Adsorption Mechanism Of Cu（Ⅱ）in The Aqueous Solution By Attapulgite

With the rapid development of modern industries, the environment has faced more andmore contamination than in the past, and one of the major pollutants in the environment isheavy metal. Copper is a widespread contaminant. It arises from both natural andanthropogenic sources. Copper in the water causes serious harm on plants, animals, humanand ecological environment. Because of the convenient operation and economic application,adsorption is studied and used widely. As the emerging adsorption material, attapulgite haslarge reserves and low price, the adsorption performance of attapulgite is excellent. This paperused red attapulgite produced in Gansu Jingyuan for raw materials. After crushed, grinded,screened, purified and modified, attapulgite was produced for three kinds of samples. Thestatic adsorption experiments were done for investigating adsorption effects by different kindsof samples. The assay data were linear fitting for adsorption isotherm and adsorption kinetics,the thermodynamics parameters were also calculated. Under different adsorption conditions,different pretreatment attapulgite adsorption rates were analyzed by analysis of variance andmultiple comparisons.The results showed that:(1) the adsorption process of original attapulgite complies withthe Freundlich adsorption isotherm, the result shows that the adsorbent surface is uneven.0<R_L<1and0<1/n<1indicate that adsorption process is good and adsorption is easy. Pseudosecondary dynamics equation accords with the adsorption process of original attapulgite toCu(Ⅱ) in water. The process is mainly for chemical adsorption. The adsorption process oforiginal attapulgite to Cu(Ⅱ) in water is spontaneous, entropy increasing and endothermicprocess.(2) The adsorption process of purified attapulgite complies with the Langmuiradsorption isotherm; the result shows that the adsorbent surface is uniform.0<R_L<1and0<1/n<1indicate that adsorption process is good and adsorption is easy. The adsorptionprocess of original attapulgite to Cu(Ⅱ) in water accords with Pseudo secondary dynamicsequation, the process is mainly for chemical adsorption. The adsorption process isspontaneous, entropy increasing and endothermic process.(3) The adsorption process ofmodified attapulgite complies with the Langmuir adsorption isotherm; the result shows thatthe adsorbent surface is uniform.0<R_L<1and0<1/n<1indicate that adsorption process isgood and adsorption is easy. The adsorption process of original attapulgite to Cu(Ⅱ) in wateraccords with Pseudo secondary dynamics equation, the process is mainly for chemicaladsorption. The adsorption process is spontaneous, entropy increasing and endothermicprocess.(4) By the same initial concentration, the adsorption rates of original attapulgite areno significant differences under different adsorption time. The adsorption rate differences ofpurified attapulgite and modified attapulgite are more significant with the increase ofadsorption time. The different pretreatment attapulgite adsorption rates show a trend ofincrease with the increase of adsorption time, and the adsorption rates are significant differences. The adsorption rates of purified attapulgite are higher than the adsorption rates ofmodified attapulgite; both are significantly higher than the adsorption rates of originalattapulgite. The different pretreatment attapulgite adsorption rates are significantly differencesby the increase of initial concentration, the values of adsorption rates gradually decreases. Fordifferent initial concentrations of Cu(Ⅱ), the adsorption equilibrium time of differentpretreatment attapulgite gradually increase by the increase of initial concentration.