Alkaline modified biochar derived from spent coffee ground for removal of tetracycline from aqueous solutions

The feasibility of applying alkaline modified-biochar prepared through pyrolysis of spent coffee ground (NaOH-SCG) in the elimination of tetracycline (TC) from different aqueous solutions was investigated through this study. The physico-chemical characterization of NaOH-SCG was scrutinized by distinct techniques. The PAHs concentration of NaOH-SCG (500 °C) was 693 μg kg−1, which do not exceed the international acceptable threshold of PAHs in biochar as reported by International Biochar Initiative (6–20 mg kg−1) and European Biochar Certificate (4 mg kg−1 for premium class, 6 mg kg−1 for basic class). From the experimental results, the adsorption capacity (qmax) of NaOH-SCG biochar (113.64 mg g−1) exhibited 2.9 times higher than that of the non-modified SCG (39.22 mg g−1). Furthermore, environmental factors, namely, pH and ions, affecting the interaction between biochar and TC was investigated. Alkaline modified-biochar exhibited high tetracycline adsorption capacity and therefore has a great prospect as an environmentally effective adsorbent in separation of hazardous chemicals from different aqueous solutions.