Applicability of TiO2(B) nanosheets@hydrochar composites for adsorption of tetracycline (TC) from contaminated water

We test the feasibility of TiO 2 (B)@carbon composites as adsorbents, derived from wheat straws, for tetracycline (TC) adsorption from aqueous solutions. Hydrochar (HC), biochar (BC), and hydrochar-derived pyrolysis char (HDPC) are synthesized hydrothermally from the waste and then functionalized with TiO 2 (B), named as ‘Composite-1′, ‘Composite-2′, and ‘Composite-3′, respectively. A higher loading of TiO 2 (B) into the HC was also synthesized for comparison, named as ‘Composite-4′. To compare their physico-chemical changes before and after surface modification, the composites are characterized using FESEM-EDS, XRD , BET, FRTEM, and FTIR. The effects of H 2 O 2 addition on TC removal are investigated. Adsorption kinetics and isotherms of TC removal are studied, while TC adsorption mechanisms are elaborated. We found that the Composite-4 has the highest TC removal (93%) at pH 7, 1 g/L of dose, and 4 h of reaction time at 50 mg/L of TC after adding H 2 O 2 (10 mM). The TC adsorption capacities of the Composite-1 and Composite-4 are 40.65 and 49.26 mg/g, respectively. The TC removal by the Composite-1 follows the pseudo-second order. Overall, this suggests that converting the wheat straw into HC and then functionalizing its surface with TiO 2 (B) as a composite has added values to the waste as an adsorbent for wastewater treatment .