Synthesis of hybrid hydrogel of poly(AM co DADMAC)/silica sol and removal of methyl orange from aqueous solutions

A hybrid hydrogel (poly(AM co DADMAC)/silica sol) from acrylamide (AM), diallyl dimethyl ammonium chloride (DADMAC) and silica sol was prepared by aqueous solution polymerization, using N,N′-methylenebisacrylamide (MBA) as crosslinker and ammonium persulfate (APS) as initiator. Its structure and characterization were determined by means of FTIR, SEM, TEM and TG; meanwhile, the effects of silica sol content, pH values and temperatures were studied on the adsorption of methyl orange onto (poly(AM co DADMAC)/silica sol (PAMDS). The adsorption rate data and adsorption equilibrium data were analyzed based on the pseudo-second-order model and four isotherm models respectively. Results obtained from this study indicated that the kinetic behavior accorded with the pseudo-second-order kinetic model. The isotherm behavior can be explained by the Langmuir, Freundluich and Generalized isotherm models. The activation energy was also evaluated for the removal of methyl orange onto PAMDS. This hybrid hydrogel may be used as good adsorbent for the adsorption of anionic dyes from effluents.

Graphical abstractThe hydrogel of poly(AM co DADMAC)/silica sol was prepared through a one-step solution polymerization method, which was used as an absorbent in the removal of methyl orange. The kinetics and isotherms of adsorption were also studied.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Poly(AM co DADMAC)/silica sol is prepared by a simple one-step method. ► The removal % of dye reaches to 83% from 50% when silica sol is added. ► Strong acidic and basic conditions can greatly decrease the adsorption capacity.