Adsorption of Sulfamethazine from Environmentally Relevant Aqueous Matrices onto Hypercrosslinked Adsorbent MN250

Four hundred tons of sulfamethazine are fed to livestock annually in North America for disease prevention and growth promotion, but the majority is excreted unmetabolized into the environment. Due to its slow degradation and high mobility, sulfamethazine contaminates groundwater and causes aquatic ecosystem damage. Sulfamethazine remediation methods are not universally effective, necessitating newer techniques. Hypercrosslinked polystyrene adsorbents show promise because of high surface areas, durability, and regenerable properties. Using batch techniques, sulfamethazine adsorption onto Purolite MN250 was evaluated in the presence of dissolved humic acid and under variable pH and ionic strength. The adsorption capacity () of MN250 for sulfamethazine with humic acid was 109.3 mg g. In simulated groundwater, at pH 5 was 51 to 62% higher than at pH 9. The maximum at pH 7 (144.0 mg g) exceeded pH 5 performance (128.3 mg g). In 0.005 M KCl, was 181.0 mg g, which decreased by 34% in 0.05 M KCl. In 0.5 M, KCl, (153.4 mg g) increased 26% over 0.05 M KCl. For all matrices, equilibration was attained between 120 and 168 h, best fit by Ho's pseudo-second-order model. Overall, is pH dependent because the sulfamethazine speciation and the zeta potential of MN250 vary as a function of pH. Increasing ionic strength initially decreases by altering the activity coefficient of sulfamethazine and by altering the properties of the electrical double layer, while salting-out becomes prominent at seawater concentration. MN250's high sulfamethazine capacity in environmentally relevant aqueous matrices highlights its potential for groundwater remediation.