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Abstract-Bottom ash is a waste material obtained from electricity generation through combustion of coal at the Mae Moh power plant in Thailand. The adsorption of Cd (II) and Zn (II) ions from aqueous solutions onto bottom ash was studied using batch experiments. The effect of pH, contact time and temperature were investigated. Adsorption isotherm data for metal ions was analyzed by the Langmuir and Freundlich isotherms. The Freundlich isotherm properly described the adsorption data for all studied temperatures. The results revealed that the adsorption kinetics followed pseudo-second-order kinetic model. Thermodynamic parameters such as Gibbs free energy change (∆G°), enthalpy change (∆H°) and entropy change (∆S°) were investigated. The calculated values showed that the adsorption process for both Cd (II) and Zn (II) ions was endothermic.

The absorbable porous material, especially gelatin porous film, is widely used for surgical use to stop bleeding, but its price is quite high. Thus, a new material at lower price with desirable properties is required. This article presents an approach to prepare a porous film of silk fibroin-rice starch (SF-RS) modified with trisodium trimetaphosphate (STMP). The preparation was performed using freeze-drying method aiming to increase the porosity and improve some other properties of the modified porous film. The solutions of SF and RS (5 : 95 weight ratio) and STMP were mixed and adjusted to pH 12 before being neutralized to pH 7 and freeze-dried for 48 h. Result from the SEM images showed that the average pore size of the SF-RS film increased from 17 to 126 lm after STMP was added up to 5.0% w/w. Similar to the SF-RS-STMP hydrogel, the linkages within the modified SF-RS porous film also occurred mainly between the OAH groups of RS and the triphosphate group of STMP. Moreover, cross-linking density of the porous film increased with the increasing content of STMP, evidenced from the increase of relative methylene blue adsorption. The addition of STMP also affected the physical properties of the modified porous film such as degree of swelling, oxygen permeability, but not the water solubility. Whereas, the residual ash of the modified porous films was lower than 2.0% and the degradation of the film ceased after soaking in 0.01M PBS solution for about 2 weeks.