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A B S T R A C TThe impact of various operating parameters, including pH (2-12), concentrations of modified zeolite (0.1-1.25 g/L), initial concentration of Cr (VI) (0.1-1.5 mg/L), and contact time (5-120 min), was investigated on the removal of Cr (VI) from water through different experimental runs in the batch system. The results showed that modified zeolite had best performance for the removal of Cr (VI) at the pH 7. The time required for the removal of 90.95% of the Cr (VI) from a 1 mg/L solution was about 80 min using modified zeolite. The equilibrium assessment illustrated that the Langmuir model is the best fit for the experimental data, which attains a maximum adsorption capacity of 4.4 mg/g. Pseudo-second-order kinetic model was found to adequately describe the adsorption process. In the final part of the study, the efficacy of modified natural zeolite was examined to simultaneously removal of Cr (VI) and As (V) from aqueous solution. In summary, modified natural zeolite is an efficient in performance, simple to operate, and economical process and thereby affordable technology for the removal of Cr (VI) from the contaminated water source.

The chemical composition of the volatile oil from aerial parts of Perovskia abrotanoides Karel. has been studied by GC and GC-MS. Twenty-nine components (98.9% of the total composition) were identified. 1,8-Cineole (32.4%), myrcene (13.0%), α α α α α-pinene (10.2%), camphor (9.1%), β β β β β-caryophyllene (7.9%), α α α α α-humulene (6.4%), camphene (5.0%) and α α α α α-bisabolol (2.6%) were found to be the major constituents of the oil. The oil of P. abrotanoides was characterized by a high content of monoterpenes (78.9%), whereas sesquiterpenes contained only 20.0% of the essential oil.

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In this research, the degradation of the insecticide diazinon was studied using a new hybrid catalyst consisting of magnesium oxide nanoparticles (nano-MgO), carbon nanotubes (CNTs), and graphite (Gr), nano-MgO@CNT@Gr, under various experimental conditions.

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Catalytic ozonation has recently been used as a new means of contaminant removal from water and wastewater. In this study, bone charcoal (BC), a new catalyst prepared under laboratory conditions, was used to catalyze the ozonation of humic substances (HS) in aqueous solutions. The catalytic effect of bone charcoal and the relevant parameters of this ozonation process (solution pH, temperature, scavenger effect, humic acids concentration and BC dosage) were investigated. In the catalytic ozonation experiments, the degradation kinetics was investigated. The reaction rate and the rate constant were determined. The results showed that using a BC catalyst in the ozonation of HS produced a 1.43-and 1.56-fold increase in reaction rates compared to the sole ozonation processes (SOP) under acidic and alkaline conditions, respectively. Furthermore, the applicability of heterogeneous catalytic ozonation with bone charcoal (HCOBC) to humic acid degradation was evaluated by performing comparisons with H 2 O 2 , O 3 , O 3 /H 2 O 2 and O 3 /H 2 O 2 /BC processes. With the use of the Arrhenius equation, the activation energy (E a ) was calculated to be 10 kJ mol -1 . The results also showed that under the different temperatures, the reaction of the catalytic ozonation of HS was defined as diffusion controlled in accordance with the activation energy. These findings suggest that the HCOBC can be applied as an efficient and feasible method for the removal of HS from water.