Ezeokonkwo Mercy A, Ofor Okechukwu F, Ani Julius U
Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Nigeria.
Front Chem. 2018 Jan 26;5:132. doi: 10.3389/fchem.2017.00132. eCollection 2017.
Cd(II) and Pb(II) ions removal using adsorbents prepared from sub-bituminous coal, lignite, and a blend of coal and seed shells was investigated. Fourier transform infrared, scanning electron microscope and X-ray fluorescence analyses implicated hydroxyl, carbonyl, AlO, and SiO as being responsible for attaching the metal ions on the porous adsorbents. The optimum adsorption of carbonized lignite for the uptake of Cd(II) and Pb(II) ions from aqueous media were 80.93 and 87.85%, respectively. Batch adsorption was done by effect of adsorbent dosage, pH, contact time, temperature, particle size, and initial concentration. Equilibrium for the removal of Pb(II) and Cd(II) was established within 100 and 120 min respectively. Blending the lignite-derived adsorbent with seed shell improved the performance significantly. More improvement was observed on modification of the blend using NaOH and HPO. Pb(II) was preferentially adsorbed than Cd(II) in all cases. Adsorption of Cd(II) and Pb(II) ions followed Langmuir isotherm. The adsorption kinetics was best described by pseudo-second order model. The potential for using a blend of coal and agricultural byproduct ( seed shell) was found a viable alternative for removal of toxic heavy metals from aqueous solutions.
研究了使用由次烟煤、褐煤以及煤与种壳混合物制备的吸附剂去除镉（II）和铅（II）离子的情况。傅里叶变换红外光谱、扫描电子显微镜和X射线荧光分析表明，羟基、羰基、AlO和SiO是金属离子附着在多孔吸附剂上的原因。碳化褐煤从水介质中吸附镉（II）和铅（II）离子的最佳吸附率分别为80.93%和87.85%。通过吸附剂用量、pH值、接触时间、温度、粒径和初始浓度的影响进行了批量吸附。去除铅（II）和镉（II）的平衡分别在100分钟和120分钟内建立。将褐煤衍生的吸附剂与种壳混合显著提高了性能。使用氢氧化钠和磷酸对混合物进行改性时观察到了更大的改善。在所有情况下，铅（II）比镉（II）更优先被吸附。镉（II）和铅（II）离子的吸附遵循朗缪尔等温线。吸附动力学用伪二级模型描述最佳。发现使用煤与农业副产品（种壳）的混合物是从水溶液中去除有毒重金属的可行替代方法。
