Study On The Treatment Of High Concentration Of Pb²⁺ By Styrene-maleic Anhydride Copolymer And Its Microspheres

Lead ion wastewater pollution is one of the most serious environmental problems.Lead ions not only cause great damage to the organisms in the environment,but also cause irreversible damage to the human body when enriched in the human body.Therefore,the discharge of lead ions in industrial wastewater is strictly regulated standards.The adsorption method is widely used in lead ion wastewater treatment methods due to its simple operation and easy separation of adsorption products from water samples.Among them,polymer adsorbents are one of the commonly used adsorbents,but many adsorbents face high concentrations of adsorbents.When treating lead ion wastewater,it is often impossible to treat lead ions below the national discharge standard(1mg/L).For this reason,this article uses styrene-maleic acid complex copolymer to study the treatment of high concentration lead ions.Styrene-maleic acid is equipped with abundant acid anhydride groups,which can generate carboxylates under hydrolysis in lye.Carboxylate has a good adsorption effect on heavy metal ions.This article studies the removal of lead ions from several aspects such as the ratio of styrene maleic acid crisp copolymer,the adsorption process of lead ions,and the modified styrene-maleic acid complex polymer microspheres,aiming to solve the problem of how to reduce the high concentration of lead ions.After fewer steps,it reaches the national emission standard.The research of this thesis is mainly divided into four parts.1)The influence of process conditions on the initial concentration of 1000mg/L lead ion treated with St:MAH=1:1 10wt%copolymer solution was explored.The results showed that the copolymer solution has a good removal effect on 1000mg/L of lead ions,up to 96%,but the amount of copolymer should not be too much.Too much amount of copolymer can cause the polymer chain to fail to settle and ultimately make the removal effect bad.The study of p H,initial concentration,and fractional precipitation conditions for the removal of 1000mg/L lead ions found that the best adsorption p H should be kept between 7.0.Excessive p H will cause Pb(OH)₂precipitation,which is unfavorable to the final result.When the concentration is above3000mg/L,a more serious gel effect will occur.By increasing the adsorption time,stirring rate,and changing the way of adding the polymer solution,most of the gel can be eliminated.Resulting in a reduction in the final removal rate.Through the use of adsorption kinetic simulation,it can be seen that the adsorption of the copolymer St:MAH=1:1 on lead ions conforms to the quasi-secondary adsorption kinetics,indicating that chemical adsorption is the main role in the adsorption process,and adsorption can reach adsorption equilibrium within 10 minutes..Through the Langmuir and Freundlich two adsorption isotherm model simulations,it can be seen that the adsorption satisfies the Freundlich isotherm adsorption model,indicating that the adsorption is a multi-molecular layer in the adsorption process.2)Experiments prove that St:MAH=1:1 10wt%copolymer solution cannot process the initial concentration of 1000mg/L lead ions to below 1mg/L in one step.In order to further reduce the concentration of lead ions,the experiment in this chapter uses St:MAH=3:1 0.5wt%copolymer solution was used to process lead ions with an initial concentration of 50mg/L.By studying the conditions of initiator dosage,copolymer solution dosage,initial concentration and other conditions for the preparation of copolymer,it is found that the copolymer with the initiator dosage of1wt%during the preparation of copolymer has the best effect on the removal of 50mg/L lead ions,and the removal of lead ions The rate first increases and then decreases with the amount of copolymer.The initial concentration of lead ions is between 20-100mg/L.The copolymer St:MAH=3:1 can reduce the final lead ion concentration to 20-30mg/L between.According to the adsorption kinetics and adsorption isotherm simulation of the copolymer St:MAH=3:1 to 50mg/L lead ions,it can be seen that the adsorption can reach the adsorption equilibrium in 10min,and the adsorption satisfies the quasi-secondary adsorption kinetics and Langmuir model.3)The second part of the experiment shows that for a 50mg/L lead ion solution,the use of St:MAH=3:1 0.5wt%copolymer solution cannot achieve the expected effect.Therefore,this chapter uses styrene-maleic anhydride to modify It is prepared into polymer microspheres,and the polymer microspheres are further used for the removal of lead ions with an initial concentration of 20 mg/L.The copolymer structure of St:MMA:MAH=5:4:1.5 was determined,and the microspheres were prepared by solvent evaporation method.Conductometric titration of the microspheres shows that the carboxyl group content of the microspheres is 3.26 mmol/g.When the amount of polymer microspheres is 10mg,the final concentration of lead ions can be reduced to less than 1mg/L.Continue to increase the amount of polymer microspheres,and the removal rate of lead ions can reach more than 99%,and the final lead ion concentration is reduced to 0.13mg/L.The initial lead ion concentration is between 20-70mg/L,and the polymer microsphere treatment can reduce the lead ion concentration below 1mg/L.After five times of repeated use of polymer microspheres,the adsorption capacity of the microspheres is still above 95mg/g.Through the adsorption kinetics and adsorption isotherm simulation of the polymer microspheres adsorbing lead ions,it is known that the adsorption satisfies the quasi-secondary adsorption kinetics and the Langmuir adsorption isotherm model,and the adsorption can reach the adsorption equilibrium within 30 minutes.4)After the first three parts of exploration,it was found that when the initial concentration of lead ion solution is 1000mg/L,the remaining lead ion concentration can not be processed to less than 1mg/L using one-step treatment.To this end,a combined process for the treatment of high-concentration lead ion wastewater was established.The combined process is divided into two steps.First,the high-concentration wastewater is treated with the copolymer solution,and then the polymer microspheres are used for complete removal.The combined process was used for preliminary research on the treatment of copper ion solution with an initial concentration of 100-1000mg/L,and the results showed that the residual concentration of copper ions can be reduced to 0.5mg/L after the initial treatment of copper ions with an initial concentration of 100-1000mg/L.the removal rate can be as high as 99%or more.