| With the development of national economy and the improvement of living standards for people, thePVC demand was increased year by year. Meanwhile, the manufacturing process wastewater of PVCproduction by calcium carbide process contains mercury after treatment, as a result, it has an importantsignificance that to solve the growing problem of mercury pollution. Adsorption as a mature technology toremove heavy metal pollution is widely used. The traditional adsorption materials of coal-based activatedcarbon (CBAC) and novel composite adsorption material pectin/titanium pillared bentonite (PTPB) werestudied in present study. On one hand, based on rich in coal resources in Xinjiang, CBAC was prepared byQue Er Gou anthracite as raw material and KOH as an activator were via microwave-assistance, and applyto remove mercury ion adsorption experiments; meanwhile, methylene blue (MB) is a familiar andimportant dye and its absorbance is an important indicator to evaluate performance of AC adsorption,therefore, the MB absorbance was important object of the study. On the other hand, it is a new exploratoryattempt that to preparation PTPB contains adsorption property of bentonite, flocculation property of pectinand photocatalytic property of titanium dioxide, and applied to remove mercury ion adsorption experiments.Experimental results were as follows:(1) Anthracite from Que Er Gou in Xinjiang as raw material and KOH as an activator to preparation ofCBAC was studied and optimium preparation condition was definited though the single factor andresponse surface. The experimental results showed that the optimium preparation condition viamicrowave assisted was the alkali/coal ratio of1:1, microwave power637W and irradiation time of9min, the corresponding optimal iodine and MB adsorbacne were804.96mg/g and126.34mg/g，respectively. The results of characterization indicated that the CBAC was mesoporous and own hugespecific surface area, developed pore structure, a lot of oxygen-contain and acidity surface.(2) The MB adsorption study was investigated on resultant CBAC. The influences of MB adsorbance oninitial concentration and pH were investigated. The isotherm adsorption model, adsorption kinetics andadsorption mechanism through adsorption data were researched. The experimental results indicated theMB adsorbance increased with increasing initial concentration and pH. The process was fitted toRedlich-Peterson adsorption isotherm and pseudo-second-order kinetic model indicated that theadsorption process is monomolecular layer and adsorption multilayer adsorption，and chemicaladsorption step is rate-limiting step. The intraparticle diffusion is not only the rate-limiting step, butalso the membrane diffusion in adsorption process through adsorption mechanism model.(3) The Hg(Ⅱ) adsorption study was investigated on resultant CBAC. The influence of initialconcentration, activated carbon dosage, temperature and pH on removing Hg(Ⅱ) and the adsorptionisotherms and kinetic models were studied. The experimental results illustrated the optimiumadsorption conditions of CBAC for Hg(Ⅱ) was activated carbon dosage of0.05g, initial concentrationof100mg/L, temperature of20oC and pH of8~10, the corresponding maximum Hg(Ⅱ) adsorbacnewas53.40mg/g. The Langmuir isotherm model and pseudo-second-order kinetic model were harmonious with CBAC adsorption on Hg(Ⅱ), demonstrated the adsorption process is the monolayeradsorption and chemical adsorption process is the rate-limiting step.(4) The PTPB was prepared and applied removal of Hg(Ⅱ) successfully. The characterization results andexperiments showed that the PTPB owned good anatase and apply to photocatalytic degradation. Aftercomposite with pectin, the amount of composite increased, specific surface area decreased and Hg(Ⅱ)adsorbance descreased.The CBAC traditional adsorption material and PTPB novel composite material were preparedsuccessfully, and proved the two adsorbents effectively remove Hg(Ⅱ), which seeks to a low-cost and nosecondary pollution alternative adsorbents for removing residual Hg(Ⅱ) on PVC production by calciumcarbide process, meanwhile, the present study also provides a reference for other treatment of wastewatercontaining other heavy metals. |
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