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The work deals with the removal of two dyes, namely methylene blue (MB) and methyl orange (MO), from polluted water by adsorption onto CuO nanoparticles synthesized with a green synthesis procedure, starting from plant resources. Adsorption isotherms are determined at different temperatures aiming at investigating the adsorption mechanisms of the two dyes. The experimental results indicate that, for both MB and MO, the adsorption capacity increases with increasing temperature, with slight differences in the case of MO. Comparatively, the CuO nanoparticles show a higher MB adsorption capacity with respect to MO.A modelling analysis is carried out with a multilayer model derived from statistical physics, selected among a group of models, each hypothesizing a different number of adsorbed molecules layers. The analysis of model parameters allows determining that the adsorbate molecules exhibit a non-parallel orientation on the surface of biosynthesized CuO nanoparticles and each functional group of the adsorbent binds multiple molecules, simultaneously.The model also allows determining the number of dye molecule layers formed on adsorbent surface, in all the cases resulting higher than three, also confirming the effect of temperature on the maximum adsorption capacity.Specifically, the total number of dye layers formed on biosynthesized CuO nanoparticles surface exhibited a range of 4.17–4.55 for MB dye and of 3.01–3.51 for MO dye.Finally, the adsorption energies reveal that adsorption likely involves physical forces (all resulting all below 22 kJ/mol), i.e. hydrogen bonding and van der Waals forces. The adsorption energies for the interactions between dye molecules are lower than those calculated for the interactions between the dye molecules and the adsorbent surface.

The current study comprehensively investigates the adsorption behavior of chromium (Cr(III)) in wastewater using Algerian kaolinite clay. The structural and textural properties of the kaolinite clay are extensively characterized through a range of analytical methods, including XRD, FTIR, SEM-EDS, XPS, laser granulometry, N2 adsorption isotherm, and TGA–DTA. The point of zero charge and zeta potential are also assessed. Chromium adsorption reached equilibrium within five minutes, achieving a maximum removal rate of 99% at pH 5. Adsorption equilibrium is modeled using the Langmuir, Freundlich, Temkin, Elovich, and Dubinin–Radushkevitch equations, with the Langmuir isotherm accurately describing the adsorption process and yielding a maximum adsorption capacity of 8.422 mg/g for Cr(III). Thermodynamic parameters suggest the spontaneous and endothermic nature of Cr(III) sorption, with an activation energy of 26.665 kJ/mol, indicating the importance of diffusion in the sorption process. Furthermore, advanced DFT computations, including COSMO-RS, molecular orbitals, IGM, RDG, and QTAIM analyses, are conducted to elucidate the nature of adsorption, revealing strong binding interactions between Cr(III) ions and the kaolinite surface. The integration of theoretical and experimental data not only enhances the understanding of Cr(III) removal using kaolinite but also demonstrates the effectiveness of this clay adsorbent for wastewater treatment. Furthermore, this study highlights the synergistic application of empirical research and computational modeling in elucidating complex adsorption processes.

AbstractThis study aimed to enhance the production of the intracellular L-asparaginase bacterial enzyme, which is known to impede the growth of cancer cells, by optimizing the culture conditions. In the present study, we exploited the ability of a new Actinomycete strain isolated from a food byproduct, wheat bran, to produce the desired enzyme. Streptomyces paulus CA01 was identified following morphological, biochemical, and molecular testing, and its total L-asparaginase activity was evaluated using ADS agar. Intracellular L-asparaginase activity was measured on the same medium using the well-diffusion method and was quantified by Nesslerization. A Box-Behnken design was employed to optimize the production of the enzyme by analyzing the effect of three factors: temperature, L-Asparagine concentration and glucose concentration. The ADS base medium, which was previously optimized and consisted of starch, K2HPO4, and MgSO4, was also included in the analysis. The optimal conditions for intracellular L-asparaginase production were temperature of 27.5 °C, L-Asparagine concentration of 1.19%, glucose concentration of 0.26% and ADS base medium composition, with which we achieved an incrase in enzymatic activity from 3.20 IU/mL to 8.39 IU/mL. This study indicates that Algerian wheat bran is a potential source of Streptomyces paulus CA01, which produces the bacterial intracellular L-asparaginase enzyme and also opens up prospects for the exploitation of agricultural by-products as sources of interesting micro-organisms. Despite the complex process of cell lysis required for its production, intracellular L-asparaginase is important and depends on culture conditions, making its optimization and increased yield feasible.

In this work, we propose a study of the SO2 mass-transfer rate in an absorption process based on the use of an aqueous solution of ammonia (NH3), which reacts with SO2 to give ammonium sulfite according to follow overall reaction SO2 + 2NH3 + H2O ? (NH4)2SO3. An experimental and modelling study is carried out to define the thermodynamic and kinetic aspects of the ammonia-based Flue Gas Desulfurization (FGD) process. A dataset of SO2 solubility in aqueous ammonia solutions was estimated by simulations in ASPEN PLUS using an equilibrium model based on data provided in the relevant literature. The Enhancement factors (EL) for the SO2 ammonia-based absorption are determined under the explored experimental conditions: different gas and liquid flow rates, and feed molar NH3(aq)/SO2(g) ratios, varying both concentrations of ammonia in the liquid and sulfur dioxide in the gas streams.

This study investigates the efficacy of adsorbents from locally sourced olive waste—encompassing olive skins, leaves, and pits, recovered from the initial centrifugation of olives (OWP)—and a composite with sodium alginate (OWPSA) for the removal of Cu2+ ions from synthetic wastewater. Experimental analyses conducted at room temperature, with an initial Cu2+ concentration of 50 mg/L and a solid/liquid ratio of 1 g/L, showed that the removal efficiencies were approximately 79.54% and 94.54% for OWP and OWPSA, respectively, highlighting the positive impact of alginate on adsorption capacity. Utilizing statistical physics isotherm models, particularly the single-layer model coupled to real gas (SLMRG), allowed us to robustly fit the experimental data, providing insights into the adsorption mechanisms. Thermodynamic parameters affirmed the spontaneity and endothermic nature of the processes. Adsorption kinetics were interpreted effectively using the pseudo-second-order (PSO) model. Molecular modeling investigations, including the conductor-like screening model for real solvents (COSMO-RS), density functional theory (DFT), and atom-in-molecule (AIM) analysis, unveiled intricate molecular interactions among the adsorbent components—cellulose, hemicellulose, lignin, and alginate—and the pollutant Cu2+, confirming their physically interactive nature. These findings emphasize the synergistic application of experimental and theoretical approaches, providing a comprehensive understanding of copper adsorption dynamics at the molecular level. This methodology holds promise for unraveling intricate processes across various adsorbent materials in wastewater treatment applications.

Emerging pollutants are a widespread environmental concern, andadsorption represents one of the choices available for the removal of suchcompounds from polluted waters. However, the set‐up of a new adsorption system requiresthe experimental determination of adsorption isotherms and their thoroughmodelling, for the sake of a convenient optimization. In this work, the Campomanesia guazumifolia biomass is adopted as precursor for the synthesis of anew adsorbent and then tested for the adsorption of KTP and 2,4‐D. Theadsorption performances of this biomass are significantly improved through atreatment with sulfuric acid, which allows obtaining higher removal efficiency ofthe target organic molecules. The experimental isotherms are measured at 298 – 328 K and pH 2. An ETAM model is employed for amodeling analysis of the experimental data, for the comprehension of theoccurring adsorption mechanism. Results demonstrated that adsorption of KTP isendothermic and occurs in multilayer with a multimolecular process, in whichthe molecular aggregation can be predicted. On the contrary, the adsorption of 2,4‐D on this functionalized biomass is exothermic. The adsorption energiesresulted to be < 40 kJ mol−1, indicating that physical adsorption forces are involved inthe removal of these organic molecules. [ABSTRACT FROM AUTHOR]

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end in Annaba Bay (Algeria) in the Mediterranean Sea, with a significant level of contamination, all the potential sources should be identified. In this work, this task is conducted by a multivariate analysis. Liquid–liquid extraction and gas chromatography/mass spectrometry (GC–MS) methods were applied to quantify seven PCB congeners, usually taken as indicators of contamination. The sum of the PCB concentrations in the sediments ranged from 1 to 6.4 μg/kg dw (dry weight) and up to 0.027 μg/L in waters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for the multivariate analysis, indicating that the main sources of PCB emissions in the bay are urban/domestic and agricultural/industrial. The outfalls that mostly contribute to the pollution of the gulf are the Boujemaâ wadi, followed by the Seybouse wadi, and finally by the Fertial cluster and more precisely the annex basin of the plant. Although referring to a specific site of local importance, the work aims to present a procedure and a methodological analysis that can be potentially applicable to further case studies all over the world.

The photoactivated periodate (UV/IO4−) process is used to investigate the degradation of acid orange 10 (AO10) dye. The photodecomposition of periodate ions produces highly reactive radicals (i.e., •OH, IO3•, and IO4•) that accelerate dye degradation. Increasing the initial concentration of periodate to 3 mM enhances the dye removal rate, but over 3 mM periodate, the degradation rate slows down. On the contrary, increasing initial dye concentrations reduces the degradation performance. pH is the most critical factor in AO10 breakdown. Salts slow down the degradation of the dye. However, UV/IO4− is more efficient in distilled water than natural water. Even at low concentrations, surfactants may affect the dye’s decomposition rate. The addition of sucrose reduced the breakdown of AO10. Although tertbutanol is a very effective •OH radical scavenger, it does not affect the dye breakdown even at the highest concentrations. Accordingly, the AO10 degradation is a non-•OH pathway route. According to retrieved data, the photoactivated periodate method eliminated 56.5 and 60.5% of the initial COD after 60 and 120 min of treatment time; therefore, it can be concluded that the UV/IO4− system may treat effluents, especially those containing textile dyes.