| With the continuous development of the economic,the shortage of water resources and the deterioration of the environment have become two basic problems that plague human beings,especially the water resources that human beings rely on.Heavy metal pollution in water caused by mining,metal smelting,metal processing and chemical production has aggravated the shortage of water sources,and threatened the health of animals,plants and human beings.Traditional treatment methods for water pollution include biological treatment,chemical precipitation,ion exchange,etc.,but these technologies limit their social use value due to high cost,complicated operation and secondary pollution.Therefore,it is necessary to find a low-cost,simple operation,no secondary pollution technology for the recovery of heavy metals in wastewater.Electrochemically switched ion exchange(ESIX)system,simple operation,high stability,and avoid the film regeneration process to produce secondary pollution,is a kind of the development potential technology.The core of this technology is to find new types of electroactive ion exchange materials(EXIMs),which has a good conductivity and high ion exchange capacity for one or several target ions.In recent years,the research on sulfur-containing materials has become a hot topic for the removal of heavy metals from wastewater.In this paper,2,2'-dithiodibenzoic acid(DTSA)containing S-S bond was used to remove heavy metals from wastewater.Due to the S-S bond of the center of the DTSA makes two terminal benzene ring to rotate freely,which maintains the stability of the "L" configuration.In this paper,the material was combined with ESIX technology,the S-S bond were broken/restructured and captured/released with objective ion at the process of oxidation reduction.In addition,sulfur atoms and heavy metal ions were more likely to form complexes,which made the material conducive to the removal of heavy metals.In this study,2,2'-dithiodibenzoic acid(DTSA)was doped into polyaniline(PANI)chain by one-step cyclic voltammetry(CV)5 and an electroactive material was successfully prepared on carbon paper,which exhibited high selectivity to cadmium ions at a ratio of 2:3.Through the study of adsorption mechanism,it was found that S and O in DTSA jointly acted on the target to achieve ion removal,and the results were verified theoretically by density functional theory.The change of electron cloud density of S and O atoms played a synergism role in the target ion uptake.The experimental results show that the DTSA/PANI hybrid film has strong combining ability to Cd2+ ions,and can effectively remove the objective ions as probes under the interference of other ions.It is worth that ion exchange capacity of hybrid film was increasing gradually with the increase of cycles,and the regeneration rate maintained at a high level.Therefore,this potential response drive film should have great potential to be applied for the removal and recovery of Cd2+ions from industrial wastewater.In order to further explore the mechanism of of DTSA doped in active materials for the removal of metal ions,a DTSA-doped polypyrrole(PPy)material was successfully prepared to remove silver ions from wastewater by double pulse method in this study.The results show that the S-S bond in 2,2'-dithiobenzoic acid exhibits electronegativity and improves the exchange capacity of Ag+ ions with a synergistic role in potential driving force.In this experiment,only S acted on the target ion,while O atom did not participate in the reaction.The experimental results show that the hybrid film has a good removal effect on the low concentration solution,and can perform well on Ag+selectivity in the presence of other cations.In addition,the regeneration rate of the composite film can still maintain above 70%after multiple cycles. |
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