MgCl2 Modification-Preparation of Biochar from Distiller's Grains Rice Husk and Its Adsorption Performance to Ammonia Nitrogen in Fermented Liquid
The biochar was prepared with distiller's grain rice husk as raw material and MgCl2 as modifying reagent,and the best preparation conditions was at carbonization temperature of 700 ℃ and MgCl2 concentration of 0.20 mol/L.The prepared biochar was used to adsorb the ammonia nitrogen in the fermented liquid.When the biochar dosage was 10 g/L and the initial pH of the adsorption solution was 12,the maximum adsorption capacity and removal efficiency of 43.59 mg/g and 65.64％respectively were obtained.The characterization of biochar showed that impregnation with MgCl2 solution increased the specific surface area of biochar,improved its pore structure,and deposited a layer of magnesium-containing crystalline compounds on the surface of biochar.This changes of biochar after modification effectively improved the adsorption effect on ammonia nitrogen.Furthermore,the adsorption behavior was explored by fitting the experimental data with the model.The pseudo-second-order kinetic model was more consistent with the adsorption process of magnesium-modified biochar to ammonia nitrogen than that of the quasi-first-order kinetic model,indicating that the adsorption process was mainly chemical adsorption.In the isothermal mode,the R2 of the Langmuir model was slightly higher than that of the Freundlich model.The maximum theoretical adsorption capacity obtained by the Langmuir model was 106.99 mg/g.The two models showed that the adsorption process of ammonia nitrogen on the biochar was a kind of favorable adsorption.
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