Journal of Water Chemistry and Technology最新文献

In this study, the preparation of a new adsorbent, manganese dioxide-loaded volcanic rock (termed 3VRM), to improve the copper adsorption capacity of volcanic rocks (VRs) is reported. The effects of the loading ratio, 3VRM dosage, pH, and ionic strength on the Cu(II) adsorption capacity of 3VRM were determined. The samples were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). SEM analysis revealed that spherical nanoscale manganese dioxide with a plum pattern was attached to the surface of VR, effectively increasing the specific surface area and number of reactive sites on the adsorbent. The main components of volcanic rocks are schistose and foshagite; manganese dioxide also exists in an amorphous form. Manganese dioxide is stable in the form of Mn⁴⁺ before and after adsorption. The results revealed that 3VRM had the greatest effect on Cu(II) adsorption at a loading ratio of 3 : 1, dosage of 2.5 g/L, and pH of 4–6. The Cu(II) adsorption capacity of 3VRM was shown to fit well with the pseudo-first-order kinetic model and the Freundlich model. The reaction equilibrium time was 10 min, and the theoretical maximum adsorption amount reached 434.7 mg/g. The acidity of the solution had less effect on the 3VRM, so it could be used in a wide pH range of 3–6. Studies of ion exchange and surface complexation have shown that the material demonstrated high efficiency in removing copper ions. Owing to its good adsorption performance and high efficiency, it is expected to be used for copper-containing wastewater treatment in the future.

The present study investigated the adsorption efficiency of H₃PO₄ activated Chakhao rice husk activated carbon (CHAC) to remove sulphate ions (({text{SO}}_{4}^{{2 - }})) from an aqueous solution. The study’s finding highlighted 96.62% as the removal efficiency of sulphate ions using a dosage of 4 g/L of CHAC for a 60 s retention period. Moreover, the research findings illustrate that the highest removal of sulphate ions by adsorption occurs at the pH condition of 7. The study indicates that the presence of interfering anions such as phosphate, nitrate, chloride, fluoride, and bicarbonate notably impact the adsorption phenomenon of sulphate ions by CHAC. The study of various kinetic models, including the pseudo-first-order, pseudo-second-order, intra-particle diffusion, Bangham’s pore diffusion, and Elovich’s equation, illustrated the chemical kinetics of the adsorption phenomenon of CHAC. It was observed that the pseudo-second-order model demonstrated the most accurate fit for the kinetics studies with the r² value of 0.999. The experimental study also underwent analysis using various adsorption isotherm models, and the findings of the study highlight that the adsorption aligns more effectively with the Freundlich model, offering a superior fit for the equilibrium data.

Silver nanoparticles (AgNP) were prepared using the fresh leaf extract of Coleus amboinicus (CA) as both the capping and reducing agent through a microwave-assisted method. The phytosynthesized AgNP with CA (AgNP-CA) demonstrated highly selective optical and electrochemical sensing capabilities for mercuric ions. The AgNP-CA and complexation AgNP-CA with Hg²⁺ ions (AgNP-CA-Hg²⁺) were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared (FTIR), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), zeta potential, and dynamic light scattering (DLS) techniques. The effective complexation of AgNP-CA with Hg²⁺ ions resulted in visually observable colour changes, confirmed by UV-vis spectroscopy. The green-fabricated electrochemical AgNP-CA modified platinum electrode (AgNP-CA-Pt) sensor exhibited a limit of detection (LOD) of 0.8524 µM using the differential pulse voltammetry (DPV) method. The catalytic potential of AgNP-CA for the reduction of toxic organic dyes, Congo Red and Safranin, using NaBH₄ was also examined. The catalytic reductions were completed within a few minutes and followed a pseudo-first-order kinetics model. The linear relationship between catalyst concentration and reduction rates was experimentally determined. This eco-friendly approach to AgNP-CA synthesis and its applications is a useful tool for monitoring and managing environmental pollution.

The main consumer of water in the region is irrigated agriculture. Approximately 97% (93 800 million m³/year) are consumed by irrigated agriculture, whereas the other sectors, such as urban utilities and industry consume ~2700 million m³/year. Climatic changes towards warming will not only reduce the available water sources, but also increase the demand for them from agricultural crops, as higher temperatures increase the evaporation rate. It is expected that the total deficit of water in the two main rivers of Central Asia (Syr Darya and Amu Darya) in 2050 will attain 43 km³/year. Moreover, the monthly runoff regimes will essentially change. The total irrigated area of the Syr Darya River basin is 3.4 million ha, and the total use of the natural Syr Darya basin runoff is 30–150%. According to preliminary forecasts, the population in the Central Asia region is expected to grow by 30% to 2050 as compared to 2015 to attain >88 millions of people, so the areas of irrigated lands are planned to expand to solve the problem of food security in each country of this region. By 2025, the area of irrigated lands in the region must attain 11.8 million ha. This means that a lack of water will lead to the extended use of backwater for irrigation. This paper is devoted to studying the dynamics of the chemical composition of the Syr Darya River from the point of crossing the Tajikistan border to the point of passing to the neighboring Uzbekistan territory. Using the results of the chemical analyses of water samples, an attempt to estimate the utilization of water from the Syr Darya River for irrigation has been made. It has been established that, according to the principal indicators, just the content of adsorbed, soluble, and exchangeable sodium in the Syr Darya River fully meets the requirements to irrigation water.

One of the primary challenges faced by industrial enterprises involves the reuse of treated water. In paint and coating production, water becomes contaminated with various organic solvents, including butyl glycol, acetic acid, acetylacetone, and others. Efficient treatment and reintegration of this water into the technological process represent critical objectives. This study reports the results of single-stage liquid-phase wastewater treatment under the influence of a magnetic field with a magnetic induction of 20 mT, achieving purification efficiencies of 99.3% for butyl glycol, 99.1% for acetic acid, and 99.8% for acetylacetone. Isopropyl alcohol served as the extractant. The volumetric flow rates of wastewater and extractant were 3.0 and 0.3 dm³/h, respectively. The diameter of the extractor and the openings through which the extractant passes were d_extr = 0.03 m and d_op = 0.5 mm, respectively. Using a differential cell model, the concentrations of components in equilibrium phases along the height of the apparatus were calculated, along with the number of theoretical stages and the extractor height. The concentrations of components in the raffinate at the 20th cell were nearly identical to their initial concentrations, leading to the assumption of 20 theoretical stages. Given that the distance between theoretical stages is Δh = 0.05 m, the height of the extractor, with a diameter of 0.03 m, was calculated to be H_extr = 20 × 0.05 = 1.0 m. The degree of component extraction along the height of the extractor was also calculated. A zero-waste technology was proposed for treating wastewater contaminated with organic solvents to achieve maximum permissible concentrations (MPCs) using single-stage liquid–liquid extraction under the action of a magnetic field.

The development of new light sources (excimer, xenon, etc.) has enabled the use of vacuum radiation for the disinfection of natural and waste household and industrial water. Many papers are devoted to the modeling of photocatalytic oxidation systems, but they insufficiently highlight the effect of ultraviolet radiation on the processes occurring in the reactor when water structures in the surface water microlayer are activated. For this reason, the development of a model of calculating the effective radiation and energy effect parameters as a function from the absorbance of a treated liquid and the size of a reflector for surface irradiating water treatment systems is relevant. Just the vacuum ultraviolet quantity is a crucial factor in the synthesis of hydroxyl and peroxyl radicals immediately in water. In this paper, theoretical models and algorithms are proposed for the calculation of photocatalytic water treatment reactors with non-immersed radiation sources in the optimal UV radiation utilization regime. The applied oxidizers are known reagents, such as hydrogen peroxide, ozone, etc. Among all the reagents, ozone has the highest oxidation potential in water treatment. The possibilities of water treatment under the cumulative effect of photocatalytic ozone and UV radiation with the use of corresponding excimer lamps have been determined. For the system of irradiation with non-immersed light sources, it seems most promising to use photocatalytic ozone formed from oxygen under the influence of UV light radiation with wavelengths of 100–200 nm.

Eliminating total colour (TC) from municipal wastewater is vital to ensure public health and environmental protection. This study examines the effectiveness of using aluminum chloride coagulant (ACC), Moringa oleifera seed (MOS), and Lactobacillus plantarum strain (LPS) in the removal of TC from municipal wastewater (MW). The central composite design (CCD) is utilized to evaluate the efficiency of every procedure and clarify the interdependent aspects involved in the removal of TC. An R² value above 95% indicates that the created CCD model is highly reliable. The LPS, ACC, and MOS processes have operational costs of 6.4, 9.5, and 1.3 $/m³, correspondingly. Ultraviolet-visible spectrophotometry verifies the efficiency of every process in TC elimination. Additionally, 95% of organic matter is found in the sediment of MOS, making it an excellent organic fertilizer. Acute toxicity tests on Daphnia magna demonstrate significant activity, confirming that the proposed methods effectively contribute to sustainable development by lowering toxicity levels of influent. Optimum operating conditions of MOS were found to be a pH of 7, dose of 2.5 g/L and time of 25 min. Also, the work not only advances our understanding of effective TC removal strategies but also emphasizes the broader environmental and ecological benefits of the investigated processes.

Over the past two decades, many scientific journals have published a series of articles on environmental topics, which follow a similar pattern for studying adsorption on new materials. A review of more than 30 articles (as well as review practices), primarily focusing on the adsorption of synthetic organic compounds on new activated carbon materials, identifies the stages of scholarly research and highlights the main methodological and theoretical errors. These errors undermine the scientific value of these studies and reduce the experimental data presented within them to the status of scientific spam. The term “scholasticism” is used here in the sense of “pedantry,” “unified” nonessential research tasks, and excessive pondering over known or trivial matters. These issues point to gaps in the theoretical and practical training of young researchers. A typical feature of the scholastic approach is identified: instead of determining the conventional universal adsorption isotherm, the focus is on studying the influence of initial concentration, adsorbent weight, particle size, and contact time on adsorption efficiency—trends that are already well known to specialists. The epistemological significance and necessity of the stage of modeling experimental isotherms using both classical (Langmuir and Freundlich) and modern equations are critically evaluated. The paper presents a unique perspective on the role and objectives of modeling. The scholastic approach in kinetics relies on a formal description of rate laws, which predominantly ignore the physical nature of the adsorption of organic, especially aromatic, compounds, the hydrodynamics of flow, the fractional state of the adsorbent, the multistep nature of the process, and its limiting stage. The typical and characteristic inaccuracy of thermodynamic calculations in works exhibiting features of scholarly pedantry is highlighted, with the cause identified as the incorrect determination of the adsorption equilibrium constant, K_e. The paper gives specific methodological recommendations for environmental researchers, for whom adsorption-based water purification presents a new challenge, to avoid scholastic errors in their experimental endeavors and preserve the scientific value of their future work.

The presence of pollutants in water bodies compromises the aquatic ecosystem and public health. Crayfish waste is being discarded from the seafood market in large quantities annually. Crayfish shells can be valorized as biochar to remove water pollutants due to their availability and low cost. This paper review aims to highlight its preparation as an environmental-friendly adsorbent. Adsorption is a preferred process to remove various pollutants from water. The treatment methods and physicochemical properties of the derived biochar were highlighted, and the adsorption capacities of some model pollutants were compared and discussed. The calcium moieties and chitin in biochar aid in the adsorptive removal of target pollutants. Besides, the present challenges and future directions of crayfish shell biochar were presented to shed insight into practical applications in wastewater treatment.

This study investigated the degradation of a mixture of chlorophenol solution using various Advanced Oxidation Processes (AOPs). At different optimized conditions obtained for trichlorophenol, dichlorophenol, and monochlorophenol individually, additional optimization was performed for treating mixed chlorophenols (Mi-CPs). In photocatalysis degradation, rapid and complete removal of Mi-CPs was reported at pH 6.0, TiO₂ dose of 0.25 g/L, and H₂O₂ concentration of 10.0 mM within 270 min. In the case of photo-Fenton’s process, the complete removal was observed in 12 min at pH 3.0, Fe(II) 0.5 mM, and H₂O₂ 10.0 mM. Different AOPs integrated methods were also employed towards efficient removal. Solar-derived processes exhibited enhanced degradation rates. Assessment of electrical energy per unit order indicated sonication or UV-driven processes as energy-intensive processes over solar processes. For instance, solar-Fenton’s process resulted in complete chlorophenol removal in 8 min, whereas solar catalysis resulted in degradation of the toxicant within 315 min, albeit slightly longer than UV-driven catalysis. Hence, solar processes can be considered as an environmentally friendly approach for treating industrial wastewater. Furthermore, the toxicity analysis conducted for treated effluent using a macrophyte reported the disruption of plant tissues and ultimately plant death, signifying the presence of chemical species obstructing the plant metabolism and growth.