Tuning the porosity of hypercrosslinked styrene-divinylbenzene copolymers for efficient adsorption of rifampicin from aqueous media

In this study, hypercrosslinked copolymers (HCCPs) designated as HCCP-1DVB, HCCP-2DVB and HCCP-3DVB were obtained by post-crosslinking of styrene-divinylbenzene copolymers with the various molar content of divinylbenzene (1, 2, and 3%) using chloromethyl methyl ether via the Friedel-Crafts reaction. The chemical structure, porous and morphological characteristics of hypercrosslinked copolymers were determined by FT-IR, low-temperature nitrogen adsorption-desorption method and SEM, respectively. The synthesized hypercrosslinked copolymers had high surface area values and different micro/mesoporous structures. It was found that mesopore volume increased with a decrease in divinylbenzene content in a copolymer. HCCP-1DVB had the largest mesopore volume (0.53 cm3/g), the highest adsorption capacity for rifampicin (qm = 183.27 mg/g), and the highest rifampicin adsorption rate. Adsorption capacity of HCCP-1DVB towards rifampicin is comparable with other adsorbents used for its adsorption or even significantly higher. The adsorption equilibrium and kinetic processes were well described by the Langmuir model and the pseudo-second-order model. The experimental data indicated that the removal efficiency of rifampicin reached 99.8% at the dosage of HCCP-1DVB equal to 80 mg/10 mL. The removal efficiency of rifampicin by HCCP-1DVB was higher than by some tested commercial hypercrosslinked adsorbents. After 5 cycles of reuse, the adsorption capacity of HCCP-1DVB decreased only by 7%, which indicates sufficient stability and reusability of this hypercrosslinked copolymer.