Abstract
Hierarchical porous carbon materials made from cork were fabricated using a facile and green method combined with air activation, without any templates and chemical agents. The influence of air activation on the texture and other surface characteristics of the carbon materials were evaluated by various characterization techniques. Results indicate that air oxidation can effectively improve the surface area and the hierarchical porous structure of carbon materials, as well as increase the number of oxygen-containing functional groups on the carbon surface. The specific surface area and the pore volume of the carbon material activated by air at 450 °C (C800-M450) can reach 580 m2/g and 0.379 cm3/g, respectively. These values are considerably higher than those for the non-activated material (C800, 376 m2/g, 0.201 cm3/g). The contents of the functional groups (C–O, C=O and O–H) increased with rising activation temperature. After air activation, the adsorption capacity of the carbon materials for methylene blue (MB) and methyl orange (MO) was increased from 7.7 and 6.4 mg/g for C800 to 312.5 and 97.1 mg/g for C800-M450, respectively. The excellent dye removal of the materials suggests that the porous carbon obtained from biomass can be potentially used for wastewater treatment.
Highlights
Fast economic and industrial growth has led to the discharge of large volumes of dye wastewater from the rubber, leather, paper, printing and pharmaceutical sectors, among others
A facile and green hydrothermal-carbonization method combined with air activation was used to fabricate functional porous oxygen-rich carbon materials with natural cork as raw material without using any chemical reagents or templates
Post-carbonization of conducted at high temperatures under N2 atmosphere to improve the degree of graphitization and the porous structure (Figure 1)
Summary
Fast economic and industrial growth has led to the discharge of large volumes of dye wastewater from the rubber, leather, paper, printing and pharmaceutical sectors, among others. Methods of dye wastewater treatment mainly include adsorption, electrochemical oxidation, addition of chemical thinners, degradation of pollutants via degradation, separation of solid particles via surface filtration and biological techniques [1,2,3,4,5,6,7,8,9,10]. Among these approaches, adsorption is considered a practical method for removing harmful dyes from wastewater owing to its superior performance, cost-efficiency and lowest possible impact on the environment. Various biomass materials, including pine nut shell, celtuce leaves, coconut shell, lignin, rice husks, cellulose, bamboo, tannin and grape stalk, have far been used to fabricate porous
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