ACS Sustainable Resource Management最新文献

The increasing rate of fish morbidity and grave concerns regarding the long-term implications on human health with exposure to N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) from waste tires have brought to light the urgency to isolate this compound in the environment. Toward this end, we focus on removing 6PPD from waste tires by using solvent-based extraction. However, a major challenge in solvent-based extraction is identifying a conducive solvent that is nontoxic, efficient, and economically and environmentally feasible. Thus, we developed a physics-informed computational methodology for identifying conducive solvents to extract 6PPD from waste tires. The methodology spans various scales from quantum mechanical calculations to process development and environmental impact. Starting with a database of 2000+ solvents, we sequentially screened the database to identify 7 candidates. This was followed by a detailed investigation of these candidates from economic and environmental perspectives. We subsequently performed experimental verification of these solvents for the extraction of 6PPD from crumb rubber using batch microwave-assisted extraction. The developed physics-based methodology could be applied to solvent selection in other applications as well.

Vinyl polymer prepared from 2-methylene-4H-benzo[d][1,3]dioxin-4-one (MBDO), a cyclic ketene acetal ester, is a chemically recyclable polymer that is hydrolyzed to salicylic acid (SA) and acetic acid (AA). Despite this potential, the polymer, poly-MBDO, required a strong acid or base in organic solvent for the hydrolysis. In this study, we report the quantitative conversion of poly-MBDO to phenol by treatment in high-temperature water. Hydrolysis of poly-MBDO afforded SA, which underwent rapid decarboxylation to phenol. For example, poly-MBDO quantitatively afforded phenol upon heating in water at 300 °C for 5 min and freeze-drying. Although the hydrolysis of the main chain was incomplete, the products were volatile and removed by drying the reaction mixture, leaving the residue of pure phenol. Since SA is industrially synthesized from phenol and CO₂, the synthesis of poly-MBDO from phenol is in principle possible. The quantitative conversion of poly-MBDO to phenol can also be considered as carbon-resource recovery, since phenol is a raw material for various fine chemicals.

The development of degradable polymers and their degradation methods are important for resource recovery. Herein, phenol was quantitatively recovered from a vinyl polymer of cyclic ketene acetals using high-temperature water.

One major group of aqueous emerging contaminants is antibiotics. The occurrence in potable water is increasing, and their presence has several unintended consequences, including antibiotic resistance. This has led to over seven hundred thousand deaths annually, a value projected to hit 10 million by 2050, hence the need for their removal. Most current potable water treatment technologies are not well suited to antibiotic elimination. Hence, photocatalytic degradation was studied here. A comparative photo-degradation of two antibiotics, ciprofloxacin (CPF) and tetracycline (TC), was investigated using a ZnO photocatalyst and its Ag-doped (2.5%, 5%, and 7.5%) species. The Ag-doping did not significantly affect the ZnO crystal structure but enhanced the specific surface area and pore size values and lowered the band gap energies. The 2.5 wt % Ag-ZnO expressed the best properties and exhibited up to 50% and 43% enhancement in the degradation of CPF and TC, respectively, compared to the pristine ZnO photocatalysts. It exhibited excellent reusability, retaining ∼82% and 91% of the initial degradation of CPF and TC, respectively, after four cycles. The observed optimum parameters for the effective degradation of both antibiotics are a mass of ∼35 mg at pH 9 (alkaline medium) using a concentration of 12 mg/L in a solution volume of 350 mL over a time range of 120 min. The 2.5 wt % Ag-ZnO is a promising applicable material for potable water treatment.

After comparative photo-degradation of two antibiotics, ciprofloxacin and tetracycline, using a ZnO photocatalyst and its Ag-doped species, 2.5 wt % Ag-ZnO was deemed a promising applicable material for potable water treatment.

Crude oil and petroleum-based fuel spills represent a persistent threat to marine ecosystems. Economical and sustainable sorbents are required to mitigate environmental hazards arising from this pollution. This study employs a low-density fluorinated porous polysulfide polymer made by the direct reaction of sulfur (S), used cooking oil(s) (UCO) such as used cooking mustard oil (UCO-M), used cooking soybean oil (UCO-S), and used cooking rice bran oil (UCO-R), 2,3,4,5,6-pentafluorostyrene (PFS), and table salt (NaCl) to fill this demand. The polymer has an attraction for hydrocarbons such as crude oil and petroleum-based fuel, allowing it to quickly remove them from water because of the hydrophobicity of sulfur and cooking oil. The fluorinated polysulfide can absorb 2.5 mL g^–1 engine oil and form a water–oil mixture. The captured oil has been recovered by simple mechanical compression and reused again to clean up oil spills under environmentally relevant conditions, up to multiple cycles (4 cycles with >85% adsorption capacity). As sulfur is a byproduct of petroleum, polysulfide stands out for being entirely produced from recycled waste, contributing waste to wealth initiatives and a circular economy.

Sludge-derived hydrochar is rich in phosphorus (P), and heavy metals are also present. Hence, fully recovering P while removing heavy metals as much as possible is a key part of ensuring sustainable P resource recycling and utilization. Citric acid, activated alumina, and NaOH were separately selected as acid extraction, adsorbent, and desorbent for the first time to conduct P recovery from hydrochar. The effects of the adsorbent dosage, initial P concentration, and time on P adsorption were investigated. Kinetics and adsorption isotherm models were employed to analyze the adsorption data. Various characterization techniques were comprehensively applied to further elucidate the adsorption mechanisms. The results showed that the P adsorption rate was positively correlated with the dosage but negatively correlated with the initial P concentration during the experimental parameter range. The P adsorption capacity varied inversely with the adsorption rate. Moreover, at 825 mol·L^–1 P and 0.5 g adsorbent dosage conditions, the maximum adsorption capacity was achieved (7.3 mg·g^–1) within 30 min with an 80.2% P adsorption rate at equilibrium (48 h). The P recovery rate could reach 72.6%, with the removal of Zn, Mn, and Cr exceeding 99%. The corresponding mechanisms involve ligand exchange, electrostatic attraction, anion exchange, and surface precipitation.

Postconsumer polystyrene (PS) wastes are a major contributor to microplastic contamination of the biosphere, which could be reduced or eliminated by developing strategies to upcycle these wastes into useful materials. Four postconsumer PS waste streams from flatware (PSF), cups (PSC), lids (PSL), and packaging materials (PSP), as well as a mixture of all four streams (PSM), were reacted with elemental sulfur at 230 °C to afford the corresponding high-sulfur-content materials (HSMs) PSF₉₀, PSC₉₀, PSL₉₀, PSP₉₀, and PSM₉₀, respectively. Glass transitions in these HSMs were observed at temperatures ranging from −36 to −39 °C, with these values being characteristic of oligo/polysulfide chains. Compressional and flexural strength measurements revealed that these HSMs were competitive with ordinary Portland cement and C62 Brick. To gain insight into the microstructural features within these HSMs, cumene was reacted with sulfur at 230 °C and then depolymerized with LiAlH₄, yielding small-molecule products amenable to GC-MS analysis. These reactivity studies provided compelling evidence that PSF₉₀, PSC₉₀, PSL₉₀, PSP₉₀, and PSM₉₀ contain the expected oligo/polysulfide cross-links between PS chains at 3° benzylic and 2° aliphatic carbons in addition to the formation of benzothiophene moieties.

This research aims to develop technology that can improve low-grade iron ore containing a large amount of α-FeOOH and gangue to the same level as the high-grade iron ores that are conventionally used. The main goal is to optimize the alkaline hydrothermal treatment conditions for iron ore when using a flow-type reactor for constructing a development framework for an upgrading process for low-grade iron ore. Gangue removal extents during 5 M NaOH hydrothermal treatment increased with increasing treatment temperature, with around 80% of Si, Al, and P removed by treatment at 250 °C. The removal extents also increased with increasing NaOH concentration, decreasing particle size, and decreasing solid-liquid ratio. The ore species was found to have virtually no effect on gangue removal by alkaline hydrothermal treatment. Based on the results obtained, the optimal parameters for gangue removal were a particle size of <1000 μm, a solvent concentration of >0.1 M, and a heating temperature of 250 °C. The FeOOH present in the iron ore changed to Fe₂O₃ after alkaline hydrothermal treatment. Furthermore, this method was also effective for gangue removal from sorted particles with a large gangue content.

The current chemical industry primarily relies on basic molecules from petroleum. Nevertheless, these molecules, known as building block chemicals, can be synthesized from biomass. Therefore, the aim of this work was to evaluate the production of formic acid (FA) and levulinic acid (LA) from agro-industrial waste, particularly potato peel (PP), using a microwave-assisted hydrothermal treatment. The sample was conditioned and characterized by a physicochemical analysis. The results indicated that the PP had a high moisture content (≈ 82%) and a total carbohydrate content of 39.8%. Subsequently, a 2³ factorial design was established to study the effect of temperature (100 to 180 °C), H₂SO₄ concentration (0 to 0.6 M) and reaction time (5 to 30 min.) on FA and LA conversion. From the experimental trials, it was possible to establish that the highest FA (2.51%) and LA (13.77%) yields were obtained at 180 °C and 0.6 M H₂SO₄. When ANOVA analysis was performed, it was observed that the temperature and H₂SO₄ concentration were the most influential parameters on FA and LA conversion. Finally, to improve the process, some tests were performed with a new set of temperatures (160, 180, and 200 °C) and acid concentrations (0.3, 0.6, and 1.0 M), and a previous hydrolysis stage was established, where the highest FA (3.19%) and LA (27.95%) yields were found at 160 °C and 1.0 M H₂SO₄. This work showed that it is possible to obtain value-added products from agro-industrial waste such as PP; however, further studies and experiments focused on improving the yield of the process are still required.

This study presents a rapid and convenient approach for the carbamation of starch through the microwave irradiation of its mixture with an excess of urea. In this process, urea served not only as a dielectrically lossy material conducive to microwave heating but also as a solvent in its molten state and a source of isocyanic acid. The formation of starch carbamate was confirmed by the appearance of ν(C═O) and ν(C–N) vibrations in the FTIR spectrum, along with the detection of a carbamate carbonyl signal in the ¹³C NMR spectrum. The resultant derivative, with a degree of substitution of 0.71, exhibited exceptional cold-water solubility, resistance to retrogradation, and cold solubility in organic solvents such as DMSO, N,N-DMF, and DMAc. Additionally, this microwave-assisted technique could be modified to include other agents with urea. For example, introducing sodium dihydrogen orthophosphate to the starch-urea mixture led to simultaneous phosphorylation. Control experiments indicated that this concurrent phosphorylation-carbamation introduced phosphodiester linkages between the starch molecules in addition to carbamation, resulting in an absorbent material. This absorbent was capable of absorbing about 2200% of distilled water, even in its crude, unpurified form. This easy-to-synthesize absorbent, particularly in its crude form, holds immense promise in agriculture for providing combined nitrogen and phosphorus supplementation along with water retention.