Study On The Remove Of Chlorinated Phenol In Wastewater By Fe Series @Biochar

Chlorophenols are important organic chemical raw materials and intermediates,which are widely used.Because of their biological toxicity,long-term residue,bioaccumulation and other characteristics,chlorophenols have been listed as priority pollutants for environmental monitoring in many areas.How to deal with them effectively has become the focus of attention.Nano zero valent iron（NZVI）has become a research hotspot in the field of water pollution treatment because of its large specific surface area and strong reactivity.However,NZVI in the application process has the following shortcomings,such as the particle size is very small,its own magnetism is easy to agglomerate,after the reaction will form a passivation layer wrapped in its own surface,resulting in the reduction of reaction activity.Biochar,with its well-developed pore structure,many binding sites and strong adsorption capacity,has been widely used in the field of water pollution treatment.In this study,2,4-dichlorophenol（2,4-DCP）was used as the target pollutant,and biochar from soybean straw was used as the carrier of zero valent iron to prepare Fe@biochar,so as to improve the removal ability and reaction stability of zero valent iron for chlorophenols.Sodium thiosulfate was used as sulfur source to modify the material and enhance the treatment performance of the material for the target pollutants.The preparation process and reaction conditions of biochar were optimized by designing the control experiment of pollutant removal performance Fe@Biochar The removal performance of chlorophenols and the removal mechanism were briefly speculated.The main conclusions are as follows:（1）The preparation process of Fe@biochar and the effect of treatment conditions on the removal performance of 2,4-DCP were studied.Different contents of Fe and biomass were loaded by ultrasonic impregnation,and then pyrolyzed and carbonized slowly in gradient Fe@Biochar Material Science.The control experiment results show that the longer the pyrolysis time,the higher the removal efficiency of target pollutants.When the content of Fe³⁺is 1 mmol/g,Fe@Biochar The removal rate of target pollutants is close to 100%.When the material dosage is 1.0 g/L,the removal rate of 2,4-DCP can reach more than 90%within 4 h.When the initial solution pH was 3.0,the removal rate of 2,4-DCP by Fe@biochar reached 87%within 4 h.（2）The removal performance and mechanism of 2,4-DCP by sulfurized Fe@biochar were elucidated（S/Fe@Biochar）,and the effects of sulfur iron ratio,additional electron shuttle(vitamin B₁₂),material aging time and coexisting ions in solution on the removal performance were explored.Sodium thiosulfate was used as sulfur source to modify the material.The removal performance of 2,4-DCP by S/Fe@biochar was greatly improved.At the dosage of 0.5 g/L and reaction time of 2 h,the removal rate of 2,4-DCP by S/Fe@biochar was 90%,while that of Fe@biochar was only 64%.The dechlorination effect of S/Fe@biochar on 2,4-DCP is nearly double that of Fe@biochar,which is due to the more stable electron transfer provided by the pyrite on the surface of the material,the inhibition of hydrogen production and the promotion of dechlorination.The results show that the removal efficiency is close to100%when the S/Fe ratio is 0.2.Then,the effect of vitamin B₁₂on the degradation of 2,4-DCP was explored.By adding a small amount of vitamin B₁₂,the difference of removal rate was compared.The results showed that the removal rate of 2,4-DCP was further improved after the addition of vitamin B₁₂,because vitamin B₁₂could release a large number of free electrons in the reaction process,thus promoting the removal of2,4-DCP.The aging time analysis of S/Fe@biochar shows that the material has a certain influence on the pollutant removal performance for long-term storage,and the removal capacity decreases with the increase of aging time.In order to be more close to the actual water,the effect of Ca²⁺on the removal of 2,4-DCP was detected.The results showed that the addition of Ca²⁺inhibited the removal of 2,4-DCP.