Absorbtion Characteristics Of Supported FeS Modified Soy Sauce Residue Biochar To Hexavalent Chromium In Aqueous Solution

In heavy metal pollution,Cr is one of the main elements causing environmental pollution problems.Biochar has been widely used in the treatment of heavy metal wastewater due to its low preparation cost and abundant pore size structure and good adsorption performance for heavy metal ions in water.Sauce residue is a potential material for the preparation of biochar because of its high content of carbon and cellulose.However,due to the high content of crude fat and protein,the yield of biochar prepared by pyrolysis is low and its adsorption property is poor.This study selects the ammonium dihydrogen phosphate and load FeS particles on the pretreatment and modification,preparation of modified biochar load FeS,preprocessing and modified way and through the research on its surface structure and the influence of Cr⁶⁺in water adsorption properties and adsorption mechanism of Cr⁶⁺then select the water removal performance of the modified sauce residue biochar,the preparation and modification for biochar offers a new approach,is to make this kind of agricultural biomass waste slag comprehensive utilization to provide a new way of thinking.Through this study,the following conclusions are drawn:?1?The yield of the sauce residue biochar pretreated with ammonium dihydrogen phosphate solution was increased by 51.86%,and the H/C and O/C were reduced by 27.27%and 29.41%,respectively,compared with that of the unpretreated sauce residue biochar,indicating that it had higher degree of carbonation and aromatization,and had higher stability in water.The results of ir and sem showed that the pretreated biochar had more-OH and-O=C and complex surface structure.?2?The biochar prepared by pretreatment with 1:20 solid-liquid specific ammonium dihydrogen phosphate solution has the best adsorption performance.The optimal adsorption pH was 4.0,the adsorption equilibrium time was 180 min,and the maximum unit amount of hexavalent chromium in the biochar of sauce residue was 31.655mg g^-1,respectively.Sauce residue biochar in a second dynamic adsorption mechanism,adsorption process conforms to the quasi R² is 0.995,shows that the adsorption process,mainly chemical adsorption,the more accord with the Freundlich isothermal adsorption model of adsorption process for heterogeneous multilayer adsorption,adsorption thermodynamics?H,?S>0,?G<0 indicated that the adsorption process is a spontaneous endothermic reaction.?3?The biochar prepared with 1:20 solid-liquid ratio as raw material was prepared by adding different proportions of FeS,chitosan and biochar.The results showed that FeS particles with a diameter of 400-500 nm were successfully attached to the surface by adding FeS and chitosan,and the surface structure of biochar was improved.?4?The adsorption of hexavalent chromium in water was best when the ratio of FeS,chitosan and biochar was 1:1:1.The optimal adsorption pH was 4.0,and the adsorption equilibrium time was 210 min.The maximum unit adsorption of hexavalent chromium on the supported sulfurated biocarbon was 96.41 mg g^-1.The adsorption process of modified biochar supported by FeS was more in line with the quasi-second order kinetic equation,indicating that the adsorption process was dominated by chemical adsorption.Langmuir model can better describe the adsorption process,indicating that the adsorption process is monolayer adsorption on a uniform surface,and the adsorption strength index 1/n is between 0.1 and 0.5,indicating that the adsorption is easy to be carried out.Thermodynamics,according to the results of fitting in the adsorption of?G and?H<0,showed the FeS biological carbon materials to hexavalent chromium adsorption is a spontaneous endothermic reaction.