Department of Chemistry, Presidency College, 86/1 College Street, Kolkata 700073, India.
Polymers and composites, Materials Science and Manufacturing (MSM), Council for Scientific and Industrial Research (CSIR), 1-Meiring Road, Brummenia, Pretoria 0001, South Africa.
J Hazard Mater. 2010 Dec 15;184(1-3):832-842. doi: 10.1016/j.jhazmat.2010.08.117. Epub 2010 Sep 6.
Three samples of manganese associated hydrous iron(III) oxide (MNHFO), prepared by incinerating metal hydroxide precipitate at T (± 5)=90, 300 and 600°C, showed increase of crystalline nature in XRD patterns with decreasing As(III) removal percentages. TEM images showed the increase of crystallinity from sample-1 (MNHFO-1) to sample-3 (MNHFO-3). Dimensions (nm) of particles estimated were 5.0, 7.0 and 97.5. Optimization of pH indicated that MNHFO-1 could remove aqueous As(III) efficiently at pH between 3.0 and 7.0. Kinetic and equilibrium data of reactions under the experimental conditions described the pseudo-second order and the Langmuir isotherm equations very well, respectively. The Langmuir capacity (q(m)) estimated was 691.04 mmol kg(-1). The values of enthalpy, Gibb's free energy and entropy changes (ΔH(0)=+23.23 kJ mol(-1), ΔG(0)=-3.43 to -7.20 kJ mol(-1) at T=283-323K, ΔS(0)=+0.094 kJ mol(-1)K(-1)) suggested that the reaction was endothermic, spontaneous and took place with increasing entropy. The As(III) sorbed by MNHFO-1 underwent surface oxidation to As(V), and evidences appeared from the XPS and FTIR investigations. MNHFO-1 packed column (internal diameter: 1.0 cm, height: 3.7 cm) filtered 11.5 dm(3) groundwater (105 μg As dm(-3)) with reducing arsenic concentration to ≤ 10 μg dm(-3).
三种锰结合水合氧化铁（MNHFO）样品，通过在 T（±5）=90、300 和 600°C 下煅烧金属氢氧化物沉淀物制得，随着 As(III)去除率的降低，XRD 图谱中显示出结晶度的增加。TEM 图像显示，从样品 1（MNHFO-1）到样品 3（MNHFO-3），结晶度增加。估计的颗粒尺寸（nm）分别为 5.0、7.0 和 97.5。pH 值的优化表明，MNHFO-1 可以在 pH 值为 3.0 至 7.0 之间有效去除水溶液中的 As(III)。在描述的实验条件下的反应动力学和平衡数据很好地描述了准二级和 Langmuir 等温线方程。估计的 Langmuir 容量（q(m)）为 691.04 mmol kg(-1)。焓、Gibbs 自由能和熵变化的数值（ΔH(0)=+23.23 kJ mol(-1)，ΔG(0)=-3.43 至-7.20 kJ mol(-1)，T=283-323K，ΔS(0)=+0.094 kJ mol(-1)K(-1)）表明该反应是吸热的、自发的，并且伴随着熵的增加。MNHFO-1 吸附的 As(III)经历了表面氧化为 As(V)，从 XPS 和 FTIR 研究中可以得到证据。MNHFO-1 填充柱（内径：1.0 cm，高度：3.7 cm）过滤了 11.5 dm(3)地下水（105 μg As dm(-3))，将砷浓度降低至≤10 μg dm(-3)。
