Sustainable conversion of agro-wastes into useful adsorbents

Preparation and characterization of raw andactivated carbon derived from three different selectedagricultural wastes: kola nut pod raw and activated (KNPRand KNPA), bean husk raw and activated (BHR and BHA)and coconut husk raw and activated (CHR and CHA) wereinvestigated, respectively. Influences of carbonization andacid activation on the activated carbon were investigatedusing SEM, FTIR, EDX, pHpzcand Boehm titration tech-niques, respectively. Carbonization was done at 350°C for2 h followed by activation with 0.3 M H3PO4(ortho-phosphoric acid). Results obtained from SEM, FTIR, andEDX revealed that, carbonization followed by acid acti-vation had a significant influence on morphology and ele-mental composition of the samples. SEM showed well-developed pores on the surface of the precursors after acidtreatment, FTIR spectra revealed reduction, broadening,disappearance or appearance of new peaks after acid acti-vation. EDX results showed highest percentage of carbonby atom respectively in the order BHA[KNPA[CHArespectively. The pHpzcwas found to be 5.32, 4.57 and 3.69for KNPA, BHA and CHA, respectively. Boehm titrationresult compliments that of pHpzc, indicating that the sur-faces of the prepared adsorbents are predominantly acidic.This study promotes a sustainable innovative use of agro-wastes in the production of cheap and readily availableactivated carbons, thereby ensuring more affordable waterand effluent treatment adsorbents

Sorption of cadmium (II) ion from aqueous solution onto sweet potato (Ipomoea batatas L.) peel adsorbent:characterisation, kinetic and isotherm studies

Sweet potato peels was used for the removal of Cd (II) from aqueous solutions. The residue was characterised using SEM, EDX, XRF, N2 BET, TGA and ATR-FTIR. Sorption of Cd (II) was carried out by varying pH, contact time and initial ion concentration at 25 °C and the results showed a strong dependence of the ion removal on the adsorbate pH with optimum observed at pH 7. Kinetics of Cd (II) sorption indicates optimum time of 180 min and the removal of Cd (II) occurred via a fast initial uptake. This was modelled using the pseudo first, pseudo-second and intraparticle diffusion models. The pseudo-first order gave a better description of the uptake kinetics than the pseudo-second order model with an r2 value of 0.99. The intraparticle-diffusion model showed that sorption had multi-linear steps indicating that the intraparticle-diffusion is not the only rate controlling step in Cd (II) sorption. FTIR analysis of the PTPS before and after adsorption of Cd (II) indicates that some functional groups such as hydroxyl, carbonyl and carboxylate groups may be involved in metal ion sorption. Isotherm modelling of Cd (II) sorption was carried out using the Langmuir and Freundlich isotherms using a non-linear optimisation. The Langmuir isotherm gave a better fit for Cd (II) sorption and maximum loading capacity (qmax) was 18 mg g−1 with an isotherm constant of 5.21 × 10−3 l mg−1 and r2 value of 0.99 at 25 °C. Hence, the PTPS residue was found to be a promising adsorbent for Cd (II) removal from aqueous streams

Liquid–liquid extraction of methylene blue dye from aqueous solutions using sodium dodecylbenzenesulfonate as an extractant

The extraction of methylene blue dye from aqueous solutions has been investigated using sodium dodecylbenzenesulfonate as an extractant. The various diluents used were benzene, toluene, xylene and dichloroethane. Dichloroethane was found to be the most effective diluent for the extraction of the dye. The investigated parameters, governing the extraction of the dye, were equilibrium time, pH of the dye solution, extractant concentration, dye concentration, temperature and aqueous to organic phase ratio. The dye was totally extracted at the optimum conditions. The dye loaded in the organic phase was stripped using various types of acids as stripping agent; complete recovery of the dye was achieved using 0.5 M thiourea in 1 M HCl. Keywords: Liquid–liquid extractant, Methylene blue, Stripping, Extraction, Diluen

Ultrasounds assisted one-pot oxidative desulfurization of model fuel using green synthesized aluminum terephthalate [MIL-53(Al)]

Abstract Oxidative desulfurization (ODS) is considered to be one of the most promising desulfurization processes as it is energy-efficient and requires mild operating conditions. In this study, a novel green synthesized Al- based metal–organic framework with high surface area has been synthesized hydrothermally using waste polyethylene terephthalate bottles (PET) as a source of terephthalic acid as an organic linker. The prepared Al based MOF have been characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The catalytic activity of the prepared Al-MOF was evaluated in the oxidative desulfurization (ODS) of both modeled and real crude oil samples. The different operating parameters (temperature, time, catalyst dose, oxidant loading and sonication) on the ODS performance have been optimized. The optimal conditions for maximum removal of thiophene from modeled oil samples were found to be 30 min, 0.5 g of catalyst and 1:3 oil to oxidant ratio. Under the optimized conditions, sulfur removal in real oil samples obtained from Alexandria petroleum company was 90%. The results revealed that, the presented approach is credited to cost-effectiveness, environmental benignity, and ease of preparation, predicting great prospects for desulfurization of fuel oils on a commercial level

Extraction of heavy metals from aqueous solutions in a modified rotating disc extractor

Extraction of Cu+2 from dilute aqueous solutions as a case study by liquid cation exchanger in a modified rotating disc extractor was studied. The liquid cation exchanger consisted of naphthenic acid dissolved in an inert carrier kerosene. Variables studied were: initial concentration of Cu+2, disc rotational speed, concentration of naphthenic acid, flow rates of continuous and dispersed phase, degree of roughness, and number of rotating discs. The rate of extraction increased with increasing rotational speed, concentration of naphthenic acid, flow rate of dispersed phase, degree of roughness and number of discs to a certain number, while increasing Cu+2 concentration and flow rate of continuous phase decreased the rate of extraction. All variables were correlated by the dimensionless mass transfer equation. Possible practical applications of the present data in treating aqueous waste from different sources such as petrochemical industries, electroplating, and hydrometallurgical processes was highlighted