Department of Science Education, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra State, Nigeria.
Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria.
Sci Rep. 2022 Jul 1;12(1):11169. doi: 10.1038/s41598-022-15292-6.
The work reported herein explores the viability of cow dung ash (CDA) as a matrix for controlled pesticide delivery, by comparing its adsorptive characteristics towards two organophosphorus pesticides with those of starch, conventionally utilized in designing controlled pesticide delivery systems. CDA was characterized by Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD). Data for pesticide adsorption on the surfaces correlate well with Langmuir and Freundlich isotherms, with the former isotherm giving a slightly better fit (R ≥ 0.90) than the latter (R ≥ 0.81). Values of the adsorption parameters K and R indicate favourable pesticide adsorption on both surfaces. Desorption is the microscopic reverse of adsorption; both processes obey pseudo-second-order kinetics. The implication of this kinetic form is a mechanism in which adsorbate diffusion to the polymer surface and its transport into the polymer interior are important events. The isothermal and kinetic ratios, [Formula: see text] and 4.0, [Formula: see text] and 0.6, and [Formula: see text] and 1.0 at pH 7.0 and 27 °C, compare the adsorptive behaviour of diazinon and dichlorvos, respectively, on CDA and starch. These parameters are of the same order of magnitude, signalling that CDA is as potentially viable as starch for use as a matrix for pesticide-controlled delivery.
本文研究了牛粪灰（CDA）作为控制农药释放基质的可行性，通过比较其对两种有机磷农药的吸附特性与传统设计控制农药释放系统中使用的淀粉的吸附特性。用傅里叶变换红外（FTIR）光谱和粉末 X 射线衍射（PXRD）对 CDA 进行了表征。农药在表面上的吸附数据与 Langmuir 和 Freundlich 等温线很好地相关，前者比后者（R≥0.81）更能拟合（R≥0.90）。吸附参数 K 和 R 的值表明两种表面都有利于农药的吸附。解吸是吸附的微观逆过程；这两个过程都遵循拟二级动力学。这种动力学形式的含义是一种吸附剂扩散到聚合物表面及其进入聚合物内部的运输是重要事件的机制。在 pH 7.0 和 27°C 时，等温比和动力学比分别为[公式：见文本]和 4.0，[公式：见文本]和 0.6，[公式：见文本]和 1.0，比较了二嗪农和敌敌畏在 CDA 和淀粉上的吸附行为。这些参数具有相同的数量级，表明 CDA 作为控制农药释放的基质与淀粉一样具有潜在的可行性。
