Guar gum modification

This research work deals with the preparation of a series of hydrogels using renewable resources, in order to decrease the adverse impact on the environment, and understand their swelling behavior. Hydrogels were synthesized using guar gum and chitosan with glutaraldehyde as the cross-linking agent, protonated with 98% conc. sulphuric acid. Concentration of chitosan was varied as 0, 12.5, 25, 37.5 and 50% (w/w) in guar gum, while that of glutaraldehyde was varied as 0, 1.5, 3 and 6% (w/w) of the total quantity of guar gum and chitosan. Prepared hydrogels were characterized for moisture content, equilibrium water absorbency, re-swelling capacity, swelling ability in acidic (pH = 3) and basic (pH = 11) pH distilled water, equilibrium saline water absorbency and Fourier transform infrared spectroscopy. It was determined that moisture content, equilibrium water absorbency and equilibrium saline water absorbency decreased with increased concentration of chitosan and glutaraldehyde, but they still had water swelling to be classified as hydrogel. Re-swelling capacity of the hydrogels decreased with increased cycles of reswelling. Prepared hydrogels maintained high water swelling in acidic pH distilled water as compared to basic pH distilled water. This hydrogels can be utilized as eco-friendly water manageable materials.

Guar, a small bean grown in Indian subcontinent has become a prized international commodity, since the rise of Hydraulic Fracturing on international level. Guar gum plays a crucial role in the fracturing process. Its dispersibility in water and mineral oil assist in pushing fracturing fluid through solid rock to reach petrochemical deposits of earth's crust. Though India accounts for 80% production of the world's total guar cultivation, but still it couldn't take the advantage, as only 10% of the production is used in India and rest 90% gets exported to oil and gas industries in outside countries. The reason is the extensive use of Guar gum and its derivatives as fracturing fluids in other countries. Hydraulic fracturing allows the producers to safely recover oil and gas resources from deep reserves. The intent of this paper is to introduce this efficient Hydraulic fracturing technology in the extraction of shale gas and few oils too, considering the vast shale deposit as well as guar in India, opening the vast unassessed energy reserve.

We report a facile and green method to synthesise highly stable dispersions of platinum nanoparticles (PtNPs) with an average particle size of ∼6 nm. Natural, nontoxic, eco-friendly biopolymer guar gum was utilised as both the reducing and capping agent precursor in aqueous medium. The PtNPs that had been stabilised by guar gum (GG-s-PtNPs) were characterised by UV-vis spectroscopy, XRD, TEM and XPS. GGs-PtNPs performed better in terms of catalytic activity for the liquid phase reduction of p-nitrophenol (p-NP) compared to p-aminophenol (p-AP). The efficiency of the catalytic reduction of p-NP over GG-s-PtNPs was found to be 97% in a total time of 320 s at room temperature. The mechanisms of the synthesis and catalytic reduction of p-NP are also discussed. The synthesis approach presented here does not require stringent conditions or toxic agents and thus is a straightforward, rapid, efficient, and green approach to the fabrication of highly active catalysts.

Novel nanocomposite adsorbent materials were synthesized by condensation polymerization of TEOS in the presence of saponified guar-graft-poly(acrylonitrile) (SG) as template. The effect of changing the molecular size of SG on the final properties of the composite materials was investigated in this paper. The composites were thermally treated at temperatures ranging from 80 to 1100 °C, to obtain materials of different performance. The chemical, structural and textural characteristics of the composites were determined by FTIR, XRD, TGA-DSC and SEM studies. Their adsorption properties were monitored in terms of Zn (II) binding capacity which could be tailored by changing the template size and sintering temperature. The adsorption capacity of the composite at room temperature was enhanced five times when thermally treated at 900 °C with a maximum adsorption of 3.58 meq/g of the zinc (II). The adsorption could be further optimized to higher values and the materials could be successfully recycled for three consecutive cycles without any significant loss in the adsorption capacity.

Using persulfate/ascorbic acid redox pair, poly(methylacrylate) was grafted on to guar gum and the conditions for the grafting were optimized. The copolymer sample having maximum %G was evaluated for the removal of Cr(VI) and the sorption conditions were optimized. The sorption was found pH dependent, pH 1.0 being the optimum value. Sorption data at pH 1.0 were modeled using both the Langmuir and Freundlich isotherms where the data fitted better to Freundlich isotherm. The equilibrium sorption capacity of 29.67 mg/g was determined from the Langmuir isotherm. The sorption followed a pseudo-secondorder kinetics with a rate constant 2.5 Â 10 À4 g mg À1 min À1 . The grafted product was also evaluated for Cr(VI) removal from local electroplating industrial waste water. The regeneration experiments revealed that the guar-graft-poly(methylacrylate) could be successfully reused for five cycles. In the present study conductivity measurements were used instead of conventional photometric method for determining Cr(VI) concentration in the equilibrium solutions and the results obtained have been compared with photometric method. Optimum Cr(VI) binding under highly acidic conditions indicated significant contribution of non electrostatic forces in the adsorption process.