Removal of Hydroxychloroquine Using Engineered Biochar from Algal Biodiesel Industry Waste: Characterization and Design of Experiment (DoE)

Adsorption of hydroxychloroquine (HCQ) onto H(3)PO(4)-activated Cystoseira barbata (Stackhouse) C. Agardh (derived from algal biodiesel industry waste) biochar was investigated via batch experiments and mathematical models. The activated biochar (BC-H) was produced in a single step by using the microwave irradiation method. Thus, it was obtained with a low cost, energy efficiency and by promoting clean production processes. BC-H exhibited a remarkable adsorption efficiency (98.9%) and large surface area (1088.806 m(2) g(−1)) for removal of HCQ. The Langmuir isotherm and the pseudo-second-order kinetic models were the best fit for the equilibrium adsorption and kinetics experiments, and the maximum monolayer adsorption capacity (qmax) was found to be 353.58 µg g(−1). Additionally, the experiments with real wastewater showed that BC-H's ability to adsorb HCQ was not affected by competitive ions in the water. The Taguchi orthogonal array (L16 OA) experimental design was applied for the effective cost optimization analyses of the adsorption process by considering four levels and four controllable factors (initial pH, HCQ concentration, amount of adsorbent and contact time). Scanning electron microscopy, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller analyses were used for characterizing the adsorbent. The findings showed that BC-H can be used as an effective and low-cost adsorbent in the removal of HCQ from water. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13369-021-06235-w.