Elimination of organic contaminants from water by microporous carbon fiber aerogel obtained from cotton

In this study, carbon fiber aerogel (CFA) was prepared by controlled pyrolysis of cotton at 800 degrees C in flowing N2 for 90 min and subsequent chemical treatment by 2 M potassium hydroxide and further carbonization. The fabricated CFA was characterized using different techniques such as FESEM, FTIR, XRD, BET, and BJH. The results showed that the specific surface area of CFA was 1109 m(2)/ g and the structure was microporous with an average pore diameter of 2 nm and pore volume of 0.57 (cm(3)/g). The aerogel was then applied as an adsorbent for the removal of methylene blue (MB) and p-nitrophenol (PNP) as organic pollutant models from water. Various parameters like initial concentration, adsorbent dosage, and solution pH were examined to investigate the adsorption behavior. The equilibrium data of MB adsorption followed the Langmuir model with a maximum capacity (q(max)) of 256.41 mg/g while the PNP data conformed to the Freundlich isotherm model with a qmax of 192.30 mg/g at room temperature. The kinetic of both pollutants followed the pseudo-second-order model. Thermodynamic studies revealed that the adsorption of MB was endothermic (Delta H degrees similar to 6.25 kJ/mol) while the PNP adsorption was exothermic (Delta H degrees similar to - 3.61 kJ/mol). The values of Delta G degrees and Delta H degrees suggested that the adsorption was of physical nature. [GRAPHICS] .