Study On Enhanced Composite Polymer/Iron Oxide Multifunctional Adsorbent Preparation And Application

Now,the pollution problem of antimony in drinking water is increasingly serious.Antimony(Sb)in water presents various serious environmental hazard and it lacks established methods for its effective removal.In this study,a specific composite adsorbent(CS/CA-Fe)has been prepared to remove the trace antimony by using hydrated ferric oxide(Fe)loaded in chitosan(CS)and cellulose acetate(CA)blend porous substrate.FTIR and XRD analysis verified the composite formulation of the prepared adsorbent,SEM images and BET method clearly demonstrated its porous structure and the physical properties,and some other methods analyzed and measured surface potential,Fe loading and so on.CS/CA-Fe was examined for the removal of Sb(V)in water under various solution dosages,pH values,adsorption time,adsorption temperature,ionic strength and the coexisting ionics,as well as for its adsorption kinetics,adsorption isotherm and major adsorption mechanisms by XPS analysis.The charaaterizations verified that iron oxide particles uniformly loaded in the copolymer CS/CA,and was in the form of HFO.The loaded iron oxides was loading in not only physical but also chemical forms.The isoelectric point of CS/CA-Fe is near the pH6.5.It is concluded that the amount of chitosan increasing can reduce the material mechanical strength through the experiment of the swelling rate.The iron content of our research is higher than the methods of the iron salts solution evaporation and Sengupta A.K..The results of the adsorption experiments showed that CS/CA-Fe had good performance,and at pH4,it reduced Sb(V)from 200 ?g/L to lower than 5 ?g/L,less than that required by “Sanitary Standard for Drinking Water”.The adsorbent had very fast initial uptake rate and reached adsorption equilibrium usually within 12 h.Adsorption performance was affected by solution pH values and under acidic pH the performance was greatly enhanced.The adsorption process appeared to be exothermic but the effect of temperature seemed to be relative small.The experiments of ionic strength and coexisting ions showed that with the increasing of ionic strength and the addition of the coexisting ions,the adsorption effect of Sb(V)by CS/CA-Fe weakened.The experiments of reuse and regeneration showed that the regeneration effect to adsorbing antimony is good using NaOH solution.And the increasing of NaOH concentration,the regeneration efficiency was increasing.For example,the regeneration effect can reach 97% by 1M NaOH solution.However,the adsorption performance by using a high concentration of NaOH solution to regenerat adsorbent was not ideal.It is possible that the NaOH solution caused a certain destruction to the composite material.It needs to be further discussed.The adsorption kinetics was well fitted by the pseudo second order kinetic model.In further using the internal diffusion and Boyd model fitting for adsorption dynamics,the pH4 results concluded that the adsorption rate is mainly affected by the external diffusion.It showed that the enrichment of adsorbent to antimony also played an important role in the adsorption process.It also confirmed that the theory which the protonation effect of the chitosan with antimony in water produced the electrostatic attraction is reasonable and the adsorption process conforms to the donnan membrane effect.Experiments showed that when low initial antimony concentration,the adsorption rate was mainly affected by porous diffusion at pH6.5.The cause is the composite adsorbent didn't have static enrichment to antimonate,and the effect of external diffusion and interface layer diffusion is smaller than the porous diffusion effect is small.So the adsorption rate was slow.Both the Langmuir and Freundlich models described the isothermal adsorption curves adequately,with the adsorption capacity given at 43.6mg-Sb(V)/g-CS/CA-Fe.The XPS analysis showed that the reaction of the physical and chemical of the composite adsorbent CS/CA-Fe removing antimony was not related with iron oxide and also with chitosan.It can be concluded that the good adsorption performance of CS/CA-Fe to Sb(V)was due to a number of factors,including the enrichment of Sb(V)by protonated CS in the region near CS/CAFe,the inner-sphere adsorption of hydrated ferric oxide,and the porous structure of CS/CA-Fe formed by the CS/CA blend substrate.In addition,the external enrichment effect of composite adsorbent polymer to trace antimony in water improves the diffusion limitation of the low concentration of antimony in water to the adsorbent.The study shows the great potential in the practical application of CS/CA-Fe for the removal of trace Sb(V)in water.