Study Of Removal Behavior And Mechanism On Cr(?) And Tetracycline In Water By Biomass-based Carbon Fibers

With the continuous intensification of social industrialization,environmental problems are becoming more and more serious,human life has been influenced a lot.Among them,Cr?VI?and tetracycline in water have been widely studied because of their serious pollution.In this paper,carbon fibers were successfully synthesized using marine biomass as raw material,and its removal behavior and mechanism of Cr?VI?and tetracycline were studied.Using solid waste Enteromorpha as raw material,this paper synthesized carbon fibers BC and two kinds of modified carbon fibers activated by KOH and H₃PO₄?WL-CHF?window-like structured carbon hollow fibers?and H3PO4-AC?,which were used to study its removal behavior and reaction mechanism with Cr?VI?.Results showed that WL-CHF has the largest adsorption capacity,fastest adsorption rate and best recyclability,because its unique tubular structure,large specific surface area and abundant adsorption sites are beneficial to the rapid capture for Cr?VI?.In addition,the adsorption process is fitted well with pseudo-second-order adsorption kinetic model and Langmuir isotherm model.The removal mechanism of WL-CHF with Cr?VI?includes reduction,ion exchange and electrostatic interaction of oxygen-containing functional groups.The outstanding performance of Enteromorph-based carbon fibers in the treatment of Cr-polluted water proved its prospect in environmental protection and economic market.Based on the good removal effect of carbon fibers on Cr?VI?,this paper continues to use another marine biomass carrageenan as raw material,FeCl3 as a coagulation bath to synthesize FeS/carbon fibers?FeS/CFs?by wet spinning and pyrolysis method.The sulfate groups enriched and double-helix structure in carrageenan-Fe could effectively avoid aggregation and loss of FeS nanoparticles in practical application.Results showed that FeS/CFs could effectively remove Cr?VI?from water and showed good reusability.The main removal mechanisms of FeS/carbon fibers on Cr?VI?reduction of Fe S,electrostatic interaction of carbon fibers and Cr?III?-Fe?III?complexation reaction.The adsorption models are fitted well with pseudo-second-order model and Langmuir model,illustrating the process is mainly controlled by chemical adsorption and belongs to monolayer adsorption on a uniform surface.Furthermore,co-existing anions,column and regeneration experiments proved the promising prospect of FeS/CFs in application.The above FeS/CFs were used as catalyst to activate persulfate?PMS?to degrade tetracycline in water.The effects of FeS/CFs dosage,PMS dosage,initial tetracycline concentration,pH and other experimental parameters on TC degradation were studied.Under the optimal conditions:FeS/CFs dosage=500 mg/L,PMS dosage=0.8 mM,initial TC concentration=500 mg/L,and the removal rate of TC could reach 65%in 1 minute under the ideal experimental conditions.The adsorption process of tetracycline by Fe S/CFs belongs to the Langmuir adsorption isotherm model,and the saturated adsorption capacity is 82.97 mg/g.The free radical quenching experiments illustrated that¹O₂ played a leading role in the degradation process,and its contribution was higher than SO4·-and·OH.Moreover,FeS/CFs displayed excellent stability and reusability,which demonstrated FeS/CFs were effective eco-friendly materials for TC treatment.To sum up,marine biomass Enteromorpha and carrageenan can be used to synthesize biomass-based carbon fibers for the treatment of Cr?VI?and TC in water.This study adheres to the concept of“treating waste with waste”,for realizing the reasonable and effective utilization of resources.