ABSTRACT

The present study focused on the usability of scallop shell coated Fe₂O₃ nanoparticles as an eco-friendly new absorbent in the treatment of tetracycline (TC). The process performance in terms of TC removal was investigated at different operating conditions, i.e. at solution pH of 3–11, Fe₂O₃-scallop dosage of 0.4–2.4 g L⁻¹, initial TC content of 20–120 mg L⁻¹ and temperature of 25–55°C. Solution pH of 7 yielded the highest TC removal efficiency (99%). At this pH value, almost complete TC removal was achieved at a Fe₂O₃-scallop shell nanocomposite dose of 1.6 g L⁻¹ and 25°C. The responsible TC removal mechanism is suggested as the non-electrical π–π dispersion interaction between the bulk π system on the absorbent surface and TC molecules bearing both benzene rings and double bonds at this solution pH. TC removal efficiency appreciably enhanced up to the Fe₂O₃-scallop dosage of 1.6 g L⁻¹ being an optimum. Adsorption rate was found to be fast at lower initial TC concentrations than 40 mg L⁻¹. The effect of temperature on TC removal efficiency was insignificant. Adsorption followed the pseudo-second-order kinetic model. Experimental data perfectly fitted by the Langmuir equation. The maximum adsorption capacity was calculated as 49.26 mg g⁻¹. Thermodynamic analysis demonstrated that adsorption process was spontaneous process and endothermic. The results obtained from the present study proved the excellent performance of scallop shell coated Fe₂O₃ nanoparticles as an eco-friendly adsorbent in TC treatment.

摘要

本研究的重点是扇贝壳包覆的 Fe ₂ O ₃纳米粒子作为一种环保型新型吸收剂在四环素 (TC) 处理中的可用性。在不同操作条件下研究了 TC 去除的工艺性能，即溶液 pH 值为 3-11，Fe ₂ O ₃ -扇贝剂量为 0.4-2.4 g L ^-1，初始 TC 含量为 20-120 mg L ^{- 1}和 25–55°C 的温度。溶液 pH 值为 7 的 TC 去除效率最高 (99%)。^{在此 pH 值下，在 1.6 g L −1的 Fe} ₂ O ₃ -扇贝壳纳米复合材料剂量下实现了几乎完全的 TC 去除和 25°C。负责任的 TC 去除机制被认为是吸收表面上的本体π系统与在此溶液 pH 下同时带有苯环和双键的 TC 分子之间的非电π - π分散相互作用。TC 去除效率明显提高，直至1.6 g L ^{-1的 Fe} ₂ O ₃ -扇贝剂量为最佳。在低于 40 mg L ^{-1的初始 TC 浓度下发现吸附速率很快}. 温度对 TC 去除效率的影响不显着。吸附遵循伪二级动力学模型。实验数据完全符合朗缪尔方程。最大吸附容量计算为49.26 mg g ^-1。热力学分析表明吸附过程是自发的吸热过程。从本研究中获得的结果证明了扇贝壳包覆的 Fe ₂ O ₃纳米粒子作为生态友好型吸附剂在 TC 处理中的优异性能。