Fotsing P Nkuigue, Woumfo E Djoufac, Mezghich S, Mignot M, Mofaddel N, Le Derf F, Vieillard J
Laboratory of Applied Inorganic Chemistry, Faculty of Sciences, University of Yaoundé I P.O. Box 812 Yaoundé Cameroon
Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014) 55, rue Saint Germain, 27000 Evreux France.
RSC Adv. 2020 May 27;10(34):20009-20019. doi: 10.1039/d0ra03027a. eCollection 2020 May 26.
The present work addresses the development of simple, low-cost and eco-friendly cocoa-shell-based materials for efficient removal of heavy metal hexavalent chromium (Cr(vi)), and toxic nitrate (NO ) from aqueous solution. A conventional treatment process was used to purify cocoa shell (CS) into an adsorbent, followed by chemical grafting of dendrimers to promote its surface properties for nitrate and Cr(vi) removal. The morphology, surface charge, structure and stability of the new adsorbent were investigated by scanning electron microscopy, Fourier transform infrared and UV-visible spectroscopies, zeta potential, X-ray photoelectron spectrometry, and differential scanning calorimetry. The successful chemical grafting of the dendrimer (polyethyleneimine, PEI) onto purified CS was confirmed. CS-T-PEI-P proved to be a very efficient candidate for the removal of nitrate and chromium(vi). Removal of the two pollutants at different initial concentrations and pH values was studied and discussed. Sorption of chromium and nitrate was found to obey 2-order kinetics and a Freundlich-type isotherm, affording an uptake adsorption of 16.92 mg g for NO and 24.78 mg g for Cr(vi). These results open promising prospects for its potential applications as a low cost catalyst in wastewater treatment.
本研究致力于开发简单、低成本且环保的可可壳基材料，用于从水溶液中高效去除重金属六价铬（Cr(VI)）和有毒硝酸盐（NO₃⁻）。采用传统处理工艺将可可壳（CS）提纯为吸附剂，随后通过树枝状聚合物的化学接枝来改善其表面性质，以实现对硝酸盐和Cr(VI)的去除。通过扫描电子显微镜、傅里叶变换红外光谱和紫外可见光谱、zeta电位、X射线光电子能谱以及差示扫描量热法对新型吸附剂的形态、表面电荷、结构和稳定性进行了研究。证实了树枝状聚合物（聚乙烯亚胺，PEI）成功化学接枝到提纯的CS上。CS-T-PEI-P被证明是去除硝酸盐和六价铬的高效候选材料。研究并讨论了在不同初始浓度和pH值下两种污染物的去除情况。发现铬和硝酸盐的吸附符合二级动力学和Freundlich型等温线，对NO₃⁻的吸附量为16.92 mg g⁻¹，对Cr(VI)的吸附量为24.78 mg g⁻¹。这些结果为其作为低成本催化剂在废水处理中的潜在应用开辟了广阔前景。
