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Removal of organic pollutants and metal ions from produced water by adsorption, using prepared activated carbon (AC) from sewage sludge, with chemical activations using NaOH, KOH and ZnCl2 separately and pyrolysis at different temperatures (500, 600 and 700 °C). Pure sludge and prepared ACs were analyzed using FTIR and XRD. The results showed 18% crystallinity compared to that of commercial AC, which has 44% crystallinity. The results of FTIR demonstrate that the properties of the post-treated affect the final products depending on the method used and that it contains similar functional groups to those present in the commercial AC, but at a higher peak intensity. Adsorption treatments were carried out at 25, 35 and 45 °C solution temperatures. The results showed that the removal of pollutants from produced water using prepared AC with all types of chemical activations reached 99.5%, such as commercial AC with 0.06 g dosage of adsorbent at pyrolysis temperatures of 500 and 600 °C and a solution temperature of 25 °C. The obtained results refer to the mechanism of exothermic reaction and physical adsorption. It was observed that despite the lower dosage of adsorbent of 0.01 g, a sufficient treatment of pollutants was achieved. This reveals the effectiveness of using sewage sludge as a cheap adsorbent. Also, using pure sewage sludge, the adsorption data showed a 95.2% removal of the pollutants. This result indicated that pure sludge has an efficient adsorption capacity and can be utilized as a cheap and environmentally friendly material. For the removal of manganese and cadmium metal ions from the produced water, the resultant data showed that more than 90% of manganese was adsorbed and more than 97% of cadmium was adsorbed, especially when using pure sewage sludge and prepared activated carbon with NaOH chemical activation at pyrolysis temperatures of 500 °C and 600 °C. [ABSTRACT FROM AUTHOR]

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The goal of this research was to investigate the efficacy photocatalysis with natural solar radiation and artificial UV radiation for disinfecting total coliforms in biologically treated wastewater. The effect of TiO2 dosage and irradiation time on total coliform inactivation as measured by log reduction values (LRV), removal of BOD, COD, turbidity, and effluent properties as measured by pH and conductivity was investigated. Two sets of experimental equipment were constructed, one for using solar UV light and the other for using artificial UV light. After four hours of irradiation with 60 mg/L TiO2, photocatalysis achieved LRVs of 1.4 and 1, respectively, under UV and solar radiation. COD and BOD were reduced by 67% and 50% respectively under UV and solar radiation after two hours of irradiation with 60 mg/L TiO2. Turbidity was reduced by 71%. Both conductivity and acidity of the effluent were reduced as TiO2 concentration was increased. Photocatalysis with natural solar radiation produced disinfection results that were comparable to that of efficient UV light exposure. Artificial UV light and natural solar radiation can be combined in photocatalysis process to form a hybrid process. [ABSTRACT FROM AUTHOR]

Advanced oxidation process is a promising technology for remediation of organic pollutants at ambient conditions. Several experiments of photocatalytic decolorization of Tartrazine compound using TiO2and UV light have been carried out for enhancing the characteristic of the oxidation kinetics. The experimental results revealed that photo oxidation process was strongly dependent on UV light intensity, and an improvement of 98% was achieved for 75% increase in the light intensity. The reaction rate constant in respect to UV light intensity was larger by order of 10 compared to other considered parameters. The second important parameter that affecting the decolorization rate was the hydraulic time constant (τ) showed an improvement of 79.4% of the decolorization process. The catalytic oxidation process is considered similar to a batch chemical reactor and covered by the first-order reaction rate. A negative impact of 66.67% was obtained by increasing the dye concentration. The results showed that the increased level of TiO2concentration did not necessarily improve the rate of degradation of pollutant. The repeatability of photocatalytic process was also tested and after reusing the recycled TiO2, the rate of color degradation was still efficient with respect to initial dye concentration. It appeared that the photo-oxidation process was favorable at neutrality conditions or slightly higher pH for solutions consisting of anions. [ABSTRACT FROM PUBLISHER]

Activated carbon (AC) has been used as an adsorbent for centuries as a result of its ability to remove a large variety of compounds from contaminated waters. The objective of this study was to investigate the removal of methanol by adsorption and the use of advanced oxidation process for the regeneration of the exhausted AC as an alternative to thermal, biological, and chemical methods that are currently applied. Several experimental tests were carried out to examine the ability of AC for adsorbing methanol from methanol–water mixture. The results show fast saturation of the AC and short breaking time, especially for solutions consisting of methanol above 3% vol. However, adsorption capacity of exhausted AC with methanol, after washing, showed an improvement in its adsorption capacity over that of fresh AC. This improvement may be due to that methanol may harsh the surface of AC causing an increase in the sizes of pores and cavities. Large cavities were micrograph using scanning electron microscope (SEM). After saturation, AC was regenerated using the photo-catalytic process, the adsorption capacity of AC was fully restored. The results showed that the titanium dioxide with the aid of UV light can easily regenerate the AC by oxidizing the organic compounds adsorbed on the surface of AC. It was observed that the increase of UV light intensity had a positive effect on adsorption capacity. However, the increases of TiO2concentrations had a limited effect on the adsorption capacity of the AC. [ABSTRACT FROM PUBLISHER]

Preparation of activated carbon from date seeds and the possibility of using it as an adsorbent were evaluated. Pyrolysis of date seeds under nitrogen flow and activation with carbon dioxide was performed at three different temperatures (700, 800, and 900°C). SEM micrographs of activated carbon produced at 900°C indicate a rough structure on the surface with more mesopores than that produced at lower temperatures. In addition, EDS analysis showed that it has higher oxygen surface groups. However, the yield was 16.5% compared with 18.9% and 20.9% at 800, 700°C, respectively. Batch adsorption of cobalt on S900 showed type III adsorption isotherm at three studied temperatures (25, 35, and 45°C). This type of isotherm was explained using Freundlich's and BET models that showed very good agreement with the experimental data. The Gibbs free energy change was calculated as --4.154, --4.374, and --4.595 kJ/mol at 25, 35, and 45°C, respectively. The adsorption of cobalt was found to be endothermic process (DH° = 2.415 kJ/mol) and entropy-driven rather than enthalpy-driven with DS° = 0.022 kJ/mol.K. [ABSTRACT FROM AUTHOR]