No abstract

The adsorption of sulfur compounds from petroleum refinery wastewater on a chemically modified activated carbon (MAC) was investigated. The modification technique (nitric acid, hydrogen peroxide and thermal modification) enhanced the removal capacity of carbon and therefore decreases cost-effective removal of sulfide from refinery wastewater. Adsorption equilibrium and kinetics data were determined for sulfur removal from real refinery wastewater. The data were evaluated according to several adsorption isotherm and kinetics models. The Freundlich isotherm fitted well with the equilibrium data of sulfur on different adsorbents, whereas the kinetics data were best fitted by the pseudo-second-order model. Insights of sulfide removal mechanisms indicated that the sorption was controlled through the intraparticle diffusion mechanism with a significant contribution of film diffusion. The MAC adsorbent was found to have an effective removal capacity of approximately 2.5 times that of non-modified carbon. Using different MAC, sulfides were eliminated with a removal capacity of 52 mg g(-1). Therefore, MAC can be utilized as an effective and less expensive adsorbent for the reduction of sulfur in refinery wastewater.

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 m.g and 0.11 cm.g, respectively. Several types of acidic and basic oxygenated surface groups were highlighted. The point of zero charge (pH) 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 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, and q = 250 mg.g) and Sips (n = 0.84, K = 0.003 L.mg, and q = 232.6 mg.g) 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.

Phenolic resin and waste cotton fiber were investigated as green precursors for the successful synthesis using a soft template approach of a composite carbon with carbon nanofibers embedded in a porous carbon network with ordered and periodically pore structure. The optimal composite carbon (PhR/NC-1), exhibited a specific surface area of 394 m 2 ·g −1 with the existence of both microporosity and mesoporosity. PhR/NC-1 carbon was evaluated as an adsorbent of Alizarin Red S (ARS) dye in batch solution. Various operating conditions were examined and the maximum adsorption capacity of 104 mg·g −1 was achieved under the following conditions, i.e., T = 25 • C, pH = 3, contact time = 1440 min. The adsorption and desorption heat was assessed by flow micro-calorimetry (FMC), and the presence of both exothermic and endothermic peaks with different intensity was evidenced, meaning a partially reversible nature of ARS adsorption. A pseudo-second-order model proved to be the most suitable kinetic model to describe the ARS adsorption according to the linear regression factor. In addition, the best isotherm equilibrium has been achieved with a Freundlich model. The results show that the eco-friendly composite carbon derived from green phenolic resin mixed with waste cotton fibers improves the removal of ARS dye from textile effluents.

No abstract