Adsorption Properties Of Cationic Dyse On PVFM Foam

Poly(vinyl formal) foam has a wealth of open-cell structure and excellent chemical resistance, the dry state of it is a kind of rigid foam which has high impact strength and compression modulus of elasticity. It was usually used in cosmetics powder brush, and the washing supplies of car. shower, photographic film and food containers, but also in print, medical and filtration materials. Meanwhile it is a interlayer of laminated plastic that is widely used in the aviation industry. In recent years, It is also as a filling material for waste treatment and modified, in order to get a good result.However, the research of adsorptions of PVFM foam is rarely.In this paper, PVFM was made of polyvinyl alcohol and formaldehyde firstly. This experiment studied the adsorption behaviors of cationic dye which included methylene blue and basic fuchsin on PVFM foam. The effects of dosage of PVFM foam, PH, adsorption time, initial concentration of methylene blue and temperature were investigated, in order to the optimal adsorption conditions. Meanwhile, the dynamics and thermodynamics of two kinds of dyes adsorpted on PVFM were studied.Through the adsorbent dosage, solution PH value, adsorption'time, initial dye concentration and temperature on the adsorption rate, it was founded that the removal rate of two kinds of dyes adsorped on PVFM increased with the increase in the amount of adsorbent, but adsorption capacity reduced, the best adsorption capacity of Methylene blue and basic fuchsin were respectively 2.0 and 1.6g, the adsorption rate remained at about 93 and 97% respectively, the adsorbing capacity remained at about 0.40 and 0.48mg/g respectively. When the solution PH≥4.0, adsorbing capacity of methylene blue remained at about 0.46mg/g, the basic fuchsin adsorbing capacity remained at about 0.60mg/g, in the PH of 4-10. After 200min in the adsorption time, adsorption of methylene blue and basic fuchsin on PVFM foam reached saturation basically. The methylene blue adsorption on PVFM foam is exothermic process, but the basic fuchsin endothermic process.It fitted the data which was the effect of adsorption time of methylene blue and basic fuchsin on PVFM foam to determine the reaction rate constant of different temperature. The results show that adsorption dynamics of the two dyes are in line with quasi-second order kinetics equation and the diffusion of external solution is decisive step of rate. In the experimental temperature and concentration of study range, Langmuir and Freundlich isotherm equations can be a good description of the adsorption behaviors of methylene blue and basic fuchsin on PVFM foam. The adsorption free energy change of two processes is negative, they are spontaneous process. The adsorption enthalpy change of two processes are negative and positive respectively.