ABSTRACT
Polyphenols are natural compounds with enhanced antioxidant properties. They are present in relatively high concentrations in fruit/vegetable by-products. Therefore, there is a need for the development of efficient and cost-effective methods for the separation and purification of these valuable compounds. Traditional extraction with organic solvents needs to be switched to novel methods that are more efficient, with reduced extraction times and low consumption of organic solvents. Aiming at developing sustainable processes for the separation and purification of phenolic compounds, we used three model compounds, namely resveratrol, quercetin, and gallic acid, to investigate ionic liquid-based aqueous biphasic systems (IL-ABSs) formed by cholinium-based IL in combination with polypropylene glycol with a molecular mass of 400 g/mol (PPG400). The ABS composition in the two-phase region was selected according to a previously determined phase diagram. Extraction studies indicated the preferential partition of resveratrol and quercetin toward the hydrophobic PPG-rich phase that is mainly dominated by its hydrophobic nature and the strong salting-out effect of ILs. On the other hand, due to its considerably hydrophilic nature, gallic acid preferentially migrates toward the IL phase. The achieved results from grape stem extract demonstrated high extraction efficiencies of cholinium dihydrogen phosphate (~99% for resveratrol for the PPG phase and 78% for gallic acid for the IL phase), with considerable selectivity, demonstrating promising outcomes for potential applications.
ABSTRACT
Extensive use of pesticides resulting in their accumulation in the environment presents a hazard for their non-target species, including humans. Hence, efficient remediation strategies are needed, and, in this sense, adsorption is seen as the most straightforward approach. We have studied activated carbon fibers (ACFs) derived from viscose fibers impregnated with diammonium hydrogen phosphate (DAHP). By changing the amount of DAHP in the impregnation step, the chemical composition and textural properties of ACFs are effectively tuned, affecting their performance for dimethoate removal from water. The prepared ACFs effectively reduced the toxicity of treated water samples, both deionized water solutions and spiked tap water samples, under batch conditions and in dynamic filtration experiments. Using the results of physicochemical characterization and dimethoate adsorption measurements, multiple linear regression models were made to reliably predict performance towards dimethoate removal from water. These models can be used to quickly screen among larger sets of possible adsorbents and guide the development of novel, highly efficient adsorbents for dimethoate removal from water.
ABSTRACT
The release and accumulation of pesticides in the environment require the development of novel sustainable technologies for their removal. While adsorption is a classical approach, the design of new materials with enhanced adsorption properties could rationalize the remediation routes and decrease potential risks for their non-target organisms, including humans. More importantly, the use of adsorbents and their synthesis should be implemented in a sustainable and environmentally friendly manner. In this contribution, we studied the adsorption of organophosphorus pesticides (OPs) dimethoate, malathion, and chlorpyrifos on viscose fiber-derived activated carbon fibers (ACFs). The most efficient adsorption was found for chlorpyrifos, followed by malathion and dimethoate, while material properties were correlated with OP uptake. These ACFs are extremely efficient for chlorpyrifos adsorption, with experimentally observed adsorption capacitances reaching 240 mg g-1. Detailed analysis suggests that chlorpyrifos is physisorbed on ACF surfaces and that increased surface hydrophilicity reduces the uptake. Studied ACFs have great potential for practical application. They can reduce OPs' concentrations to such levels that no acute neurotoxic effects of the studied OPs in spiked tap water samples are seen, even for starting concentrations up to 104 times higher than the allowed ones. Finally, this study presents possible guidance for developing even more efficient and environmentally friendly adsorbents for chlorpyrifos, the most toxic among studied OPs.
