of hydrogen after 360 min of dehydrogenation. The proton nuclear magnetic resonance (1 H NMR) characterization of TBAB/IL systems revealed the structural integrity of ILs during dehydrogenation. Further characterization through the boron NMR (11 B NMR) technique disclosed the time-resolved formation and stability of the starting compound, intermediate boron moieties, and product distribution. The 11 B NMR characterization also revealed the fact that the TBAB/[TDTHP][Phosph] mixture dehydrogenates via bimolecular addition of TBAB by forming borohydride anion (−BH 4 −). It was seen to oligomerize with the subsequent addition of TBAB in the oligomer chain. For the TBAB/[BMIM][OAc] system, the 11 B NMR characterization could not identify the borohydride anion but confirmed a faster formation of the BN moiety when compared to the TBAB/[TDTHP][Phosph] system. On the basis of the NMR characterization, IL-facilitated dehydrogenation mechanism of TBAB is proposed.
The growing of food waste generation is gradually becoming a global problem due to the improper m... more The growing of food waste generation is gradually becoming a global problem due to the improper management of it. According to the Food and Agriculture Organization (FAO), United Nation, more than 1.3 million tonnes of food is being wasted. Food waste and food processing waste are abundant-which are rich in organic acids and nutrients. These acids and nutrients can be utilized for attractive and efficient generation of renewable and sustainable fuels such as biohydrogen through fermentation process. Many investigations have revealed a significant biohydrogen generation using food wastes from restaurant, dining hall and food processing industries. During the hydrogen generation through fermentation, several parameters influence the yield of hydrogen. Some of them are method of pre-treatment, feed composition, fermentation temperature, culture and substrate, solution pH, etc. Also, the presence of inert intermediates produced during the reaction in fermentation process reduces the process efficiency. Few studies have shown that the use of nanoparticles in fermentation process along with the application of short & cyclic ultrasound is beneficial to increase the process efficiency. The augmentation in ultrasound-assisted process is due to the physical and chemical effects of ultrasound in the medium through the phenomenon of cavitation. During the transient collapse of cavitation bubbles, several reactive species are produced which further participate in the thermochemical and biochemical reactions. Thus, enhances the rate of reaction by annihilation the complex sugars in food wastes. Additionally, the cavitational effect helps to reduce the growth of hydrogen inhibiting microorganism in the feed. This review demonstrates the potentiality of food waste for production of biohydrogen through fermentation process including a brief overview of process parameters that affect the fermentation process. Additionally, an overview of integrated fermentative process coupled with nanoparticles and ultrasound is also discussed for enhanced biohydrogen generation from food waste.
The present study reports the synthesis of metal-free polymeric catalyst, graphitic carbon nitrid... more The present study reports the synthesis of metal-free polymeric catalyst, graphitic carbon nitride (g-C 3 N 4), through sonochemical method followed by thermal treatment. The synthesized g-C 3 N 4 was characterized using XRD, DRS, FESEM, TGA, EDX, etc. and the characterization results revealed that it possesses medium band-gap energy, high thermal and chemical stability. The photo-activity of the catalyst was also evaluated using degradation of 5-Fluorouracil under different experimental conditions. The results revealed that the addition of H 2 O 2 during sonolysis process did not show any significant synergy. This is attributed to the low vapor pressure of H 2 O 2 that does not allow it to diffuse into the cavitation bubble to produce % OH radicals through sonolysis process. Using sono-hybrid process, more than 90% degradation was seen within 5 min of treatment with a rate constant of 3.95 × 10 −2 s −1. In alkaline medium, 5-Fluorouracil degradation occurred through defluorination and subsequently substitution of-OH group to the aromatic ring leading to formation of intermediates such as 2fluoro-3-oxopropanoic acid and urea. While sono-hybrid advanced oxidation processes (AOPs) helped towards complete mineralization through formation of smaller molecular compounds such as maleic acids, lactic acids, propanol, etc. On the other hand, the maximum synergy effect of ∼2.4 was seen for sonocatalysis process followed by hybrid-AOPs of (US + g-C 3 N 4 + H 2 O 2 + UVC) with a synergy factor of ∼2.2. Also, the synthesized catalyst exhibited the same catalytic activity even after 5 runs of sono-photocatalysis process for degradation of 5-Fluorouracil.
Journal of Industrial and Engineering Chemistry, 2018
Highlights COSMO-SAC screening on hydrogen sulfate based ionic liquids for EDAB dehydrogenation... more Highlights COSMO-SAC screening on hydrogen sulfate based ionic liquids for EDAB dehydrogenation Thermal dehydrogenation of EDAB with 1-ethyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquids 1 H and 11 B NMR characterization Natural bond orbital and total interaction energy calculation of EDAB/ionic liquid systems
Abstract The present study investigated sonochemical synthesis of Zr-ferrite nanoparticles under ... more Abstract The present study investigated sonochemical synthesis of Zr-ferrite nanoparticles under different operating parameters. In order to explore the sintering effect on ferrite phase formation, the synthesized ferrite particles were also calcined in the range of 200–900 °C. The obtained nanoparticles were characterized using XRD, FESEM, TEM, EDX, DRS, and VSM. The results revealed that the formation of ferrite phase needs external calcinations and in-situ microcalcination induced by transient cavitation is not sufficient for formation of spinel ferrite phases. The DRS results showed that it has a high capability of visible light absorption due to low band-gap energy in the range of 1.85 eV–1.93 eV. The change in band-gap energy is attributed to the crystalline size of the particle and the change of nature of the ferrite from amorphous to crystalline structure. While analysis of magnetic properties revealed that coercivity is dependent on calcination temperature and the solution pH. The highest coercivity and magnetic saturation were determined as 725 Oe and 0.750 emu/g; respectively. At higher pH, ferromagnetic behaviour with decreasing order in both magnetic saturation (Ms) and magnetic remanence (Mr) has been observed. To the best of our knowledge, this is the first report on magnetic properties of Zr-ferrite.
analysis of ultrasound-assisted biodiesel synthesis with Cu 2 O Catalyst and mixed oil feedstock ... more analysis of ultrasound-assisted biodiesel synthesis with Cu 2 O Catalyst and mixed oil feedstock using continuous (packed bed) and batch (slurry) reactors, Chemical Engineering Science (2017),
Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to ... more Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to OH radical based advanced oxidation processes due to distinct merits such as greater stability and non-selective persistent reactivity of SO4(-) oxidant species. The present study has attempted to highlight mechanistic features of persulfate-based decolorization of textile dye (Azorubine) using sono-hybrid techniques of activation. Three activation techniques, viz. sonolysis, Fe(2+) ions and UVC light and combinations thereof, have been examined. UVC is revealed to be the most efficient decolorization technique. The mechanism of sonolysis (i.e. thermal activation of persulfate in the bubble-bulk interfacial region) is revealed to be almost independent of the mechanism of UVC. Fe(2+) activation is revealed to have an adverse interaction with UVC due to scavenging of sulfate radicals by Fe(2+) ions. The best hybrid activation technique for persulfate-based degradation and mineralization of Azorubine is UVC+ultrasound. Due to independent mechanisms, degradation and mineralization of the dye obtained with simultaneous application of UVC and ultrasound is nearly equal to the sum of degradation and mineralization obtained using individual techniques.
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Papers by Sankar Chakma