Decontamination of tetracycline by thiourea-dioxide-reduced magnetic graphene oxide: Effects of pH, ionic strength, and humic acid concentration.

Thiourea-dioxide-reduced magnetic graphene oxide (TDMGO) was successfully prepared as an efficient adsorbent for the removal of tetracycline (TC) from aqueous solutions via strong adsorptive interactions. The composite was characterized by SEM, TEM, EDS, TGA, FT-IR, XPS, XRD and VSM. The effects of variables such as the pH, TC concentration, and temperature were successfully analyzed. The kinetics and isothermal parameters were described well by pseudo-second-order and Langmuir isotherm models, respectively, and the maximum adsorption capacity (qm) of TDMGO for TC calculated from the Langmuir isotherm was 1233mg/g at 313K. The removal of TC onto TDMGO, as indicated by the thermodynamic parameters, was spontaneous and endothermic. The removal performance was slightly affected by the solution pH. The presence of NaCl in the solution facilitated TC adsorption, and the optimum adsorption capacity was obtained when the NaCl concentration was >0.001M. The adsorption capacity decreased slightly with increasing humic acid concentration. In addition, the adsorbent could be regenerated and reused. Based on these results, TDMGO is a promising adsorbent for the efficient removal of TC antibiotics from aquatic environments for pollution treatment.