Hasany Syed Moosa, Ahmad Rashid
Nuclear Chemistry Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad, Pakistan.
J Environ Manage. 2006 Nov;81(3):286-95. doi: 10.1016/j.jenvman.2006.01.009. Epub 2006 May 19.
Coconut (Cocos nucifera) husk, an agricultural waste, has been thoroughly investigated for the removal of toxic Cd(II), Cr(III) and Hg(II) ions from aqueous media. The parameters like nature and composition of electrolyte, concentration of toxic ions, dosage of coconut husk, and equilibration time between the two phases were optimized for their maximum accumulation onto the solid surface. The effect of common ions on the uptake of metal ions has been monitored under optimal conditions. The variation of retention of each metal ion with temperature was used to compute the thermodynamic quantities DeltaH, DeltaS and DeltaG. The values 18.1+/-0.6 kJmol(-1), 74+/-2 Jmol(-1)K(-1), and -3.8+/-0.04 kJmol(-1) at 298 K; 10.8+/-0.8 kJmol(-1), 48.8+/-2.7 Jmol(-1)K(-1), and -4.6+/-0.3 kJmol(-1) at 298 K; and -37.4+/-2k Jmol(-1), 105+/-7 Jmol(-1)K(-1) and -2.58+/-0.5 kJmol(-1) at 298 K were obtained for Cd(II), Cr(III) and Hg(II) ions, respectively. The sorption data were analysed by applying different sorption isotherms. The sorption capacity and energy were evaluated for each metal ion. The values of the Freundlich constants 1/n and C(m) were 0.92+/-0.04 and 52.6+/-22.2 mmolg(-1); 0.85+/-0.05 and 56.0+/-0.03 mmolg(-1); and 0.88+/-0.03 and 6.84+/-0.45 mmolg(-1) for Cd(II) Cr(III) and Hg(II) ions, respectively. Similarly, the Dubinin-Radushkevich (D-R) constants beta, X(m,) and E were evaluated for the three metal ions. To check the selectivity of the sorbent, sorption of a number of elements was measured under similar conditions. Separation of Zn(II) from Cd(II); Cr(III) from I(I), Zr(IV), Se(IV), and Hg(II) from Se(IV) and Zn(II) can be achieved using this sorbent. This cheap material has potential applications in analytical chemistry, water decontamination, industrial effluent treatment and in pollution abatement.
椰子（椰属）外壳作为一种农业废弃物，已被深入研究用于从水介质中去除有毒的镉（II）、铬（III）和汞（II）离子。对诸如电解质的性质和组成、有毒离子浓度、椰子壳用量以及两相之间的平衡时间等参数进行了优化，以实现其在固体表面的最大积累。在最佳条件下监测了常见离子对金属离子吸收的影响。利用每种金属离子保留率随温度的变化来计算热力学量ΔH、ΔS和ΔG。在298K时，镉（II）、铬（III）和汞（II）离子的值分别为18.1±0.6kJmol⁻¹、74±2Jmol⁻¹K⁻¹和 - 3.8±0.04kJmol⁻¹；在298K时，分别为10.8±0.8kJmol⁻¹、48.8±2.7Jmol⁻¹K⁻¹和 - 4.6±0.3kJmol⁻¹；在298K时，分别为 - 37.4±2kJmol⁻¹、105±7Jmol⁻¹K⁻¹和 - 2.58±0.5kJmol⁻¹。通过应用不同的吸附等温线对吸附数据进行了分析。对每种金属离子的吸附容量和能量进行了评估。镉（II）、铬（III）和汞（II）离子的弗伦德利希常数1/n和C(m)的值分别为0.92±0.04和52.6±22.2mmol·g⁻¹；0.85±0.05和56.0±0.03mmol·g⁻¹；以及0.88±0.03和6.84±0.45mmol·g⁻¹。同样，对三种金属离子评估了杜比宁 - 拉杜什凯维奇（D - R）常数β、X(m)和E。为检验吸附剂的选择性，在相似条件下测量了多种元素的吸附情况。使用这种吸附剂可实现从镉（II）中分离锌（II）；从碘（I）、锆（IV）中分离铬（III），从硒（IV）和锌（II）中分离汞（II）。这种廉价材料在分析化学、水净化、工业废水处理及污染治理方面具有潜在应用价值。
