Effect of solution pH and coexisting ions on cefradine adsorption onto wheat straw

Agricultural waste wheat straw was innovatively used for the adsorptive removal of cefradine. The aim of this study is to assess the adsorption behaviour of wheat straw for cefradine removal from the wastewater. Effect of solution pH and coexisting ions was investigated concurrently. Typical kinetic models including pseudo-first-order, pseudo-second-order and Elovich models were used to simulate adsorption kinetics at different pH conditions. Kinetic experiments indicated that both the linear and nonlinear pseudo-second-order kinetic models could describe the adsorption kinetics better. It can be inferred that chemisorption occurred between the cefradine molecules and the wheat straw. It is worthy to mention that most of the uptake occurred within the initial 60 min, indicating a fast removal of cefradine when wheat straw was applied in practical wastewater treatment. Ionic strength experiment demonstrated that cefradine molecules may be specifically adsorbed on the wheat straw via forming outer-sphere surface complexes. A decrease of the uptake of cefradine was observed in the presence of HCO3–, HPO42-, SO42- and SiO32-, while the inhibiting effect was in the pecking order Na2SiO3> Na2SO4>Na2HPO4>NaHCO3. The presence of humic acid could decrease the cefradine uptake as well. © 2019 Technoscience Publications. All Rights Reserved.