Effective removal of tetracycline from water by batch method using activated carbon, magnetic carbon nanocomposite, and membrane hybrid technology

Abstract

Abstract In this study two adsorbents (activated carbon; AC and magnetic activated carbon; MCN) were prepared from Dalbergia sissoo sawdust and used as potential adsorbents for the removal of tetracycline (TC) from water. Both the adsorbents were characterized by instrumental techniques like energy dispersive x-ray (EDX), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), x-ray diffraction (XRD), surface area analyzer and thermal gravimetric/Differential thermal analysis (TG/DTA). The effect of antibiotic initial concentration, contact-time, pH, adsorbent-dose, and temperature were evaluated to determine optimum adsorption conditions. The optimum TC concentration for both AC and MCN was 120 mg/L while optimum time of saturation for both adsorbents was 120 min. The optimum pH determined was five while optimum adsorbent dose was 0.1 g. The adsorption isothermal data of both sets of experiments was best explained by Langmuir model. The kinetic data was well explained by pseudo-second order kinetics model. The ΔH° (enthalpy change) and ΔSo (entropy change) were; −14.989 and 25.174 kJ/mol for AC and −11.628 and 51.302 kJ/mol for MCN respectively. The values of Gibbs free energy (ΔG°) calculated for AC were 7.36, −7.99, −7.36, −7.61, and −8.12 kJ/mol while for MCN these were −15.02, −15.53, −16.05, −16.56, and −17.07 kJ/mol corresponding to temperatures; 298, 303, 313, 323, and 333 K. To control fouling in ultra-filtration, nano-filtration, and reverse osmosis membranes caused by TC, and both adsorbents, a continuous stirred reactor was connected in series with membrane pilot plant. The improvement brought about by both adsorbent in parameters like % retention and permeate flux was also evaluated. Comparatively, better improvement was brought about in % retention and permeates flux by MCN.