Study On Synthesis Of Granular Poly(Acrylic Acid-sodiumacrylate) Bentonite Composite By Means Of Suspension Polymerization And Tis Properties

At present, there are a lot of reports about the preparation methods of compositebentonite adsorbents, which exist in the integrated block structure. It has some problemsremain unresolved, for example the product is difficult to takeout and it also need togrinding. In this paper, a new of granular poly(acrylic acid-sodium acrylate) bentonitecomposite by means of suspension polymerization, and its properties were investigated.According to the dissolution quantity of acrylic acid and the adsorption capacity ofCd2+,we get the optimal conditions:polymerization temperature is70℃, polymerizationtime is3h, the ratio of cyclohexane and span80is52.5:2.5,the oil/water ratio is100:15.Through the characterization of raw materials and products by XRD,IR and SEM, themechanism of copolymerization was discussed. The results show that acrylic acid,sodiumacrylate and bentonite happen to intercalation polymerization, and do not destroy the basicstructure of bentonite. Experiments were conducted to investigate the bentonite compositeturbidity, It showed that the secondary turbidity value0.47NTU had been met nationalstandards(0.5NTU).Adsorption and regeneration experiments were conducted, and Lagergren fitting wasmade on adsorption process, Langmuir fitting and Freundlich fitting were made onadsorption equilibrium. The results showed that bentonite composite had a significantadvantage over bentonite in respects of adsorption properties for Cd2+, Pb2+and F-, and itwas better than bentonite in respects of regeneration properties for F-,but poor adsorptioneffect for Cr6+. There is an error in measuring method of chloroacetic acid adsorption andthe product dissociation, The adsorption processes for cadmium and lead ions werecorresponding with the Langmuir isotherm equation. When initial concentrations ofcadmium and lead ions solution were100mg/L and80mg/L, the maximum adsorptioncapacities of Langmuir fitting were19.56mg/g and8.998mg/g, respectively. Theadsorption process of fluorine ions was corresponding with the Freundlich isothermequation, it shows that adsorption process of fluorine ions is a type of transitional chemicaladsorption, and the adsorption capacity was0.91mg/g for50mL initial concentration of16.3mg/L by0.5g bentonite composite products.In order to study the dynamic adsorption process and regeneration of bentonite composite for fluorine ions, fixed bed experiments were carried out. Under the conditionsof bed height of13cm, flow rate of7mL/min, the handling capacity of fluorine ions withinitial concentration of79.8mg/L was6L, the highest removal rate was46.12%. Theregeneration of bentonite composite for fluorine ions showed that, under the initialconcentration of79.8mg/L，the lowest concentration of bed export was0.121mg/L and theremoval rate was99.85%, regeneration effect was ideal. Appropriate regeneration methodwas still to be further studied.