Effect of Acid Soaking on Properties of Zeolite-Based Porous Carbon Composite Prepared for Adsorption of Cationic Dye

Novel zeolite-based porous carbon (ZC) composites derived during direct pyrolysis of chitosan and polyacrylic acid as carbon sources and of zeolite as a template followed by acid soaking of HCl and HF were studied. Characterization tools including SEM, XRD, FTIR and N2 adsorption–desorption measurements were employed to assess the effect of acid soaking on the surface and adsorption properties of products (ZC-HCl and ZC-HF). Adsorption of methylene blue (MB) cationic dye was examined to evaluate the adsorption capacities of ZC-HCl and ZC-HF composites. SEM, XRD and FTIR analyses proved that soaking with HCl acid (ZC-HCl) could be removed large amounts of zeolite and formed functional groups with positively charges on the carbon surface. Whereas soaking by HF acid (ZC-HF) influenced slightly on the surface and morphology of zeolite-carbon composite with maintaining negatively charges confirming the attachment of zeolite on the carbon surface. Total surface areas as high as 170 and 241 m2/g were obtained for ZC-HCl and ZC-HF, respectively. Langmuir isotherm could be fitted the adsorption of dye. It was found that equilibrium adsorption capacities of MB at 25 °C and pH 6 were 45.5 and 83.6 mg/g onto ZC-HCl and ZC-HF, respectively. Kinetic data were well-described by pseudo-second order model and consequently the chemisorption powered the adsorption process over the sample's surface. Therefore, the obtained ZC-HF sample is considered to be a potential adsorbent for removing cationic dyes.