D S Divyadharshini, S Harinivalli, Nitish Kumar, G Arthanareeswaran, Ramalinga Viswanathan Mangalaraja
BACKGROUND
Metronidazole is a persistent antibiotic pollutant in aquatic environments, posing ecological and health risks due to its chemical stability and low biodegradability. This study evaluates the influence of three graphene quantum dot (GQD) modifications (heteroatom-doped N,S-GQDs, surface-hydroxylated NaOH-GQDs, and polymer-modified PANI-GQDs) and MIL-100(Fe) synergy in a hybrid PVDF/PEI membrane for efficient antibiotic removal.
RESULTS
The modified membranes exhibited Metronidazole rejection rates of 51%, 90%, and 63% for N,S-GQD, NaOH-GQD, and PANI-GQD coatings, respectively, compared to 68% for the uncoated hybrid membrane. The photocatalytic efficiency followed the order NaOH-GQD > N,S-GQD > uncoated membrane > PANI-GQD, with the NaOH-GQD-coated membrane showing the highest degradation rate (K1 = 0.0119 min−1, R2 = 0.99).
The simultaneous valorization of waste batteries, CO₂, and biomass holds significant importance for advancing a circular economy.
RESULT
In this work, valuable metals (Ni, Co, Mn) were recovered via an acid-leaching and reduction method. These recovered metals were subsequently employed to in-situ grow NiCoMn layered double hydroxide (LDH) on kaolinite (Kaol) nanosheets through a microwave-assisted hydrothermal process. This strategy successfully constructs an S-scheme heterojunction composite photocatalyst (NiCoMn-LDH/Kaol) for the efficient coupling of photocatalytic CO₂ reduction with 5-hydroxymethylfurfural (HMF) oxidation. Results demonstrated that the NCM-LDH-9/Kaol catalyst prepared at pH = 9 achieved the highest CO production rate of 235 μmol·g⁻1·h⁻1 and an exceptional 92.2% selectivity towards 2,5-diformylfuran (DFF) from HMF oxidation under full-spectrum irradiation. Mechanistic studies revealed that the S-scheme heterojunction between LDH and Kaol significantly enhanced the separation of photogenerated charge carriers. Simultaneously, the oxidation of HMF provides the necessary protons for CO₂ reduction, establishing a synergistic enhancement.
Advanced oxidation processes are considered one of the most promising techniques for removing persistent organic pollutants in water. To achieve efficient degradation of sulfonamides (SAs), cobalt sulfide (CoS) was synthesized and used as a catalyst for the activation of peracetic acid (PAA) to build a new advanced oxidation system (CoS/PAA).
Results
The reaction conditions of catalyst dosage, PAA concentration, initial pH and substrate concentration were systematically investigated using sulfamethoxazole (SMX) as a model pollutant. At the optimized conditions (80 mg L−1 CoS and 0.5 mmol L−1 PAA), four SAs (sulfisoxazole, sulfadiazine, sulfadimethoxine and SMX, each at 5 mg L−1) could be completely degraded within 2–10 min. This CoS/PAA system could withstand interference from inorganic anions of Cl− and H2PO4−, and the leaching of cobalt ions in treated water was well below the environmental quality standards of 1 mg L−1 in China. The quenching experiment revealed that organic free radicals (RO•) played a key role in the degradation process. Moreover, a removal rate of 95.03% for SAs in complex pond water was achieved.
Samuel David Settle, Richard Law, Elizabeth Susan Heidrich
BACKGROUND
Microbial electrochemical technologies (METs) enable separation of ammonium from nutrient-rich waste streams, such as sludge return liquors, using bioanodes that consume organic matter to generate electrical current. Quantification of ammonia recovery performance in pilot scale METs treating real wastes under industrially relevant conditions is scarce. This study evaluates ammonium removal rates and transport mechanisms in a cassette-style pilot microbial electrolysis cell (MEC) treating real sludge return liquor for the first time at a wastewater treatment facility at ambient temperatures (3–18 °C).
RESULTS
Preliminary screening of the return liquor determined it contained enough electrons within readily biodegradable organic matter to support bio-electrochemical ammonium recovery. Recovery potentials were 8.8 and 5.9 based on soluble COD and total VFA content, respectively. Current densities of 0.15 to 0.20 A m−2 were achieved which allowed the catholyte to accumulate total ammonia nitrogen (TAN) from 238 to 1521 mg L−1 in around 15 days. The highest TAN removal rate was 1.7 g m−2 d−1 and migration contributed most to ammonium transport despite the cells generating low current densities.
The ethanol–acetonitrile–benzene ternary mixture frequently arises in chemical production and exhibits a Serafimov class 3.1–2 phase behavior; however, studies on its separation remain relatively limited. Considering the pressure-sensitive characteristics of this system, this work develops and evaluates extractive distillation and pressure-swing extractive distillation processes to achieve efficient separation of the azeotropic mixture.
RESULTS
Vapor–liquid equilibrium analysis identified glycerol as the optimal entrainer, and process parameters were optimized using a particle swarm optimization algorithm. On this basis, heat integration and heat pump technologies were incorporated to establish a comprehensive 4E evaluation framework covering energy, economics, environment, and efficiency.
The microalga Dunaliella sp. FACHB-847 is known for its ability to accumulate high levels of lutein, making it a promising source of natural carotenoids. To enhance its suitability for industrial-scale production, various strategies have been explored to boost carotenoid yields. In this study, 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene, was exogenously applied to promote carotenoid accumulation in Dunaliella sp. FACHB-847.
RESULTS
Exogenous ACC application (15 mM) stimulated algal growth, with biomass reaching 1.70 g L−1, and increased the chlorophyll content (chlorophyll a and b) to 29.51 mg L−1, resulting in a 1.37-fold increase compared to the control. High lutein productivity (4.19 mg g−1) was achieved under 15 mM ACC treatment, representing a 0.68-fold increase compared to the control. Upregulated expression of key genes in the carotenoid biosynthesis pathway, including lycopene β-cyclase, lycopene ε-cyclase, and β-carotene hydroxylase under ACC treatment contributed to the promoted carotenoid accumulation. Furthermore, the combination of ACC with high photon flux density (180 μmol m−2 s−1) synergistically enhanced both biomass production and pigment synthesis. Notably, even under low photon flux density (72 μmol m−2 s−1), ACC-treated cultures accumulated higher carotenoid levels than those of the high-light control group.
Khanifah Khanifah, Akhmad Syafi'i Ma'arif, Ahmad Shoiful, Muh. Nur Khoiru Wihadi
BACKGROUND
Carbon dioxide is a greenhouse gas that significantly influences global warming and climate change. Consequently, developing new materials that exhibit high adsorption capabilities, high regeneration efficiency, mild regeneration conditions, economic viability, and low operational costs for industrial applications is important. This study aimed to develop two novel pentametallic MnNiCoCu/X (X = Al, Fe) layered doubled hydroxides (LDHs) and their hybrids with polyoxometalates (POMs) through the hydrothermal technique, to achieve effective CO2 capture.
RESULTS
The results revealed that two new pentametallic MnNiCoCu/Al LDH (L1) and MnNiCoCu/Fe LDH (L2), as well as their hybrids with Keggin-type POMs (PW12O403−) (L1α and L2β), have been formed in the solid. Structural characterization using Fourier transform infrared spectroscopy, powder X-ray diffraction, and field emission scanning electron microscopy–energy-dispersive X-ray spectroscopy revealed the presence of the pentametallic component in the LDH structure and its change after hybrid formation. The surface area of all solids ranged from 11.69 to 94.45 m2 g−1, with pore volumes from 0.025 to 0.075 cm3 g−1; pore widths were from 3.19 to 9.36 nm, and were influenced by the presence of Al3+ or Fe3+ in the pentametallic layered and Keggin ion in the solid. All solids exhibited a porous morphology characterized by the arrangement of crystallites. The particle size of all solids ranged from 40.21 to 80.23 nm. The LDHs and their hybrids revealed a significant quantity of strong basic sites, rendering them suitable for CO2 capture. We observed that the different trivalent ions (Al3+ and Fe3+) in the pentametallic LDH structure and their hybrids influenced the properties and capacity of CO2 capture.
The development of efficient and stable catalysts for wastewater treatment is limited by metal leaching under reaction conditions. Copper-based Fenton-like systems offer advantages over iron catalysts, but their long-term stability is influenced by synthesis parameters, including the precursor selection, which controls copper dispersion, oxidation states and metal–support interactions.
RESULTS
Cu/Al₂O₃ catalysts were synthesized by wet impregnation using oxide, nitrate, sulfate and chloride precursors, calcined at 900 °C and tested in the catalytic wet peroxide oxidation of phenol at 70 °C. All catalysts achieved complete phenol conversion within 30 min, but significant differences in mineralization and copper leaching were observed. Nitrate- and sulfate-derived catalysts (CuAN, CuAS) exhibited smaller crystallite sizes, higher copper dispersion and stronger Cu–support interactions, leading to lower leaching (~35%) and stable activity. Oxide- and chloride-derived catalysts (CuAO, CuACl) showed higher leaching (>40%) but slightly higher total organic carbon removal, attributed to the homogeneous contribution of dissolved copper. X-ray photoelectron spectroscopy and Auger analyses confirmed variable Cu+/Cu2+ distributions depending on precursor type, with higher Cu+ content correlating with enhanced redox activity. Total organic carbon conversions ranged from 86% to 89%, and buffered conditions further improved radical stability and mineralization efficiency. Comparative analysis with literature highlighted the competitive performance of CuAN and CuAS catalysts, obtained through a simple impregnation route without dopants.
Abdul Matin Ali, Nibedita Kapil, Susmita Sen Gupta, Krishna G Bhattacharyya
BACKGROUND
Interactions of graphene calcium ferrite (GCF) nanocomposite with fluoride ions in aqueous medium have been investigated to explore the utilization of GCF as an adsorbent for fluoride removal. The investigation was based on batch adsorption studies with fluoride concentration, adsorbent amount, pH, interaction time, and temperature as the process variables.
RESULTS
The experimental results indicate a strong influence of pH on fluoride adsorption on GCF. The initial fluoride concentration also influenced the process, with adsorption decreasing from 79.5 to 70.1% when fluoride concentration increased from 1.0 to 9.0 mg L−1 with a constant adsorbent load of 2.0 g L−1. The interaction kinetics were tested with respect to Lagergren first-order and second-order kinetics and with respect to Elovich equation, liquid film diffusion model, and intraparticle diffusion. The interactions appeared to be very close to second-order kinetics (k2 = 0.0518 g mg−1 min−1 at 303 K). The data yielded a Langmuir monolayer capacity of ~11.90 mg g−1 at 303 K. The uptake of fluoride was enhanced by a small increase in the solution temperature.
The study investigates how different aqueous phases—purified water, two mineral waters, and one thermal mineral water—affect the physicochemical and mechanical properties of oil-in-water emulsions stabilized with two non-ionic alkyl polyglucoside (APG) emulsifiers—Montanov™68 (Cetearyl Alcohol and Cetearyl Glucoside) and Montanov™82 (Cetearyl Alcohol and Coco Glucoside). Comprehensive characterization included pH and conductivity measurements, microscopy, rheology, and texture analysis. Given the routine adjustment of topical emulsions to skin-relevant pH, rheological measurements were repeated after adjusting each formulation to pH 5.5.
RESULTS
Unlike electrolyte effects typically described for ionic surfactant systems, this work demonstrates that ion identity and mineralization level of the aqueous phase significantly influence structure and mechanical properties of emulsions stabilized by non-ionic APG emulsifiers, which are generally assumed to be insensitive to electrolytes. Distinct mineral compositions produced measurable changes in viscosity, firmness, and viscoelastic behaviour, revealing that mineral waters actively modulate lamellar gel network organization. In contrast, adjusting the pH to 5.5 resulted in minor changes, confirming that aqueous ionic composition is the dominant factor shaping the final emulsion properties.
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