Bamboo-derived biochar as an efficient adsorbent for oxytetracycline removal from water

Abstract

The increasing presence of oxytetracycline (OTC) in water sources due to its extensive use in aquaculture and livestock rearing necessitates effective removal techniques. We evaluated the adsorption performance of two forms of bamboo-derived biochar, one produced through CO₂ activation (B1) and the other produced through steam activation (B2), in both batch and continuous systems. The results showed that bamboo-derived biochar exhibited low ash content and high fixed carbon, with the biochar produced by steam activation (B2) demonstrating better porosity, as evidenced by lower bulk density and bee-hive structures observed in the SEM images. Batch experiments showed that B2 exhibited a higher maximum adsorption capacity (34.3 mg/g) compared to B1 (21.5 mg/g) under optimized conditions. Continuous column experiments revealed that B2 achieved superior performance, with a breakthrough time of 50 h and a maximum adsorption capacity of 100 mg/g, significantly higher than B1's breakthrough time of 20 h and capacity of 44 mg/g. Under re-used conditions, B2 out-performed B1 with Ce/C₀ stabilizing at ∼0.1, compared to ∼0.4 for B1, highlighting the enhanced efficiency of B2 over repeated cycles. However, after regeneration using distilled water, both materials exhibited a significant decline in adsorption performance, with Ce/C₀ values exceeding 0.8, indicating the ineffectiveness of the regeneration method. These results emphasize the structural advantages of B2, contributing to its superior adsorption performance in both batch and continuous systems. Despite these strengths, the limited reusability of both materials underscores the need for optimized regeneration protocols.