Nur Najwa Abdul Talib, Noor Hana Hanif Abu Bakar, Mohamad Abu Bakar, Anwar Iqbal, Nurul Hayati Yusof, dan Rosniza Hamzah
BACKGROUND
Lanthanum catalyst supported on halloysite nanotubes (La/HNTs) was explored for the degradation of liquid epoxidized natural rubber (LENR) into low molecular weight LENR (lmw-LENR). The La/HNT catalyst was synthesized using a simple impregnation method and characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive X-ray (SEM–EDX), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). These techniques were employed to examine the physicochemical properties of the catalyst and to evaluate its performance in LENR degradation.
RESULT
The characterization revealed the presence of lanthanum hydroxide (La(OH)₃-n) species on the HNT surface. The La/HNTs effectively reduced the average molecular weight of LENR from 26 360 to 6961, corresponding to a 73.6% reduction under optimum conditions of 0.5 g catalyst loading at 150 °C for 4 h in a batch reactor. The degradation mechanism was attributed to hydroxide ions attacking the oxirane ring, leading to chain scission and the formation of shorter LENR chains. NMR and FTIR analyses confirmed the successful ring opening and cleavage of CC bonds, while the catalyst retained its structural integrity. Catalyst performance was strongly influenced by particle size, hydroxyl availability, and metal–support interactions.
Ling Yong Wong, Mohammed J. K. Bashir, Kumar Krishnan, Ling Shing Wong, Nor Faiza Abd Rahman, Khai Shin Chan
BACKGROUND
The escalating global water crisis underscores the urgent need for sustainable and efficient wastewater treatment technologies. This study investigates the use of nanosilica (SiO₂), extracted from rice husk—an abundant agricultural by-product—as a functional additive in polyethersulfone (PES) membranes. Membranes containing varying nanosilica loadings (0, 1, 3, and 5 wt.%) were fabricated via phase inversion and assessed for permeability and pollutant removal efficiency.
RESULTS
Incorporation of nanosilica markedly improved membrane performance, with the 5 wt.% PES–SiO₂ membrane exhibiting a pure water flux of 576.65 L m−2·h at 0.8 bar, approximately six times higher than pristine PES (96.85 L m−2·h). Pollutant removal was also significantly enhanced, achieving 91% turbidity reduction, 71% color removal, and 58% COD reduction. SEM analysis confirmed that nanosilica addition increased porosity and macrovoid formation, thereby improving hydrophilicity, permeability, and adsorption properties.
Dmitry Girenko, Bohdan Murashevych, Alexander Velichenko
BACKGROUND
Technologies and preparations that provide a fast and powerful microbicidal effect are vital for the prevention and treatment of infections. Active chlorine compounds, especially sodium hypochlorite (NaOCl), play an important role both as pharmaceuticals and as disinfectants. However, the stringent requirements for biomedical solutions do not allow the use of most traditional technologies for their synthesis. The paper describes the concept, architecture and individual components of an electrolyzer and its optimal operating parameters for obtaining high-purity NaOCl preparations.
RESULTS
The synthesis of target NaOCl solutions is expediently carried out by electrolysis of approx. 9.0 g L−1 NaCl solutions in original flow cells with a coaxial arrangement of electrodes. The optimal anode is a titanium tube with a catalytic RuO2–IrO2 coating. The cathode should be made of smooth titanium or of heat-treated platinized titanium. The initial electrolyte must be fed into the cell using a peristaltic pump. At a current load of 2 A and the use of two series-connected cells, the proposed technology ensures the production of 8.7 L h−1 of a solution containing 500 mg L−1 NaOCl and less than 1.0 mg L−1 NaClO3. An electrolyzer with three flow cells allows for the continuous production at 9.2 L h−1 of a 1000 mg L−1 NaOCl solution containing no more than 6 mg L−1 NaClO3.
Carlos A. Montenegro-Herrera, Mariana Manzoni Maroneze, María E. Rodríguez-Alegría, Alfredo Martinez
BACKGROUND
This study investigated the effects of different culture modes – autotrophy, mixotrophy and heterotrophy – on polyglucan accumulation and molecular weight distribution in four Galdieria sulphuraria strains. Understanding the impact of these culture modes helps optimize the production of reserve carbohydrates and modify their molecular properties for biotechnological applications.
RESULTS
The mixotrophic cultivation synergistically positively impacted microalgae growth, reserve polyglucan accumulation and productivity. Significant interaction effects between strain and culture mode were observed for all evaluated kinetic parameters, including biomass concentration (P = 9.06E−09), biomass productivity (P = 2.34E−06) and specific growth rate (P = 6.01E–15). The strain G. sulphuraria SAG 107.79 exhibited the highest glycogen accumulation, reaching 20.1% (w/w) under mixotrophic conditions, compared to 13.6% (w/w) and 5.1% (w/w) under heterotrophic and autotrophic modes, respectively. Culture mode also significantly affected the molecular weight distribution of polyglucans. Autotrophic cultures displayed a bimodal distribution, which may indicate the coexistence of α- and β-particle populations, while heterotrophic cultures showed a unimodal profile. The polydispersity index ranged from 1.65 to 9.18, indicating heterogeneity of the molecular weight of the polymer chains. Interestingly, under mixotrophic growth conditions, a high-molecular-weight polymer was obtained compared to the heterotrophic mode.
Enrico Mendes Saggioro, Bianca Miguel de Souza-Chaves, Morgana Bosio, Maria Emília Quinta-Ferreira, Rosa Quinta-Ferreira, Márcia Dezotti
BACKGROUND
This study focuses on utilizing the electrochemical oxidation (EO) process to eliminate psychoactive substances and aims to assess the impact of EO-treated water on the neuronal activity of rat hippocampus (specifically the CA3 region). The effectiveness of the ruthenium–iridium (Ru/Ir) EO process in degrading a mixture of carbamazepine and four benzodiazepines (alprazolam, clonazepam, diazepam and lorazepam) was evaluated in ultrapure (UP) water under various pH levels (ranging from 3 to 10), current densities (30–50 A m−2) and electrolyte concentrations (0.5 and 1.0 g L−1 NaCl). Ru/Ir were used as anode materials, with all pharmaceutical compounds initially present at a concentration of 100 μg L−1 in the mixture. Experiments were also conducted with surface water (SW) and municipal wastewater (MWW).
RESULTS
The optimal conditions, achieved at a current density of 50 A m−2, pH 7 and 1.0 g NaCl L−1, led to complete degradation of the compounds in 5 min. Higher removal efficiency were observed in UP water compared to real matrices, indicating greater competition for radicals in complex compositions. When using MWW, residual pharmaceuticals were detected even after 120 min of reaction. Neurotoxicity studies revealed varying impacts on reactive oxygen species production, with SW-treated solutions showing reversible effects and MWW-treated solutions displaying irreversible increases, highlighting the significance of Ru/Ir electrodes in EO processes.
Cobalt is a valuable metal whose total annual supply from recycling is projected to be 34 000 t by 2030, primarily from batteries. Supported liquid membrane (SLM) technology is emerging as a promising technology alternative to conventional hydrometallurgy for cobalt recovery.
RESULTS
This work featured the development of a novel physics-based computational fluid dynamics simulation for cobalt extraction from acetate-buffered synthetic Co–Ni solution in a hollow-fiber SLM system. The system involved cobalt and nickel, both at 0.167 mol L−1 initial concentration, sodium acetate buffer at 0.5 mol L−1 and pH adjusted to 5.85 with KOH or H2SO4. The process module had 57 m2 active surface area with a single fiber modeled as a cylindrical tube of 200 μm in diameter and 0.85 m in length in the Poiseuille flow regime with a total flow rate of 5.5 L min−1. At the fiber wall, an acidic organophosphorus SLM was present, where ion exchange between Co2+ and H+ occurred. Using experimental cobalt mass transfer rates dependent on Co2+concentration and the acetate pKa, simulation results within 5% of operational data were obtained for outlet Co2+concentration and pH. Parametric effects of feed flow rate and buffer concentration were explored to enhance system design and performance.
You Ma, Bo-Yu Liu, Tian-Yu Li, Hang Yang, Han Meng, Guo-Xiang Wang, Dong-Lin Li, Yu-Dong Chen, Wen-Ming Xie
BACKGROUND
Dissolved organic matter (DOM) in wastewater treatment systems plays a crucial role in the adsorption removal of antibiotics; however, this adsorption process remains underexplored. In this study, the effect of DOM components (protein, humic substances and polysaccharide) on the adsorption removal of trimethoprim (TMP) by activated sludge at environmentally relevant concentrations was investigated.
RESULTS
The humic substance had a positive effect on TMP adsorption, whose adsorption capacity was increased from 6.05 to 10.82 and 7.48 μg g−1 volatile suspended solids (P < 0.05), respectively, when 60 mg L−1 humic acid and fulvic acid were added. The negatively charged protein (30 mg L−1) had an inhibition effect on TMP adsorption process, in which the adsorption capacity was reduced by 24.1% (P < 0.05). However, the positively charged protein had a minor promotional effect. The polysaccharides (10 mg L−1) had a negligible effect on TMP adsorption.
Miljojka D. Mijailović, Vanja M. Tadić, Ivan B. Krstić, Jelena M. Avramović, Ana V. Veličković, Andjela T. Zahitović, Vlada B. Veljković, Miljana S. Krstić
Background
This study investigated the hydrodistillation process for extracting essential oil from sweet flag (Acorus calamus) rhizomes. The primary objectives were to evaluate the influence of the water-to-rhizome ratio on both the yield and chemical composition of the essential oil and to model the extraction kinetics.
Results
The water-to-rhizome ratio was found to significantly influence the yield of essential oil, with the highest yield (1.36 ±0.01%) obtained at a ratio of 11:1. However, variations in this ratio did not result in significant changes in the chemical composition of the oil. A first-order kinetic model was identified as the most suitable for describing the hydrodistillation process, offering simplicity and strong agreement with experimental data.
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