Study On Colloidal Activated Carbon Rapid Interception Coupling Bioremediation Of Nitrobenzene Contaminated Groundwater

Colloidal activated carbon（ACC）is a multifunctional adsorbent and carrier nanomaterial for in-situ remediation of groundwater.Activated carbon colloids（ACC）can be injected into the groundwater as water suspensions,which can establish adsorption reaction barriers in groundwater and provide active areas for microbial degradation of nitrobenzene,receiving special attention.Nitrobenzene,as a common organic toxic pollutant in the modern chemical industry,has been increasing in demand and emissions due to its application.Therefore,using colloidal activated carbon to solve the problem of nitrobenzene pollution in groundwater is the main research direction of this article.In this study,colloidal activated carbon was prepared by ball milling method,and modified with four modifiers（sodium carboxymethyl cellulose,humic acid,xanthan gum,and sodium dodecylbenzene sulfonate）.Its morphology,structure,and elemental composition were characterized.The dispersion stability and migration effect of the four modified active carbon suspensions were investigated.The adsorption kinetics and adsorption ability of CMC and HA modified colloidal activated carbon for NB were discussed,The factors affecting the degradation of adsorbed nitrobenzene by coupled microorganisms were investigated.The results show that the particle size of activated carbon after ball milling can reach 10μm or even smaller range,the surface is smoother after modification,the pore structure is increased,and the active site available are increased;Through characterization of Zeta potential and sedimentation experiments,it was found that unmodified activated carbon began to settle in a short period of time,while the addition of modifiers did not significantly cause solution stratification for a period of timeζThe data from potential and absorbance analysis confirm this conclusion;The colloidal activated carbon modified with four modifiers has better stability effect in the suspension after CMC modification.When the p H is 8.0 and the concentration is1.5 g/L,the dispersion stability is better.Through the migration experiment of modified colloidal activated carbon,it was found that the migration rates of CMC and HA colloidal activated carbon in porous media were higher than those of SDBS and XG.The migration rates of H-ACC and C-ACC could reach 85%and 82%respectively.It was found through adsorption experiments that the adsorption capacity of C-ACC for NB was 51.25 mg·g^-1,which was higher than that of H-ACC(42.35 mg·g^-1)and PAC(18.56 mg·g^-1).Through kinetic model fitting results,The adsorption of NB by C-ACC on colloidal activated carbon conforms to the pseudo-second-order kinetic model（R²=0.9997）.The fitting results of adsorption isotherm data showed that the adsorption isotherm of C-ACC for NB was consistent with the fitting figure of Langmuir model Type II（R²=0.9998）.Moreover,Langmuir’s isothermal adsorption model of C-ACC also indicates that the adsorption of NB on C-ACC should be the single-layer covering adsorption of NB on the outer surface of colloidal activated carbon,and the adsorption capacity is limited and in a dynamic equilibrium process.The results of adsorption of NB by C-ACC under different reaction conditions show that when p H is 8.0,temperature is 25℃and concentration of C-ACC is 1.5 g/L,the adsorption effect of nitrobenzene（concentration is 100 mg/L）is the best,In addition,in the presence of ions,the adsorption of NB by C-ACC will be inhibited,in which Ca²⁺>Na⁺>K⁺.Explored the effect of microorganisms NB-1 on the degradation of adsorbed nitrobenzene,and selected n-hexane and acetone extraction methods to achieve better recovery of nitrobenzene by spiking.Further results on the environmental factors affecting the degradation of adsorbed nitrobenzene by microorganisms showed that when the dosage of microorganisms was 5 m L,the initial p H value was 8.0,the temperature was 25℃,and the degradation time was 16 hours,the removal efficiency of adsorbed nitrobenzene by microorganisms was the highest,with a degradation rate of 87%.When the concentration of nitrobenzene was too high,it would have an inhibitory effect on the degradation of microorganisms.The research results provide a theoretical basis for the remediation of nitrobenzene contaminated groundwater through the preparation of colloidal activated carbon,the optimization of surface modification methods,the dispersion,stability,and migration of suspension solutions,and the adsorption and interception of NB coupled with microbial degradation.