This study combined agricultural waste utilization with wastewater treatment and developed a novel nanocomposite adsorbent for Cu${}^{2+}$ removal from water. Rice straw (RS) was used as the supporter of hydrated titanium oxide (HTO), which has strong affinity toward heavy metals. HTO nanoparticles were uniformly loaded onto the surface of natural rice straw through a facile sol–gel method. The characterization results show that the diameter of the RS-HTO nanoparticles was about 80 nm with SEM. The fabricated nanocomposite RS-HTO exhibited excellent structural stability under different solution pH and ionic strength. Adsorption of Cu${}^{2+}$ increased as pH rose from 2.0 to 7.5 with 2 g/L RS-HTO in 50 mL solution (10 mg/L). Meanwhile, when initial concentration of Cu${}^{2+}$ was 10 mg/L, the adsorptive removal efficiency was higher than 99% by RS-HTO at a pH level of 7.5. The adsorption selectivity was investigated and proved that the coexisting cation ions such as Na${}^{+}$, Mg${}^{2+}$ and Ca^2＋ led to a small decrease of Cu${}^{2+}$ adsorption capacity. Adsorption isotherms of Cu${}^{2+}$ onto RS-HTO fitted well with Langmuir equation, and the adsorption kinetics were best described by pseudo-second order model. The concentration of Cu${}^{2+}$ in the simulated wastewater can be reduced to be lower than 0.2 mg/L through fixed-bed adsorption process and the exhausted RS-HTO can be easily regenerated with HCl–NaCl mixed solution.

该研究将农业废物利用与废水处理相结合，并开发了一种新型的铜纳米复合吸附剂。${}^{2+}$从水中去除。稻草（RS）用作水合氧化钛（HTO）的载体，它对重金属具有很强的亲和力。通过简便的溶胶-凝胶法将HTO纳米颗粒均匀地加载到天然稻草的表面上。表征结果表明，RS-HTO纳米颗粒的直径用SEM观察为约80nm。所制备的纳米复合材料RS-HTO在不同溶液pH和离子强度下均表现出优异的结构稳定性。铜的吸附${}^{2+}$当在50 mL溶液（10 mg / L）中使用2 g / L RS-HTO将pH从2.0升高至7.5时，pH升高。同时，当铜的初始浓度${}^{2+}$浓度为7.5 mg / L时，RS-HTO的吸附去除率高于99％。研究了其吸附选择性并证明了共存的阳离子如Na${}^{+}$镁${}^{2+}$和Ca ^2＋导致Cu的少量减少${}^{2+}$吸附能力。Cu的吸附等温线${}^{2+}$用Langmuir方程很好地拟合了RS-HTO，并用伪二级模型最好地描述了吸附动力学。铜的浓度${}^{2+}$ 通过固定床吸附工艺，可将模拟废水中的三氧化二砷降低至低于0.2 mg / L，并且用HCl-NaCl混合溶液可轻松再生用尽的RS-HTO。