Recovery of dyes and salts from highly concentrated (dye and salt) mixed water using nano-filtration ceramic membranes

Green triiron tetraoxide@Algae (Fe3O4@Algae) nanoparticles for highly efficient removal of lead (Pb2+), cadmium (Cd2+), and aluminum (Al3+) from contaminated water: an isothermal, kinetic, and thermodynamic study

Developing and producing a versatile adsorbent for effective wastewater treatment remains a significant obstacle to wastewater processing. As the objective is to eliminate various metal ions (lead, cadmium, and aluminum) from wastewater, we therefore strategically designed and synthesized new iron oxide nanoparticles (Fe3O4 NPs) based on the green algae called triiron tetraoxide@algae nanoparticles (Fe3O4@Algae NPs) that grow in the same contaminated water using a facile one-pot green synthetic method. Investigations were conducted into the adsorption circumstances, including pH, starting concentration, adsorbent dosage, and adsorption time. More importantly, great absorption of lead, cadmium, and aluminum was achieved, with 97.5%, 81.3%, and 75.13%, respectively. The best conditions were 60 min, 0.1 g of nanoparticles, at 25 °C, and 150 mL of water containing 30 mg/L of Pb, Cd, and Al, with pH 6 for Cd and Pb and pH 5 for Al. To analyze the kinetics and equilibrium adsorption data and to evaluate the interaction between the metal ions and the adsorbent, a variety of kinetic and isotherm models were employed. The Langmuir isotherm and a pseudo-second-order were the best ways to look at the adsorption isotherm and kinetics data for how the Fe3O4@algae removes metal ions. Furthermore, thermodynamic studies showed that the adsorption process was an exothermic, favorable, and spontaneous reaction. For the elimination of Al(III), Pb(II), and Cd(II), the Fe3O4@algae experimental adsorption capacity was 33.8 mg/g, 56.70 mg/g, and 36.58 mg/g, respectively. The composite of Fe3O4@algae nanoparticles was characterized using several analytical techniques including scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and UV-vis spectroscopy. In addition, the material exhibited notable durability and recyclability, with the metal removal effectiveness remaining at a high level even after undergoing five successive adsorption cycles. This study paves the way to the use of green nanotechnology for eco-friendly, cheap, and rapid techniques that can be used in the purification of wastewater.

Development of inorganic and mixed matrix membranes for application in toxic dyes-contaminated industrial effluents with in-situ treatments

Dyes are the most ubiquitous organic pollutants in industrial effluents. They are highly toxic to both plants and animals; thus, their removal is paramount to the sustainability of ecosystem. However, they have shown resistance to photolysis and various biological, physical, and chemical wastewater remediation processes. Membrane removal technology has been vital for the filtration/separation of the dyes. In comparison to polymeric membranes, inorganic and mixed matrix (MM) membranes have shown potentials to the removal of dyes. The inorganic and MM membranes are particularly effective due to their high porosity, enhanced stability, improved permeability, higher enhanced selectivity and good stability and resistance to harsh chemical and thermal conditions. They have shown prospects in filtration/separation, adsorption, and catalytic degradation of the dyes. This review highlighted the advantages of the inorganic and MM membranes for the various removal techniques for the treatments of the dyes. Methods for the membranes production have been reviewed. Their application for the filtration/separation and adsorption have been critically analyzed. Their application as support for advanced oxidation processes such as persulfate, photo-Fenton and photocatalytic degradations have been highlighted. The mechanisms underscoring the efficiency of the processes have been cited. Lastly, comments were given on the prospects and challenges of both inorganic and MM membranes towards removal of the dyes from industrial effluents.

Feasibility of Forward Osmosis to Recover Textile Dyes Using Single Salts and Multicomponent Draw Solutions

The textile industry generates large volumes of water characterized mainly by an intense color coming from dyes that are difficult to process due to their synthetic base and the presence of aromatic components. Due to the stricter regulation on the discharge of these effluents, in order to reduce dye waste before discharge into natural channels, alternatives are being sought to manage this wastewater. In this work, the concentration of dyes in simulated wastewater from the textile industry was studied by forward osmosis (with a cellulose triacetate CTA membrane), with the aim of concentrating the dye for its future recovery and reincorporation into the production process. Two dyes of different nature were evaluated to study the efficiency of the proposed process, using NaCl and reverse osmosis brine from a model seawater desalination solution as extraction solutions. It was observed that dye type (reactive or direct) and their charge influence the color rejection with the forward osmosis membrane used. It was able to concentrate the dyes in the feed solution up to approximately 55% with the reverse osmosis brine from the model seawater desalination solution. Finally, the results demonstrate that the FO process is a promising option for concentrating dyes present in wastewater from the textile industry in order to reuse them in the dyeing process.