Research On The Adsorption Mechanism Of Arsenic(?) In Wastewater By Modified Biochar

Biochar is a kind of stable porous carbonaceous solid formed by pyrolysis or carbonization of various biomasses in anoxic or anaerobic environment,which itself has a certain adsorption effect on heavy metals and organic matter in soil or water.In this experiment,the chestnut shell biomass was modified with magnetic gelatin to increase its adsorption performance after calcining it into biochar.An environmentally friendly and inexpensive organic composite adsorbent material has been formed and the arsenic?V?in wastewater could be efficiently removed.The adsorption rate of modified sorbent magnetic gelatin biochar?MG-CSB?to As???(45.8mg g^-1)was much higher than that(17.85 mg g^-1)of original chestnut shell biochar?CSB?.In this experiment,scanning electron microscopy?SE M?,Fourier transform infrared spectroscopy?FT-IR?and X-ray photoelectron spectroscopy?XPS?were used to characterize the derivative materials.The results showed that the amino and carboxyl functional groups on the surface of the material promoted the adsorption.Simultaneous experiments with a series of adsorption effects also demonstrated that the adsorption of As???on magnetic gelatin modified biochar also includes surface electrostatic interactions.Therefore,the potential adsorption mechanism of MG-CSB on pentavalent arsenic includes surface electrostatic interaction and the complexation between the functional groups on the surface of the material during the adsorption process,mainly due to the effect of As-O.In this study,a series of experiments were conducted to investigate the removal performance of pentavalent arsenic in water from this novel material.The experimental results show that the kinetic model of magnetic gelatin biochar can meet the pseudo-second-order kinetic model for As???,and the isotherm conforms to the Langmuir model.When the pH is 4.0,the adsorption of As???by modified biochar has the largest adsorption capacity.It can reach 45.8mg g^-1.Thermodynamic data show that the reaction is a spontaneous and endothermic reaction process,and the increase in temperature favors the reaction.This experiment explored the effect of background electrolytes on the removal performance.The results show that under the presence of negative ions,the adsorption of pentavalent arsenic by MG-CSB does not change significantly,but decreases slightly,whereas in the presence of negative ions,the adsorption of valence arsenic has decreased significantly.This experiment also explored the effect of ion concentration on the adsorption properties of the material,but as the ion concentration increases,the material adsorption performance is significantly improved.In summary,the environmentally friendly magnetic gelatin modified chestnut shell biochar has a strong adsorption effect on pentavalent arsenic in wastewater,and can be used as an adsorbent with excellent physical and chemical properties.