Adsorption of amoxicillin by Mn-impregnated activated carbons: performance and mechanisms

Phragmites australis carbon (PAC) was produced from Phragmites australis by phosphoric acid (H3PO4) activation. To achieve a better amoxicillin (AMX) adsorption performance, manganous dihydrogen phosphate (Mn(H2PO4)(2)) and manganese chloride (MnCl2) were impregnated, producing PAC-MP and PAC-MC, respectively. Adsorption studies were carried out in different initial AMX concentration (15-100 mg L-1), pH (2-10) and contact time (0-60 h) to evaluate AMX adsorption performance and mechanisms. The adsorption isotherms well agreed with the Langmuir model for the three adsorbents. The maximum AMX adsorption capacity on PAC, PAC-MP and PAC-MC was 110, 132 and 122 mg g(-1), respectively. Solution pH had a strong influence on AMX adsorption. For kinetic results, a significant desorption phenomenon was observed. Several possible mechanisms were elaborated which include electrostatic interaction, complexation and degradation of AMX molecules. On the whole, Mn-impregnated PAC showed superior AMX removal efficiency, which presents a promising modification method for activated carbon in the treatment of AMX containing wastewater.