CAJ | 학술논문

用自行设计的动力学装置研究了酸性条件下Zn在红壤表面的反应动力学能量特征.结果表明,酸性条件下,Zn吸附分为快反应和慢反应.用一级动力学方程拟合的Zn最大吸附量:pH5.5处理Zn的最大吸附量在289 K时为1.79 mmol·kg~(-1),在313 K时为2.62 mmol·kg~(-1);pH3.3处理Zn的最大吸附量在289 K时为0.12 mmol·kg~(-1),在313 K时为0.16 mmol·kg~(-1).即吸附量随酸度增加显著下降,随温度升高明显增加.用扩散速率常数计算的活化能(△E~*):pH5.5处理Zn的△E~*为9.05 kJ·mol~(-1),pH3.3处理Zn的△E~*为12.02 kJ·mol~(-1),随酸度的增加△E*增加,Zn扩散需克服的能障加大,Zn吸附量降低.△H值为正,温度升高可促进Zn的扩散;△S值均为负,说明吸附反应使体系有序度增加.原液pH为5.5时,流出液的pH急剧下降;pH4.3、pH3.8和pH3.3时流出液比流入液的pH高,是由于土壤的缓冲作用和土壤表面质子化;当溶液中H~+超过一定数量后,反应初期的H~+消耗是快反应过程,H~+对矿物的溶蚀成为速率控制步骤.
용자행설계적동역학장치연구료산성조건하Zn재홍양표면적반응동역학능량특정.결과표명,산성조건하,Zn흡부분위쾌반응화만반응.용일급동역학방정의합적Zn최대흡부량:pH5.5처리Zn적최대흡부량재289 K시위1.79 mmol·kg~(-1),재313 K시위2.62 mmol·kg~(-1);pH3.3처리Zn적최대흡부량재289 K시위0.12 mmol·kg~(-1),재313 K시위0.16 mmol·kg~(-1).즉흡부량수산도증가현저하강,수온도승고명현증가.용확산속솔상수계산적활화능(△E~*):pH5.5처리Zn적△E~*위9.05 kJ·mol~(-1),pH3.3처리Zn적△E~*위12.02 kJ·mol~(-1),수산도적증가△E*증가,Zn확산수극복적능장가대,Zn흡부량강저.△H치위정,온도승고가촉진Zn적확산;△S치균위부,설명흡부반응사체계유서도증가.원액pH위5.5시,류출액적pH급극하강;pH4.3、pH3.8화pH3.3시류출액비류입액적pH고,시유우토양적완충작용화토양표면질자화;당용액중H~+초과일정수량후,반응초기적H~+소모시쾌반응과정,H~+대광물적용식성위속솔공제보취.
Energy characteristics of the reaction kinetics of Zn on red soil surface under acidic conditions were investigated by using a home made dynamic device. The results showed that Zn adsorption could be divided into rapid and slow reactions. The maximum amount of Zn adsorption fitted by the first order equation was 1.79 and 2.62 mmol·kg~(-1) at 289 K and 313 K in pH5.5 treatment, and 0.12 and 0.16 mmol·kg~(-1) at 289 K and 313 K in pH3.3 treatment, respectively. It remarkably decreased with increase in acidity and increased with increase in temperature. Activation energy (△E~* )of Zn diffusion calculated by using b value of the rate constant of parabolic diffusion law was 9.05 and 12.02 kJ·mol~(-1) in pH5.5 and pH3.3 treatments, respectively. It increased with increase in acidity, which reflected that the energy barrier to be overcome by Zn diffusion would rise up and the rate of diffusion in Zn adsorption decrease accordingly. Enthalpy of activation (△H )was positive in value and rising temperature could contribute to Zn diffusion. Entropy of activation (△S )was negative in all cases, suggesting that system could improve its degree of order. The effluent pH drastically dropped when the influent solution was pH5.6. There was the consumption process of H~+ by using influent of pH4.3 and pH3.8 and pH3.3, which was attributed to soil buffer mechanism. H~+ consumption was rapid at the initial stage of the reaction. Since H~+ dissolution of minerals became a controlling process.