【摘要】 研究了酸性条件下H+-Cu2+在红壤表面反应动力学的能量特征,结果表明:酸性条件下Cu2+的吸附分为快反应和慢反应两个阶段.用一级动力学方程拟合,Cu2+的最大吸附量随酸度的增加而显著下降,随温度的升高提前达到平衡.用双常数方程描述Cu2+在吸附点位能量分布的不均匀性,用扩散速率常数b计算,活化能(Eb*)随酸度的增加而增加,Cu2+扩散需要克服的能障变大;ΔH*值为正,温度升高可促进Cu2+的扩散;ΔS*均为负值,表明吸附反应使体系的有序度增加.原液pH值为3.8和3.3时,流出液的pH值高于原液,这是由于土壤的缓冲作用、土壤表面质子化和硫酸根专性吸附释放的羟基中和;反应初期H+消耗是快反应过程,反应后期H+对矿物的溶蚀为速率控制步骤.更多还原

【Abstract】 Energy characteristics of the reaction kinetics of H⁺- Cu²⁺on red soil surface under acidic condition were investigated by using a home-made dynamic device.The results showed that Cu²⁺adsorption could be divided into rapid and slow reactions.The maximal amount of Cu²⁺adsorption fitted by the first order equation remarkably（decreased） with increasing acidity and reached equilibrium earlier at higher temperature.A two-constant（equation） could be used to describe unevenness of the energy distribution of Cu²⁺ adsorption on soil surface.Activation energy（ΔE_b*） of Cu²⁺diffusion was calculated by using b value of the rate constant（b value）of parabolic diffusion equation and increased with increasing in acidity,which reflected that the energy barrier to be overcome by Cu²⁺diffusion would rise up and the diffusion rate in Cu²⁺adsorption decrease（accordingly）.Enthalpy（ΔH*） was positive in value and rising temperature could enhance Cu²⁺diffusion.Entropy（ΔS*）was negative in all cases,suggesting that system could improve its degree of order.There was the consumption process of H⁺ion on soil surface by using influent of pH3.3 and pH3.8,which was attributed to soil buffer mechanism and specific adsorption of SO₄^2-.H⁺consumption was rapid at the initial stage of the reaction,then the slow dissolution of minerals caused by H⁺ became a controlling process.更多还原