Osobamiro T M, Ademuyiwa E T, Ajibade O M, Hashimi A S
Department of Chemical Sciences, Olabisi Onabanjo University, P. M. B. 2002, Ago-Iwoye, Nigeria.
J Toxicol. 2020 Sep 12;2020:4421117. doi: 10.1155/2020/4421117. eCollection 2020.
Geophagy clay has been used in tropical regions as gastrointestinal protector for adsorbing toxins in human body, but it was rarely used in adsorbing heavy metals contaminants in water. This study determines elemental concentration of geophagy clay and evaluates its adsorptive capacity in removing Cd and Pb in water. Fifteen clay samples were randomly collected from three layers in the space of one meter apart from Amawom clay deposit in Ikwuano local government, Southeast Nigeria. Elemental analysis was carried out using the inductively coupled plasma mass spectrophotometer (ICP-MS), and chemical characterization was performed with Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). The adsorptive capacity of Cd and Pb on the clay samples was evaluated using standard solutions of the metal ions. The result of the elemental analysis in mg/kg (Pb ≤ 12.4, Zn ≤ 2.75, Co ≤ 1.50, Ni ≤ 1.47, Mn ≤ 15.0, Cd = 0.01, Ca ≤ 300, Al ≤ 3466, Na ≤ 13.3, and Hg = 0.02; ≤ 40.0) revealed that the concentrations of most of the studied metals in the three layers are statistically similar and fall below the permissible recommended safety levels. The presence of functional groups (hydroxyl, amine, and carboxylic/ester) and minerals (kaolinite, goethite, and quartz) provided evidence of the good adsorptive properties of the clay samples. The adsorption of Cd and Pb unto the clay samples increased with increase in pH, concentration, time, and temperature, and the equilibrium data for the adsorption fitted well into Langmuir isotherm. The study, therefore, concluded that geophagy clay possesses the capacity to adsorb Cd and Pb for water treatment.
食土性黏土在热带地区一直被用作胃肠道保护剂，用于吸附人体中的毒素，但很少用于吸附水中的重金属污染物。本研究测定了食土性黏土的元素浓度，并评估了其去除水中镉和铅的吸附能力。从尼日利亚东南部伊夸诺地方政府阿马沃姆黏土矿床中相距1米的三个层位随机采集了15个黏土样本。使用电感耦合等离子体质谱仪（ICP-MS）进行元素分析，并用傅里叶变换红外光谱仪（FT-IR）和X射线衍射仪（XRD）进行化学表征。使用金属离子标准溶液评估黏土样本对镉和铅的吸附能力。元素分析结果（单位为mg/kg，铅≤12.4，锌≤2.75，钴≤1.50，镍≤1.47，锰≤15.0，镉 = 0.01，钙≤300，铝≤3466，钠≤13.3，汞 = 0.02；≤40.0）表明，三层中大多数研究金属的浓度在统计学上相似，且低于允许的推荐安全水平。官能团（羟基、胺基和羧基/酯基）和矿物质（高岭石、针铁矿和石英）的存在证明了黏土样本具有良好的吸附性能。黏土样本对镉和铅的吸附随着pH值、浓度、时间和温度的升高而增加，吸附平衡数据很好地符合朗缪尔等温线。因此，该研究得出结论，食土性黏土具有吸附镉和铅用于水处理的能力。
