Department of Chemistry, Koneru Lakshmaiah Education Foundation, Green Fields, Vaddeswaram-522 502, Guntur Dt., A.P., India E-mail:
Water Sci Technol. 2020 Jun;81(12):2617-2633. doi: 10.2166/wst.2020.318.
Nano particles of ZrO of average size 10.91 nm are successfully synthesized via green routes from a solvent blend of water and ethylene glycol (4:1 v/v). Bio-extract of seeds of Sapindus plant is employed as stabilizing and/or capping agent and homogeneous method of precipitation is adopted to generate the precipitating agent. The nZrO particles are immobilized in aluminum alginate beads (nZrO-Al- alig). Nano-ZrO and beads are investigated as adsorbents for the extraction of phosphate from water. The controlling physicochemical parameters are studied for the maximum phosphate removal using simulate water. The optimum conditions are: pH: 7; sorbent dosage: 0.1 g/100 mL for nZrO and 0.08 g/100 mL for beads; equilibration time: 30 min.for nZrO and 35 min for beads; initial phosphate concentration: 50 mg/L; temperature: 30 ± 1 °C; 300 rpm. The adsorption capacities are: 126.2 mg/g for nZrO and 173.0 mg/g for 'nZrO-Al- alig' and they are higher than many reported in literature. The beads, besides facilitating the easy filtration, are exhibiting enhanced cumulative phosphate-adsorption nature of nanoZrO and Al-alginate. X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) investigations are employed in characterizing the adsorbents. Of the various isotherm models analyzed to assess the nature of adsorption, Freundlich model provides the best correlation (R = 0.99 for nZrO and R = 0.99 for 'nZrO-Al-alig'), indicating the heterogeneous and multi-layered adsorption process. Thermodynamic studies reveal the endothermic and spontaneous nature of sorption. Pseudo-second-order model of kinetics describes the adsorption well. Spent adsorbents can be regenerated with marginal loss of adsorption capacity until five cycles. The sorbents are successfully applied to remove phosphate from polluted lake water samples.
成功地通过水和乙二醇（4:1v/v）溶剂混合物的绿色途径合成了平均粒径为 10.91nm 的 ZrO 纳米粒子。Sapindus 植物种子的生物提取物用作稳定剂和/或封端剂，并采用均相沉淀法生成沉淀剂。将 nZrO 颗粒固定在海藻酸钠珠粒（nZrO-Al-alig）中。纳米-ZrO 和珠粒被用作从水中提取磷酸盐的吸附剂。研究了控制物理化学参数，以使用模拟水实现最大磷酸盐去除率。最佳条件为：pH：7；吸附剂用量：nZrO 为 0.1g/100mL，珠粒为 0.08g/100mL；平衡时间：nZrO 为 30min，珠粒为 35min；初始磷酸盐浓度：50mg/L；温度：30±1°C；300rpm。吸附容量为：nZrO 为 126.2mg/g，nZrO-Al-alig 为 173.0mg/g，均高于文献报道的许多值。珠粒除了便于过滤外，还表现出增强的纳米 ZrO 和海藻酸钠的累积磷酸盐吸附特性。X 射线衍射（XRD）、傅里叶变换红外（FTIR）、场发射扫描电子显微镜（FESEM）和能谱（EDX）分析用于表征吸附剂。在所分析的各种等温模型中，Freundlich 模型提供了最佳相关性（nZrO 为 0.99，nZrO-Al-alig 为 0.99），表明吸附过程为非均相和多层吸附。热力学研究表明吸附是吸热和自发的。动力学的拟二级模型很好地描述了吸附过程。用过的吸附剂可以再生，再生后吸附容量略有损失，直到五个循环。这些吸附剂成功地应用于去除受污染湖水样品中的磷酸盐。
