Effect Of Surfactant On Cadmium Adsorption By Penicillium Simplicissimum And Mechanism Discussion

The effects of surfactant on Cd2+adsorption by Penicillium simplicissimum and mechanism discussion are investigated. A certain amount of surfactant (Triton X-100, SDS, Saponin and RL), respectively, to the liquid medium of Penicillium simplicissimum, which were made of biosorbents to adsorb Cd2+. It is studied the effects of different experimental conditions on cadmium adsorpton. Meanwhile, the adsorption mechanism was studied on the best experimental conditions.Experimental results showed that pH is an important parameter affecting the adsorption process. The adsorption capacities of pretreated biosorbents increase significantly as the pH values increased from1.0to5.0, and then decreased at pH5.0-7.0. The maximum adsorption capacities of Cd2+were obtained at pH5.0for the pretreated P. simplicissimum and at pH6.0for the intact P. simplicissimum, respectively.Adsorption kinetics analysis showed that the adsorption equilibrium was reached after about4h. The data were fitted by the linear regression method of Langmuir model and Freundlich model. The research discovered that the experimental adsorption isotherms were in good agreement with the Langmuir model.The maximum adsorption capacity was65mg/g for the0.025%RL-pretreated P. simplicissimum, which was59mg/g for the0.025%Saponin-pretreated P. simplicissimum, which was54mg/g for the0.001%SDS-pretreated P. simplicissimum, and which was52.75mg/g for the0.05%Triton X-100pretreated P. simplicissimum, respectively. However, the maximum adsorption capacity was38mg/g for the intact P. simplicissimum. Therefore, the surfactant-pretreated P. simplicissimum was a promissing candidate for cadmium adsorption. Biosurfactants showed a greater advantage than that of chemical surfactant. The preference of surfactants for Cd2+adsorption was as follows:RL>Saponin>SDS>Triton X-100.The interactions mechnism between Cd2+and functional groups on the cell wall surface of the biosorbents were identified by SEM, EDAX and FTIR analysis. The research discovered that addtion of surfactants changed the cell structur of P. simplicissimum, which affected cadmiun adsorption by changing certain functional groups. The potassium peak was weakened even vanished before and after adsorption, which proving that adsorption process included ion-exchange mechanism. It was indicated that benzene ring, amino and hydroxyl groups played major roles in the Cd2+adsorption. The optimizd experimental condition and mechnism discussion have a certain value to aim at developing new efficient biosorbents. And it provided the theoretical basis for further actual production.