Study On The Adsorption Of Several Pollutants From Solution By Iron And Pei Blended Chitosan-polyvinyl Alcohol Composite Films

By doping chitosan,Fe Cl₃·6H₂O,polyethyleneimine?PEI?and polyvinyl alcohol?PVA?,the chitosan-polyvinyl alcohol-iron composite membrane materials?CS-PVA-Fe?and the chitosan-polyvinyl alcohol-polyethyleneiminecomposite membrane materials?CS-PVA-PEI?were prepared,The adsorption capacity of the two composite membrane materials to Congo red dye?CR?,phosphate ion and Cu²⁺and Pb²⁺was studied.The isoelectric point(p H_pzc)and X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared spectrum?FTIR?,Scanning electron microscope?SEM?were used to characterize CS-PVA-Fe and CS-PVA-PEI to determine their property of surface and adsorption mechanism.Compared with chitosan?CS?membrane,CS-PVA-Fe membrane is more acid resistant,and has good adsorption capacity toward CR and phosphate under acid condition.Compared with chitosan?CS?membrane,CS-PVA-PEI membrane has higher adsorption capacity for Cu²⁺and Pb²⁺under the same conditions,while CS-PVA-Fe and CS-PVA-PEI to determine their adsorption mechanism.Composite membrane materials are resistant to existed common salts.In the static adsorption experiment,the effects of the dose of adsorbent,contact time,solution p H,coexisting ions,temperature and adsorbate concentration of solution on the adsorption process were performed.Solution p H has great influence on the four adsorption processes.Langmuir and Koble-Corrigan models are suitable for describing the adsorption process of Cu²⁺and Pb²⁺onto CS-PVA-PEI.The kinetic model fitting shows that CS-PVA-PEI conforms to the Pseudo-second-order and Elovich model.The maximum adsorption capacity of Cu²⁺and Pb²⁺is 48.2 and 88.3mg/g,The adsorption process of Cu²⁺by CS-PVA-PEI is non spontaneous,endothermic and entropy increasing process,while that of Pb²⁺is spontaneous,endothermic and entropy increasing process.Combined with the above results and XPS results,CS-PVA-PEI has coordination and ion exchange in the adsorptionThe adsorption process of CS-PVA-Fe on PO₄^3-is in accordance with Langmuir and Koble Corrigan models.The kinetic fitting results show that the adsorption process of PO₄^3-on CS-PVA-Fe is in accordance with Pseudo-second-order model,Double constant model and Elovich model,Under the condition of Langmuir fit,the maximum adsorption capacity of PO₄^3-was predicted to be about 30.0 mg/g?according to P?,the adsorption process of CS-PVA-Fe and the process is spontaneous,exothermic with decrease of entropy.Combined with the above and XPS results,it shows that there are coordination and electrostatic attraction in the adsorption process of CS-PVA-Fe on PO₄^3-.The adsorption process of CR by CS-PVA-Fe accords with Langmuir model.The results of kinetic fitting showed that the adsorption process of CS-PVA-Fe for CR was in accordance with the Pseudo-first-order,Pseudo-second-order and Elovich models.The maximum adsorption capacity of CR is 421 mg/g,The thermodynamic datas shows that the adsorption process of CR is spontaneous,endothermic with the increase of.Combined with the above and XPS results,the adsorption process of CS-PVA-Fe on CR has the functions of electrostatic attraction,ion exchange and complexation.The regeneration experiment shows that 75%medical alcohol in alkaline environment can desorb the adsorbed CR by CS-PVA-Fe,and the regeneration effect of CS-PVA-Fe is good,but the regeneration ability of CS-PVA-Fe to PO₄^3-is poor,and the regeneration ability of CS-PVA-PEI to Cu²⁺and Pb²⁺is the worst.The results can offer the basic information for the films to remove pollutants from solution.