Novel porous carbon microtubes and microspheres produced from poly(CL-b-VbC) triarm block copolymer as high performance adsorbent for dye adsorption and separation

Abstract

Dandelion-like and microtube-containing novel porous carbons were synthetized from brush type poly (ε-caprolactone-b-4-vinyl benzyl chloride) (poly(CL-b-VbC)) triarm block copolymer with KOH (PCLVbK) and ZnCl2 (PCLVbZn) through optimized chemical activation at low temperature. These porous carbons were used for the adsorption and separation of cationic Malachite green (MG) and anionic Congo red (CR) and Methyl orange (MO) dyes. The synthetized porous carbons were characterized by SEM, N2 adsorption-desorption isotherms, FTIR, Raman and XRD. PCLVbK and Zn porous carbons were quite effective in cationic (MG) dye adsorption from aqueous solution thanks to different functional groups, surface areas and pore volumes. The MG adsorption capacities of PCLVbZn and PCLVbK were found to be 1684 mg/g and 869.5 mg/g, and these results are considerably higher than the other adsorbents studied in the literature. Also, it was determined that while PCLVbZn could adsorb both cationic and anionic dyes, PCLVbK could only perform the adsorption of cationic dyes. The kinetic studies conducted with MG showed that both PCLVbK and Zn porous carbons fitted better with the pseudo-second-order model. At the end of the adsorption equilibrium studies, it was observed that PCLVbZn fitted with both the Langmuir and Freundlich adsorption models while PCLVbK fitted better with the Langmuir model. In conclusion, it was observed that PCLVbK could perform high and fast adsorption and separation owing to its oxygen functional groups, while PCLVbZn turned out to be effective in the adsorption of both anionic and cationic dyes thanks to its large surface area (1006 m2/g) and empty microtubes. Based on these results, it can be argued that PCLVbK and Zn porous carbons are promising adsorbents for both high adsorption and effective separation from aqueous solution.