The paper presents the modification of Phu Yen diatomite by oxidation-reduction reaction between Fe (II) and KMnO4 salts in solution pH = 6 on the diatomite surface. Characteristics of modified materials and the influence of research factors on these characteristics were investigated using techniques XRD, EDX, XPS, SEM, TEM, BET. Arsenic adsorption capacity of modified materials, the influence of environmental factors on the adsorption capacity were also investigated and evaluated. The results showed that mixed oxide-modified diatomite has higher arsenic adsorption capacity than natural diatomite and modified diatomite by individual oxides.
Abstract
In this study, cationic polyacrylamide (CPAM) modified diatomite and cetyl trimethyl ammonium bromide (CTAB) modified diatomite were synthesized and used as conditioner in sewage sludge dewatering. The effects of these two types of modified diatomite on the dewaterability and settling performance of activated sludge were studied. The mechanism of the two types of modified diatomite in the activated sludge system was elucidated. The efficiency of CPAM-modified diatomite was better than that of CTAB-modified diatomite in improving the settleability and dewaterability performance of sludge. The results indicated that specific resistance to filtration (SRF) was decreased from 8.52×1012m/Kg to 0.92×1012 m/Kg, and the water content in the remaining sludge cake after pumping filtration was decreased from 92.2% to 68.1%. by adding 0.4% of CPAM-modified diatomite and pH=3.5, which result in optimal sludge settling of activated sludge. Further studies showed that the polymer/surfactant adsorbed in diatomite increased sludge dewaterability and improved the sedimentation rate as a result of stripping extracellular polymer substances (EPS) and damaging the internal structure of sludge conduce bound water releasing. According to scanning electron microscope(SEM) images, two types of modified diatomite powder not only kept the porous, but also shown more complete and uniform structure in comparison to nature diatomite.
The MnO2-modified diatomite was obtained by wet chemical methods. The specific structure of the material has been determined by modern physicochemical methods. The results showed that the surface of diatomite was coated by the manganese oxide nanoparticles. The prepared MnO2-diatomite material is a good adsorbent for the removal methyl orange (MO) in water. The adsorption kinetics of MO on modulation materials are consistent with the pseudo-second-order kinetics model. Therefore, MnO2-modified diatomite materials could be promising sorbents for removing MO.
Study on the modification of Phu Yen diatomite by mixed Fe-Mn oxide and the use of the modified material as an arsenic removal adsorbent in water environment
