The Interactions Of Humic Acid With Zn～(2+), Ni～(2+) And Co-existed Zn～(2+), Cd～(2+) And The Affecting Factors

Humic acids , the most widely distributed natural organic matter in the biological environment. Owing to their great variety of functional groups, they have great activation in reaction with metal ions,and they have greatly significant meaning to environment,So much research on this field had been done in recent 20 years.But the research before has many shortcomings.Bcause of the lack of good veracity ion selective electrodes, there have been rare report about Zn? Ni ions research recently.Further more previous research seldom considers the redox activity of humus and some possess redox activity metals.Thus, despite the methods of study is very complicated, it is necessary for the study on mechanism of humus acids and Zn2+, Ni2+.It has important meaning on illuminating commonly rule of humic acids and metal ions, developping and updating science knowledge on this field, accmodating and cortrolling the transferring, transforming and toxicity of metal ions.This experiment focuses on the mechanism and characteristics of the interaction of HA with nichel and zinc ions, so as to reveal the mechanism of combination, adsorption characteristic, stability and affecting factors of the interaction, and provide theoretical basis for adjusting the metal ions activity in the environment and avoiding the environmental pollution.Humic acid (HA) and fulvic acid were extracted evergreen broad leaf forest surface layer soil of Jingyun Mountain in China. The contents of functional groups and the basic components of humic acids are measured by the methods that Qixiao Wen recommended in "Study methods of soil organic matter".The resoult showed that the contents of total acidity , carboxy and phenolic groups in the HA are less than that of FA. The contents of metal ions of humic acids are very low, this showed that the humic acids distilled by this methods is up to the mustard.The characteristic of humic acid adsorb and desorption Zn2+ ion and Ni2+ ion at different acidity, ion strength and temperature were studied, first use sulphopropyl Sephadex C-25 chromatography method.The results showed that if other conditions are not changed, the relationship between pH humic acids concentration and affiliated metal ions concentration and adsorption quantities of humic acids with the two metal ions is followed the same rule, namely the adsorption quantities increased with pH and affiliated metal ions concentration increased; the adsorption quantities decreased with humic acids concentration increased.The relationship between acidity and adsorption of HA-Ni2+ followed logarithm equation, and with the affiliated metal ions concentration increased, the slope also increased.But the relationship between acidity and adsorption of HA-Zn2+ obeyed linear equation at lower affiliated metal ions concentration , and obeyed logarithm equation at higher affiliated metal ions concentration.According to the equation when Nickel ions completeddesorbed the pH was between 2.3-2.6, while Zinc pH was 1.9~2.5.So the desorption of HA-Zn2+ was more difficulty than HA-Ni2+.The relationship between adsorption coefficient and pH, humic acids concentration and metal ions concentration was:when the pH and humic acids concentration increased, adsorption coefficient increased, while the affiliated metal ions concentration increased, adsorption coefficient decreased.On the condition of [HA] isl.04g/L> ionic strength is 0.10mol/L, temperature is 298K, after using several equation to simulate conclusion has been drawn as follows: When pH of the solution was 3.0 the adsorption of Ni2+and Zn2+ by HA could be best described by Linear and Fruendlich equation(r=0.9822~0.9971).when pH of the solution was in the range of 4.0-8.0, adsorption of nickel and znic by HA could be best described by Langmiure equation(r=0.9902~0.9988).The max adsorption Smax and adsorption equilibrium constants k increased with the increased pH. The max adsorption S^ of humic acid with Ni2+was in the range of 0.37~-0.69mmol/gHA, while the Smax of humic acid with Zn2+ was in the range of 0.77~0.82mmol/gHA. rGm<0, and decreased with pH increase. logK of HA- Ni2+ with pH can descrided by logarithm equation, while logAT of HA- Zn2+ with pH can descrided by linear equation. On the condition of [HA] is0.52g/L-. ionic strength is 0.10mol/L temperature is 298K using several equation to simulate conclusion has been drawn followed the same rule. But in the range of 4.0-7.0, the Smax of humic acid with Zn2+was in the range of 1.31 ~ 1.95mmol/gHA, logK of HA- Zn2+ with pH can descrided by exponent equation.The adsorption quantities of HA-Ni2+ decreased with temperature and ionic strength increased, logAT and increased with temperature decreased, This showed that lower temperature is more available to the adsorptionc reaction of HA-Ni~2 and were all lower than zero, This showed that the adsorption of humic acids and Ni2+ is spontaneous and radiative.And from the datd of can be detected that the machenism of HA-Ni2+ is mainly involved coordination change and dipole bond forces.The max adsorption Smax of humic acid with Ni2+ decreased with temperature, humic acids concentration and ionic strength increased , adsorption equilibrium constants k increased with humic acids concentration increased, but decreased with temperature increased, and firstly increased with ion strength increased, but later decreased.From the reaction can detect that HA-Ni2+ has not "two-phase" character, while the reaction can detect that HA-Zn2+ has "two-phase" character.The stability and thermodynamic character of humic acid coordinate Zn2+ion and Ni2+ ion at different acidity, ion strength and temperature were studied, used ion-exchange equilibrium method.The result indicated that stability constant logK and coordination number x all increased with...