ADSORPTION CHARACTERIZATION OF CO(II) IONS ONTO CHEMICALLY TREATED QUERCUS COCCIFERA SHELL: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDIES

Quercus coccifera shell (QCS), a relatively abundant and inexpensive material, is currently being investigated as an adsorbent to remove cobalt(II) from water. Before the adsorption experiments, QCS was subjected to chemical treatment to provide maximum surface area. Then, the kinetics and adsorption mechanism of Co(II) ions on QCS were studied using different parameters such as adsorbent dosage, initial concentration, temperature, contact time, and solution pH. The loaded metals could be desorbed effectively with dilute hydrochloric acid, nitric acid, and 0.1 M EDTA. The Langmuir and Freundlich models were used to describe the uptake of cobalt on QCS. The equilibrium adsorption data were better fitted to Langmuir adsorption isotherm model. The maximum adsorption capacity (qm) of QCS for Co(II) was 33 mg g-1. Various kinetic models were used to describe the adsorption process. The adsorption followed pseudo second-order kinetic model. The intraparticle diffusion was found to be the rate-limiting step in the adsorption process. The diffusion coefficients were calculated and found to be in the range of 3.11×10−6 to 168.78×10−6 cm2s-1. The negative DH* value indicated exothermic nature of the adsorption

PREPARATION AND APPLICATION OF KOH IMPREGNATED SEPIOLITE AS A SOLID BASE CATALYST FOR BIODIESEL PRODUCTION USING MICROWAVE IRRADIATION

An active basic solid catalyst for biodiesel production was obtained via KOH impregnation onto sepiolite support followed by high temperature calcination.The transesterification of rapeseed oil over the resulting nanocomposite structure was investigated using a microwave reactor. Morphological and structural characterization of sepiolite and KOH impregnated sepiolite was carried out by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis. Optimization of the operational parameters such as methanol to oil molar ratio, catalyst loading, reaction temperature and reaction time were examined. Reusability of the catalyst and the reactions utilizing waste cooking oil were also studied. Obtained results indicated that the basic heterogenous catalysis diminishes the saponification during the transesterification reaction and that microwave heating was very effective at shortening the biodiesel production time. However, the reusability of the KOH impregnated sepiolite catalysts and their structural stability require further investigation

Adsorption of Cd(II) ions from aqueous solutions using activated carbon prepared from olive stone by ZnCl2 activation

This study is aimed to remove Cd(II) ions from aqueous solutions by adsorption. As adsorbent, activated carbon prepared from olive stone, an agricultural solid by-product was used. Different activating agent (ZnCl2) amounts and adsorbent particle size were studied to optimize adsorbent surface area. The adsorption experiments were conducted at different parameters such as, adsorbent dose, temperature, equilibrium time and pH. According to the experiments results, the equilibrium time, optimum pH, adsorbent dosage were found 60 min, pH > 6 and 1.0 g/50 ml respectively. The kinetic data supports pseudo-second order model and intra-particle model but shows very poor fit for pseudo-first order model. Adsorption isotherms were obtained from three different temperatures. These adsorption data were fitted with the Langmuir and Freundlich isotherms. In addition, the thermodynamic parameters, standard free energy (Delta G(0)), standard enthalpy (Delta H-0), standard entropy (Delta S-0) of the adsorption process were calculated. To reveal the adsorptive characteristics of the produced active carbon, BET surface area measurements were made. Structural analysis was performed using SEM-EDS. The resulting activated carbons with 20% ZnCl2 solution was the best sample of the produced activated carbons from olive stone with the specific surface area of 790.25 m(2) g(-1). The results show that the produced activated carbon from olive stone is an alternative low-cost adsorbent for removing Cd(II)