Facile fabrication of sodium styrene sulfonate-grafted ethylene-vinyl alcohol copolymer as adsorbent for ammonium removal from aqueous solution

Abstract

An adsorbent EVOH-g-SSS(H) was successfully synthesized for ammonium removal by one-step grafting SSS onto EVOH particles directly using radiation-induced grafting technique followed by protonation. The effects of adsorbed dose and monomer concentration on grafting yield were investigated. The adsorption behaviors of the EVOH-g-SSS(H) towards ammonium ions (NH₄⁺) were discussed. The adsorption isotherm of NH₄⁺ was a followed Langmuir model with the maximum adsorption capacity of 22.53 mg/g at optimal pH 6.5. For comparison, adsorption kinetics towards NH₄⁺ removal by EVOH-g-SSS(H) and commercially available DIAION PK228 were studied. Both adsorbents were better obeyed pseudo-second-order mode. EVOH-g-SSS(H) for NH₄⁺ uptake was faster than PK228 and reached equilibrium within 5 min. Column experiment showed that the column adsorption capacity of EVOH-g-SSS(H) adsorbent was 9.69 mg/g-ad at SV 10 h⁻¹. The NH₄⁺ concentration in outlet solution can maintain at a very low level even SV was as high as 800 h⁻¹. The elution curve showed the EVOH-g-SSS(H) adsorbent can be regenerated using 1 M HCl. Besides, the removal percentage of NH₄⁺ can be 97% from actual groundwater within 1 min. Such high adsorption efficiency of EVOH-g-SSS(H) makes it to be employed as an adsorbent for NH₄⁺ removal in practical application.