Exposure of multiwalled carbon nanotubes (MWCNTs) to oxidizing acids and other oxidants introduces oxygen-containing functional groups such as hydroxyl, carboxyl, and carbonyl groups onto the surface. This research evaluated how changes in oxygen concentration and distribution of oxygen-containing functional groups influenced the sorption of aqueous zinc and cadmium on MWCNTs. Sorption results with natural char, activated carbon, and a suite of MWCNTs (of varying surface oxygen content) were obtained. Results confirmed that surface oxygen enhances the sorption of both Zn[II] and Cd[II] from aqueous solution. Although Zn[II] sorbed more strongly than Cd[II] for all materials studied, surface oxidation had more effect on the sorption of Cd[II] than of Zn[II]. Additional sorption experiments with Zn[II] and 16 MWCNTs of varying surface oxidation level and functional group distribution revealed the relative contributions of different types of surface sites to sorption. Sorption isotherms were fit using a two-site Langmuir adsorption model that incorporated the independent characterization of functional group distribution. Results showed that carboxyl-carbon sites were over 20 times more energetic for zinc sorption than unoxidized carbon (graphenic-carbon) sites, though both site types are important contributors to sorption.

Thermodynamic and kinetics of adsorption of basic dyes (methylene blue and basic blue 3) on wood charcoal activated at 800 °C, prepared from Bombax Cieba (M78D) was investigated. Equilibrium data was obtained using batch method at temperatures of 10 °C to 50 °C. It was found that adsorption increase with increase in temperature. The Langmuir isotherm model describe the equilibrium of adsorption. Thermodynamic parameters such as ΔS°, ΔH° and ΔG° were calculated. From the values of ΔH° and ΔG°, it was concluded that the adsorption process is endothermic and spontaneous in nature. To determine kinetics parameter Lagergren equation was applied, and it was found that the reaction proceed through first order kinetic mechanism.

-Carbon prepared from the wood of Ailanthus altissima, at 400 and 800 o C was used to adsorb acid blue 1 from aqueous solution at 10 o C and 45 o C. Characterization by XRD, SEM, EDS and FTIR shows that the surfaces contain functional groups like carboxyl which disappear at 800 0 C and thus favor the exposure of more porous structural surfaces which enhance the adsorption capacity. Relatively high amounts of carbon with respect to oxygen were found with the increase in activation temperature. First order, Bangham and parabolic models were found to fit the adsorption kinetic data. The reaction rate increased with the increase in temperature of adsorption/activation. Thermodynamic parameters like ΔE ≠ , ΔH ≠ , ΔS ≠ and ΔG ≠ were calculated. The negative values of ΔS ≠ reflect the decrease in the disorder of the system at the solid-solution interface, during adsorption. Gibbs free energy (ΔG ≠ ) represents the driving force for the affinity of dye for the carbon and it decreased with the increase in adsorption/activation temperature.

The samples of Red Palm Oil (RPO) were irradiated with gamma rays using a Cobalt‐60 source (ISSLEDOVATEL, CIS), to dose levels of 1, 5, 10, 15 and 20 KGy and kept for the storage period of 8 weeks along with an untreated control at ambient conditions. The samples were tested for physical characteristics, i.e., Peroxide Value (POV), Iodine Value (IV), Free Fatty Acid value (FFA), Anisidine Value (AV), Color and β‐Carotene. Results revealed that the POV, FFA, and AV were higher in the irradiated samples than the control at the completion of the experimental period. It was also observed that these effects were positively correlated with increasing the irradiation dose. However, a reversed trend was noted in the case of Iodine Value, color and β‐Carotene.

A B S T R A C TThe adsorption of Acid Blue 129 (AB129) from aqueous solution onto hydrochloric acid-activated montmorillonite clay (HCl-bentonite) was investigated. The activated clay was characterized by scanning electron microscopy, energy dispersive spectroscopy, and BrunauerEmmett-Teller surface area. Batch adsorption experiments were performed to investigate the effects of pH, contact time, initial dye concentration, and temperature (10, 20, 30, and 40˚C). Acidic conditions was suitable for higher adsorption of AB129, and kinetic studies demonstrate that the process followed a pseudo-second-order model. An activation energy of 23.858 kJ mol −1 was obtained for adsorption process. Adsorption data were fitted to Freundlich and Langmuir isotherms and various adsorption parameters have been calculated. Standard enthalpy (ΔH˚) and standard entropy (ΔS˚) were −44.90 kJ mol −1 and −68.44 kJ mol −1 K −1 , respectively, showing that overall adsorption process was exothermic and is spontaneous in nature with a decrease in the disorder of the system at the dye/adsorbate interface. However, the mechanism of the dye-Bentonite interaction is likely to be very complicated, involving a wide range of sites having different energy considerations. The activated clay was effective toward adsorption of AB129. The results show that activated bentonite clay could be employed as low-cost materials for the removal of acid dyes from colored effluents.