Immobilisation of phosphonium-based ionic liquid in polysulfone capsules for the removal of phenolic compounds, with an emphasis on 2,4-dichlorophenol, in aqueous solution

Techno-economic assessment of waste mandarin biochar as a green adsorbent for binary dye wastewater effluents of methylene blue and basic fuchsin: Lab- and large-scale investigations

Treating polluted wastewater effluents on a large-scale requires the development of high performance and cost-effective adsorbents. The recycling of waste mandarin peels, an environmentally friendly, and copiously available waste biomass into biochar (MRBC), has been approached. In the context of finding affordable and effective solutions for depollution of wastewater, MRBC was used for the adsorption of two dyes: methylene blue (MB) as well as basic fuchsin (BF) from their individual solutions and binary combinations. Batch adsorption studies were performed by employing the Box-Behnken (BB) design. The adsorption competency of dyes was analyzed to find the percentage removal (%R) and the adsorption capacity (qe, mg/g). The dependent parameters (qe and %R) were determined as a function of pH, dose of MRBC (AD), contact time (CT), and concentration of methylene blue [MB]/ basic fuchsin [BF]. Removal of 98.14% of MB and 83.18% of BF was successfully achieved. Equilibrium experiments depicted that Langmuir and Freundlich models suit adsorption of dyes. The maximum adsorption capacity (qmax) was 99.11 (MB) and 78.01 mg/g (BF), individually. However, when the dyes are combined, the qmax decreased to 57.09 and 68.52 mg/g for MB and BF, correspondingly. The cost of MRBC was estimated to be ∼ 4 USD/kg, while the overall cost of wastewater treatment was estimated to be 1.06 USD/m3/year.

Adsorption behavior of aged polybutylece terephthalate microplastics coexisting with Cd(II)-tetracycline

Microplastics (MPs) are one of the emerging classes of pollutants that can be infiltrated into any aqueous solutions from disposed toxic metals and antibiotics, further exacerbating the potential biotoxicity of MPs. However, the research on the interaction between MPs and various pollutants is limited. Therefore, in this study, the changes in toxicity of polybutylece terephthalate (PBT) MPs were assessed following adsorption of heavy metals and antibiotics. The adsorption behavior of Cd(II) and tetracycline (TC) on ultraviolet (UV) light-aged PBT was investigated. The results demonstrated that the Cd(II) adsorption behavior could be described by the pseudo-second-order kinetic and Langmuir isothermal models, while the TC adsorption behavior has well fitted using Elovich and Sips models. The whole adsorption process occurred via either external diffusion or internal diffusion. The interactions between aged PBT and pollutants were evaluated under different environmental conditions, such as solution pH and the concentrations of dissolved organic matter and cations. The amounts of Cd(II) and TC adsorbed were higher in the competitive systems than the single solution, which might attribute to the formation of Cd(II)-TC complexes and aged PBT functional group changes. The results of two-dimensional correlation spectroscopy (2D-COS) describes the sequence of functional group transformation during the uptake of Cd(II)-TC by aged PBT in binary systems. These findings identify a strong interaction between aged PBT and contaminants, establishing the potential fate of aged MPs under natural aquatic environment conditions.

Application of a phosphonium-based ionic liquid for reactive textile dye removal: Extraction study and toxicological evaluation

Textile dyeing processes are known for their negative environmental impacts due to the production of aqueous effluents containing toxic dyes. Therefore, new wastewater treatment processes need to be developed to treat such effluents, including Liquid-Liquid Extraction (LLE) process using Ionic Liquids (IL). This work aimed to evaluate the application of the hydrophobic IL trihexyltetradecylphosphonium decanoate to extract black, navy, and royal reactive dyes from water and evaluate the toxicological aspects of the resulting water stream. We investigated the effect of selected parameters, such as pH (2-12), temperature (20-50 °C), salt effects, dye concentration (0.5-50 mg/L), and phase volume ratio (900-9000) on the dye extraction. The results showed extraction yields as high as 97% for the three dyes and an extraction capacity of approximately 300 mg/g for black and navy dyes and 400 mg/g for royal. The toxicity tests involved Lactuca sativa, Triticum aestivium L, and Daphnia magna as bioindicators. The difference between the toxicity of the dye solutions before and after extraction was not statistically significant when L. sativa and Triticum aestivum L were used as bioindicators. However, the extracted solution showed increased toxicity towards D. magna due to traces of IL. Overall, the IL has a high extraction capacity for the black, navy, and royal dyes. Nevertheless, further studies on LLE associated with other processes must be carried out to reduce the risk linked to the toxicity of IL transferred to the water.