Carbonaceous adsorbents derived from textile cotton waste for the removal of Alizarin S dye from aqueous effluent: kinetic and equilibrium studies.

Recycling cotton waste derived from the textile industry was used as a low-cost precursor for the elaboration of an activated carbon (AC) through carbonization and zinc chloride chemical activation. The AC morphological, textural, and surface chemistry properties were determined using different analytical techniques including Fourier transform infrared, temperature programmed desorption-mass spectroscopy, nitrogen manometry and scanning electron microscopy. The results show that the AC was with a hollow fiber structure in an apparent diameter of about 6.5 μm. These analyses indicate that the AC is microporous and present a uniform pore size distributed centered around 1 nm. The surface area and micropore volume were 292 m2.g-1 and 0.11 cm3.g-1, respectively. Several types of acidic and basic oxygenated surface groups were highlighted. The point of zero charge (pHPZC) of theca was 6.8. The AC performance was evaluated for the removal of Alizarin Red S (ARS) from aqueous solution. The maximum adsorption capacity was 74 mg.g-1 obtained at 25 °C and pH = 3. Kinetics and equilibrium models were used to determine the interaction nature of the ARS with the AC. Statistical tools were used to select the suitable models. The pseudo-second order was found to be the most appropriate kinetic model. The application of two and three isotherm models shows that Langmuir-Freundlich (n = 0.84, K = 0.0014 L.mg-1, and q = 250 mg.g-1) and Sips (n = 0.84, K = 0.003 L.mg-1, and q = 232.6 mg.g-1) were the suitable models. The results demonstrated that cotton waste can be used in the textile industry as a low-cost precursor for the AC synthesis and the removal of anionic dye from textile wastewater.