Papers by Michael Hojjatie
A process for preparing a calcium thiosulfate solution comprising: providing a suspension of calc... more A process for preparing a calcium thiosulfate solution comprising: providing a suspension of calcium hydroxide; adding sulfur to the calcium hydroxide slurry and reacting sulfur with calcium hydroxide to form a reaction mixture; cooling the reaction mixture, if necessary, to a temperature suitable for oxidation; adding to the reaction mixture an oxidant and reacting under conditions sufficient to form calcium thiosulfate; and recovering the calcium thiosulfate solution.
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a batch method or effective semicontinuous production of calcium thiosulfate (CaS {sub, 2} O {sub... more a batch method or effective semicontinuous production of calcium thiosulfate (CaS {sub, 2} O {sub, 3}) containing low byproduct content, high relative concentration, from lime, sulfur or polysulfide is described calcium, and sulfur dioxide under conditions of elevated reaction temperature. The product is an emulsion of liquid calcium thiosulfate and solid byproducts. Under the conditions of the art, including the mole ratios of lime with respect to sulfur, the temperature of reaction procedure and reaction conditions of sulfur dioxide, including the rate and duration, the byproducts are reduced to about 2% in weigh.
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Adding the patent number P201131555, by a continuous process for preparing a liquid solution of c... more Adding the patent number P201131555, by a continuous process for preparing a liquid solution of calcium thiosulfate. # An efficient process for the continuous preparation of calcium thiosulfate (CaS {sub, 2} O {sub is described, 3) from calcium sulfide by oxidation. The process involves oxidizing an intermediate of calcium polysulfide in a series of reactors to produce calcium thiosulfate as a clear liquid at high concentration with minimal byproducts. The process produces the complete destruction of polythionates, allowing the calcium thiosulfate produced is useful in certain leaching processes for precious metals. The invention further makes it possible to recycle the process water from the leaching process for use as raw material reactive in the process for the production of calcium thiosulfate.
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The invention relates to a process for the efficient preparation of manganese semicontinuous thio... more The invention relates to a process for the efficient preparation of manganese semicontinuous thiosulfate (MnS2O3., DTMs) from hydrosulfite manganese and sulfur at high temperatures. The method comprises preparing manganese hydrosulfite from manganese carbonate and sulfur dioxide under certain conditions, that is to say, molar ratios, pH, time and temperature.
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CONCERNS FOR PREPARING AN ONGOING PROCESS thiosulfate CALCIUM FROM calcium sulfide by oxidation. ... more CONCERNS FOR PREPARING AN ONGOING PROCESS thiosulfate CALCIUM FROM calcium sulfide by oxidation. The process involves oxidizing a sulfide intermediate CALCIUM IN A SERIES TO PRODUCE THIOSULFATE REACTORS CALCIUM AS A HIGH CONCENTRATION TRANSPARENT LIQUID PRODUCTS WITH MINIMAL. The process produces the complete destruction of polythionates, allowing calcium thiosulfate produced is useful in certain processes Leaching PRECIOUS METALS
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a batch method or effective semicontinuous production of calcium thiosulfate (CaS {sub, 2} O {sub... more a batch method or effective semicontinuous production of calcium thiosulfate (CaS {sub, 2} O {sub, 3}) containing low byproduct content, high relative concentration, from lime, sulfur or polysulfide is described calcium, and sulfur dioxide under conditions of elevated reaction temperature. The product is an emulsion of liquid calcium thiosulfate and solid byproducts. Under the conditions of the art, including the mole ratios of lime with respect to sulfur, the temperature of reaction procedure and reaction conditions of sulfur dioxide, including the rate and duration, the byproducts are reduced to about 2% in weigh.
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International Journal of Agricultural Science and Food Technology, 2021
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Journal of Pharmacology & Pharmaceutical Research, 2019
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Journal of Chromatography B: Biomedical Sciences and Applications, 1986
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Journal of AOAC International, 2015
Currently there are three AOAC Official Methods for the determination of urea in fertilizers. AOA... more Currently there are three AOAC Official Methods for the determination of urea in fertilizers. AOAC Official Method 959.03, Urea in Fertilizers, Urease Method, First Action 1959, Final Action 1960, is based on the use of fresh commercial 1% urease solution, or preparation of such solution from urease powder in water, or from jack bean meal in water. AOAC Official Method 983.01, Urea and Methyleneureas (Water-Soluble) in Fertilizers, First Action 1983, Final Action 1984, is based on LC with a refractive index detector using water as the mobile phase and a C18 column. AOAC Official Method 2003.14, Determination of Urea in Water- Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions, First Action 2003, Final Action 2008, is based on LC with a UV detector using acetonitrile-water (85+15, v/v) mobile phase and a propylamine column. The urea method, AOAC Official Method 959.03, is very much dependent on the nature of the urease enzyme. The method was developed in 1960 and used for simple urea fertilizer solutions. With the advent of complex fertilizer compositions, especially with the class of liquid triazone fertilizers and water-soluble urea forms, the analyses of free urea in these fertilizers by the urease method is often inaccurate and inconsistent. AOAC Official Method 983.01 is not always reliable due to the interference of some of the components of these fertilizers, and due to the fact that the use of water as the mobile phase does not always separate the free urea from other components. AOAC Official Method 2003.14 was subjected to ring test studies that showed it could be used for the determination of "free urea" in these classes of fertilizers with good accuracy and precision.
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Journal of AOAC INTERNATIONAL, 2014
In AOAC Official MethodSM 955.04, Nitrogen (Total) in Fertilizers, Kjeldahl Method, fertilizer ma... more In AOAC Official MethodSM 955.04, Nitrogen (Total) in Fertilizers, Kjeldahl Method, fertilizer materials are analyzed using mercuric oxide or metallic mercury (HgO or Hg) as a catalyst. AOAC Official MethodSM 970.02, Nitrogen (Total) in Fertilizers is a comprehensive total nitrogen (including nitrate nitrogen) method adding chromium metal. AOAC Official MethodSM 978.02, Nitrogen (Total) in Fertilizers is a modified comprehensive nitrogen method used to measure total nitrogen in fertilizers with two types of catalysts. In this method, either copper sulfate or chromium metal is added to analyze for total Kjeldahl nitrogen. In this study, the part of AOAC Official MethodSM 978.02 that is for nitrate-free fertilizer products was modified. The objective was to examine the necessity of copper sulfate as a catalyst for the nitrate-free fertilizer products. Copper salts are not environmentally friendly and are considered pollutants. Products such as ammonium sulfate, diammonium phosphate, m...
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Journal of AOAC International, 2014
A single-laboratory validation (SLV) study for the LC determination of biuret in dry and liquid u... more A single-laboratory validation (SLV) study for the LC determination of biuret in dry and liquid urea-based commercial fertilizers was conducted. A total of 23 samples were used: 11 commercial dry urea products, two urea ammonium nitrate products, eight liquid urea-based commercial fertilizers, and four sulfur-coated urea samples from different sources. In addition, one biuret standard from Aldrich and one sample from the Magruder check sample program were used as validation samples. The proposed method is an extension of AOAC Official MethodSM 2003.14 and is based on dissolution of the test portion in the LC mobile phase and determination by HPLC. The system is linear over a concentration range of 1.00–4.50 mg/L biuret, with a correlation coefficient ≥0.9999. The biuret was well- separated from urea in the commercial urea samples, and from other constituents in the commercial liquid fertilizer with no observed interferences. Recoveries were determined by spiking four of the validati...
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Papers by Michael Hojjatie