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Activated carbons, RS-1, RS-2, and RS-3, prepared from rice straw with ( NH4 )2 HPO4 activation were used as adsorbents for removing phenols from aqueous solutions. The maximum adsorption capacities of phenol for RS-1, RS-2, and RS-3 were 163.9, 172.9, and 200.0 mg/g, respectively. The equilibrium data were analyzed by the Langmuir, Freundlich, and Temkin models. It displayed that Langmuir isotherm fitted to the results best. The dimensionless parameter RL indicated the favorable nature of the adsorption of phenol. Otherwise, the kinetic rates were well explained by pseudo-second-order model. According to the results, activated carbon derived from waste rice straw can be a high-performance adsorbent for wastewater treatment. [ABSTRACT FROM AUTHOR]

Activated carbons, RS-1, RS-2, and RS-3, prepared from rice straw with ( NH4 )2 HPO4 activation were used as adsorbents for removing phenols from aqueous solutions. The maximum adsorption capacities of phenol for RS-1, RS-2, and RS-3 were 163.9, 172.9, and 200.0 mg/g, respectively. The equilibrium data were analyzed by the Langmuir, Freundlich, and Temkin models. It displayed that Langmuir isotherm fitted to the results best. The dimensionless parameter RL indicated the favorable nature of the adsorption of phenol. Otherwise, the kinetic rates were well explained by pseudo-second-order model. According to the results, activated carbon derived from waste rice straw can be a high-performance adsorbent for wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: Effects of different pretreatment protocols in (NH4)2HPO4 activation of rice straw on porous activated carbon evolution were evaluated. The pore structure, morphology and surface chemistry of obtained activated carbons were investigated by nitrogen adsorption, scanning electron microscopy and Fourier transform infrared spectroscopy. It was found that pretreatment combining impregnation with (NH4)2HPO4 and preoxidation could significantly affect the physicochemical properties of prepared activated carbons. The apparent surface area and total pore volume as high as 1154m2/g and 0.670cm3/g were obtained respectively, when combined process of impregnation followed by preoxidation at 200°C and activation at 700°C was carried out. Meanwhile, the activated carbon yield and maximum methylene blue adsorption capacity up to 41.14% and 129.5mg/g were achieved, respectively. The results exhibited that (NH4)2HPO4 could be an effective activating agent for producing activated carbons from rice straw. [ABSTRACT FROM AUTHOR]