Degradation of malachite green by dielectric barrier discharge plasma.

Oxidative decomposition of aqueous organic pollutant malachite green (MG) was studied in a dielectric barrier discharge reactor operated under ambient conditions. Total organic carbon content analysis confirmed the mineralization of the pollutant leading to the formation of carbon dioxide, which was confirmed by an infrared analyzer. Typical results indicated that the degradation rate increases with increasing applied voltage and decreases with increasing concentration. Dye degradation followed first order kinetics. The intermediate products formed during the degradation of MG were identified by a high resolution mass spectrometer (HR-MS) and proposed a plausible mechanism for the mineralization process.

Low-cost adsorbents from bio-waste for the removal of dyes from aqueous solution.

Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m(2)/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H(2)O(2)-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics.