Investigation of mechanisms of sulfamethoxazole adsorption on novel adsorbents developed from reed canary grass

Abstract

In this work, reed canary grass and activated carbons developed from this biomass were used as novel adsorbents to remove sulfamethoxazole (SMX) from water. Raw biomass adsorbent with the lowest surface area demonstrated the lowest SMX adoption capacity of 20.2 ± 1.6 mg/g and the activated carbon adsorbent with the highest surface area showed the highest adsorption capacity of 160.5 ± 4.2 mg/g. π-π, hydrogen bonding, Lewis acid base, and hydrophobic interactions are the possible mechanisms that could be responsible for adsorption of SMX on the adsorbents. Methanol, hydrochloric acid solution, sodium hydroxide solution, and deionized water were used to desorb SMX from the adsorbent. The results of using 20 mL of solvent at 35 °C showed that methanol could desorb loaded SMX with a higher desorption efficiency (80.1 ± 2%) than the aqueous solvents (9.5-46.5%). Decreasing the temperature to 25 °C decreased the desorption efficiency of methanol to 58.5 ± 1%. By decreasing the methanol volume to 5 mL, SMX desorption efficiency could remain comparable (59.1 ± 1.2%). Reusing the adsorbent in 4 adsorption desorption cycles showed that SMX adsorption capacity reduced from 124.9 ± 3.8 mg/g in the first adsorption cycle to 82.1 ± 2.2 mg/g in the second adsorption cycle and was stable in the third and fourth cycles.