| Due to its excellent thermal and chemical stability, polyaniline (PANI) becomes one of most classical macromolecules nowadays. PANI molecule contains a large number of -NH2 and-NH, which has a good heavy metal ions complexation. And these -NH2 and -NH also has a reductive, with some of the higher oxidation potential ofredox reactions of heavy metal ions adsorption, while polyaniline class of adsorbent Pb2+, Hg2+ and other heavy metal ions with the ion exchange capabilities, and the PANI with good solvent resistance, so that it can be widely adapted to a variety of complex adsorption environment.Attapulgite(ATP) is a silicate clay mineral with high specific surface, excellent absorbability and better decoloring capacity. Thus, it has been widely used in industry.Using attapulgite as carrier, it performs that the surface of attapulgite is covered with the mixture of hydrochloric acid and polyaniline. Then PANI / ATP nanocomposites are produced by the method of in-situ polymerization. It shows the structure of composite material and discusses the formation mechanism and absorbability of composite material. The main results of this research are as follows:(1) Silicate attapulgite/polyaniline nanocomposites with excellent properties and low cost were first prepared from a direct in situ polymerization. The chemical structures, morphologies characters, crystallographic forms and thermal stabilities of the nanocomposites were analysized and discussed in detail, which owned good conductivity.(2) The structure and absorption mechanism for eriochrome blue black of Polyaniline/attapulgite nanocomposites were investigated. Amount of absorbent and influence of pH for absorbent effect were also studied. The results reveal that the nanocomposites have not only the structure of ATP but also the property of the PANI. The nanocomposites hold an excellent adsorption for eriochrome blue black when the pH value is 5. The adsorption thermodynamics of the nanocomposites follows the Langmuir isothermal adsorption equation. The maximum adsorption capacity can reach 192.67mg/g. The calculate results show that the adsorption enthalpy is 4.15kJ/mol, the Gibbs free energy is (–22.98 to–19.26) kJ/mol, and the entropy of 81J/(mol·K), which imply that the adsorption is an endothermal and spontaneous process. (3) Polyaniline/attapulgite nanocomposites is used for the research on the adsorption of the effluent with the trace of Cr(Ⅵ). It makes a study of the influence by the ratio of the materials, the quality of the composite materials, adsorptive time, adsorptive temperature and pH value on the adsorptive property of composite materials. The result turns out that when the ratio of the materials is 2:1, the quality is 0.4g, the time is 50min that the effect of Cr(Ⅵ) is 99% by the composite materials. this process of adsorption adjusts to Langmuir adsorption isotherm.(4) A experiment was conducted to study the two component solution Cr (VI), Cu (II) adsorption of wastewater on Polyaniline/attapulgite nanocomposites. The impact of Cr (VI), Cu (II) adsorption rate of the main factors, the thermodynamic properties. and two adsorption isotherm type, by desorption of the composite materials on the dual ion adsorption mechanism were examined, as well as composite materials on the two-component mechanism obtained by desorption to the adsorption. The results show that: composite materials on the adsorption of two different mechanisms are the main reasons leading to the adsorption rate of two different trends.
|
PDF Full Text Request