Synthesis of composite sorbent for the treatment of aqueous solutions contaminated with methylene blue dye.

To apply the principles of sustainability, this study aims to prepare the composite sorbent from mixing of solid wastes that resulted from activities of treatment plants for wastewater and water supply. The manufacturing process depends on the mixing of sewage sludge with waterworks sludge at different proportions and the best mixture is modified by ferric nitrate solution. The prepared composite sorbent was evaluated as permeable reactive barrier (PRB) in the capturing of methylene blue (MB) dye presented in the simulated groundwater. Results proved that the suitable mixture of composite sorbent consisting of 0.25 g sewage sludge with 0.75 g waterworks sludge coated with aqueous solution of 2 g of Fe(NO3)2 achieved the maximum sorption capacity. In comparison with Freundlich model, Langmuir expression described the sorption measurements in a well manner; so, the chemisorption is governed by the removal of MB with maximum adsorption capacity reached to 268.98 mg/g. Kinetic measurements could be more representative by pseudo-first-order model and this means that the sorption process is supported by physical forces. Finally, the effects of inlet concentrations and bed thickness on the migration of MB front were simulated in an efficient manner by COMSOL Multiphysics 3.5a package with root mean squared errors not in excess of 0.152.

Waste foundry sand/MgFe-layered double hydroxides composite material for efficient removal of Congo red dye from aqueous solution.

We aimed to obtain magnesium/iron (Mg/Fe)-layered double hydroxides (LDHs) nanoparticles-immobilized on waste foundry sand-a byproduct of the metal casting industry. XRD and FT-IR tests were applied to characterize the prepared sorbent. The results revealed that a new peak reflected LDHs nanoparticles. In addition, SEM-EDS mapping confirmed that the coating process was appropriate. Sorption tests for the interaction of this sorbent with an aqueous solution contaminated with Congo red dye revealed the efficacy of this material where the maximum adsorption capacity reached approximately 9127.08 mg/g. The pseudo-first-order and pseudo-second-order kinetic models helped to describe the sorption measurements, indicating that the physical and chemical forces governed the removal process.

Predominant Mechanisms in the Treatment of Wastewater Due to Interaction of Benzaldehyde and Iron Slag Byproduct.

Iron slag is a byproduct generated in huge quantities from recycled remnants of iron and steel factories; therefore, the possibility of using this waste in the removal of benzaldehyde from contaminated water offers an excellent topic in sustainability field. Results reveal that the removal efficiency was equal to 85% for the interaction of slag and water contaminated with benzaldehyde at the best operational conditions of 0.3 g/100 mL, 6, 180 min, and 250 rpm for the sorbent dosage, initial pH, agitation time, and speed, respectively with 300 mg/L initial concentration. The maximum uptake capacity of iron slag was 118.25 mg/g which was calculated by the Langmuir model. Physical sorption may be the major mechanism for the removal of benzaldehyde onto iron slag based on the analysis of isotherm and kinetic sorption data and thermodynamically, the process was spontaneous and endothermic. Finally, the X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM) and energy-dispersive spectroscope (EDS) tests for reactive material certified that the dissolution of calcium oxide can enhance the removal of benzaldehyde by the formation of bridge cations.