Research On Effect And Mechanism Of The Adsorption Of Heavy Metal Ions In The Water By Biological Compound Flocculant

In recent years,heavy metal pollution happens frequently, especially”the fivepoisons”which include Cr、Cd、Hg、Pb、As and Cu threat to human health.Thegeneral methods of treating heavy metal pollution is defective in certain areas suchas crafts,economy and so on. Flocculation’s efficiency, simple operation and lowrunning costs making it the central issue of treating heavy metal pollution.In thisstudy,we compound chemical flocculant and microorganisms flocculant intobiological flocculant to remove Cu²⁺、Cd²⁺、As³⁺、Cr⁶⁺、Pb²⁺、Hg²⁺ions from thewaste water.Not only reduce the dosage of flocculant,making it less poisonous andreducing its cost,but also improve the removal efficiency of heavy metalions.Besides, we optimizated the adsorption conditions and resolved the adsorptionmechanism.To each simulated wastewater containing heavy metals, Through a separatePAM flocculant dosing chemical and biological flocculant MBF1, MBF2adsorptionof heavy metals to determine the complex biological compound flocculant dosage.Bio-composite flocculant has higher removal efficiency than the singleflocculant.We re-dubbed MBF1and PAM as the best bio-composite flocculant toremove Cu²⁺、Cd²⁺、As³⁺and Cr⁶⁺and then re-dubbed MBF2and PAM as the bestbio-composite flocculant to remove Pb²⁺and Hg²⁺.We explored the impact of various factors on the adsorption of heavy metal.Neither high ratio nor low ratio of biological and chemical flocculant compound isconducive to the removal of heavy metals. Adsorption is not conducive in low pHrange,the best pH range is4-6. With the increase of the initial concentration ofheavy metals, when it reached adsorption equilibrium, adsorption unit increased,but at the same time, removal efficiency decreased.30℃is the optimum adsorptiontemperature.The time of reaching adsorption equilibrium is short,after reachingadsorption equilibrium，the removal rate remained unchanged or decreased slightly.Under the optimum adsorption conditions,the maximum removal rate of Cu²⁺、Cd²⁺、As³⁺、Cr⁶⁺、Pb²⁺and Hg²⁺respectively reach96.19%、97.14%、80.81%、65.47%、98.5%、52.62%.When the six kinds of heavy metal ions coexist, the ways andmechanisms of bio-composite flocculant adsorption of heavy metal ions remainunchanged. The order of adsorption is Pb²⁺＞Cd²⁺＞Cu²⁺＞As³⁺＞Cr⁶⁺＞Hg²⁺.Langmuir and Dubinin–RadushLkevich’s adsorption isotherm is applicable todescribe the adsorption process and adsorption thermodynamic results show that thesurface electrostatic effect plays a main role in the process of adsorption, Quasi secondary level1dynamic equation is applicable to study adsorption dynamics;Scanning electron microscopy and energy spectrum characterization shows thatporous structure provides a strong adsorption space structure; Ftir results can bespeculated that the hydroxyl, carbonyl, amino, carboxyl, aromatic base and otherfunctional groups involved in heavy metal ions and biological combination betweencomposite flocculant, and occured the chemical reaction.