Journal of Water Chemistry and Technology最新文献

In this study, PS/UV-C and PMS/UV-C processes were used for the removal of pollutants from domestic and industrial wastewater. The effects of initial oxidant concentration, initial pH value and reaction time on COD and TOC removal efficiencies were determined by laboratory-scale, batch experimental studies. In the results of the study, the highest removal efficiency was obtained with PS/UV-C process at 25 mM oxidant concentration, pH 7 and at the end of the reaction time of 60 min, and the COD and TOC removal efficiencies were found to be 90.5 and 90.8%, respectively. In the study, unit and specific electricity consumptions were also calculated in order to compare the costs of PS/UV-C and PMS/UV-C processes. The optimum removal efficiency for PS/UV-C was obtained at pH 7 and 25 mM PS concentration and at 60 min of reaction time. Unit electricity consumption (E_EO) values for COD and TOC parameters were calculated as 39.1 and 38.4 kWh/m³, respectively, and specific electricity consumption (E_EM) as 80.5 and 181.8 kWh/kg, respectively. As a result of the kinetic studies obtained f or COD removal in both PS/UV-C and PMS/UV-C applications, it was determined that the reaction was compatible with the second-order kinetic model. PS/UV-C reaction rate was obtained 2 times higher than PMS/UV-C. It has been determined that PS/UV-C process is a more suitable process in terms of removing COD and TOC compared to PMS/UVC in the treatment of this urban wastewater.

The disposal of persistent organic pollutants (POPs) in water streams continues to be a challenge, where textile and pharmaceutical industries are major contributors to this global challenge. This review paper focuses on chemical and physical modification processes in place to successfully increase the performance of poly(ether)sulfone polymeric membranes with a much more improved hydrophilicity for the removal of POPs. This work is carried out for the effective and efficient removal of persistent organic pollutants in wastewater treatment plants. Poly(ether)sulfone remains the most preferred polymer in the synthesis and application of nano-filtration (NF) and ultra-filtration (UF) membranes. Using specific composition values, the phase inversion process is used for the distribution of additives or particles unto the membrane scaffold in order to fabricate the PES polymer. This tends to influence the polymer’s ideal chemical, mechanical and thermal stability. However, an observed high hydrophobicity is its main shortcoming, which frequently leads to the increased membrane fouling and flux. The performance of PES can however be improved by fabrication with suitable additives, and this automatically increases the hydrophilicity of the synthesized membrane. An approach in the PES modification differs in processes, (1) graft polymerization, where nano and micro particles are chemically imparted on the membrane scaffold; (2) plasma treatment, which uses chemical radicals and electronically excited particles, or gas under atmospheric pressure; and (3) physical pre-adsorption of hydrophilic components onto the membrane scaffold. Also, the bulk modification process was discussed further in this work as it seeks to bring a new approach in the modification process of PES membrane. This applies modification of the membrane materials before membrane synthesis by incorporating hydrophilic additives in the membrane matrix solution during the synthesis. Sulfonation and carboxylation techniques are discussed at the core of their mechanisms. In conclusion, polymer blending results in separation efficiencies being increased significantly and also resulting in improved surface characteristics.

Vibrio fischeri bioluminescence inhibition assay (VFBIA) is known for bacterial contamination measurement in water and food. This system is a type of quorum sensing identification that is an intracellular cumulative active mechanism. This experiment aims to increase the light emission of bioluminescent bacteria (V. fischeri and Vibrio sp. Persian 1 strains) using magnetic nanoparticles (MNPs). To this end, different concentrations of magnetic nanoparticles were added to the artificial seawater medium (ASW). Standard strains (V. fischeri) and Iranian native strain (Vibrio sp. Persian 1) were cultured in magnetic nanoparticles containing media. In the following, nanoparticles’ features, including concentration, size, and surface modification, were optimized for sufficient bacterial growth. Mostly, nanoparticles with surface modifications using arginine and lysine (MNPs@Arg, MNPs@Lys) were selected accordingly, and the growth and light emission of bioluminescent bacteria in the presence of various factors of nanoparticles were analyzed. The results showed that ASW with 200 μg/L MNP@Lys and 150 μg/L MNP@Arg were suitable for increasing the growth rate and light emission of V. fischeri and Vibrio sp. Persian 1, respectively. V. fischeri and Vibrio sp. Persian 1 in the presence of a particular concentration of nanoparticles (MNP@Lys and MNP@Arg) in a medium grow faster and emit more rapid light than in the absence of nanoparticles. Finally, the results show that the iron nanoparticles do not have any bactericidal features. Also, they have a complex of ingredients that could improve the bacteria’s functions and growth.

Water contamination is primarily caused by effluent from the textile sector. The highly toxic and non-biodegradable nature of pollutants in the effluent makes it challenging to remove these compounds, which therefore poses harm to the environment. An effective technology, biosorption, may be a viable method for mineralizing hazardous contaminants from wastewater. Water hyacinth is one of several inexpensive adsorbents that is a fast-growing, widely accessible plant with high removal rates. A catalyst called cetyl trimethyl ammonium bromide was used to activate the biosorbent. By using the central composite design of response surface methodology and the adsorbate as a synthetic wastewater, ideal conditions of significant parameters, including temperature, pH, sorbent dosage, and contact duration were obtained. The real textile effluent was subjected to the ideal conditions and adsorption efficiency of 92.88 ± 0.5% was attained. Chemical oxygen demand of the effluent was reduced by 50% after the biosorption. The attribution of functional groups in the adsorbent to different wavenumbers was made evident through the Fourier-transform Infrared Spectroscopy analysis, and the morphology and porous structure of the biosorbent were shown through scanning electron microscopy. In order to potentially act as an adsorbent for the biosorption of pollutants from textile effluents, surface-modified water hyacinth root powder could be employed.

A detailed description of test organisms from a set for the integrated bioassay of the quality of natural and drinking water is given. Their choice is substantiated, as well as the sensitivity to various classes of toxic substances with respect to specific individuals, and the advantages and disadvantages for the bioassay of water with a low level of contamination are considered. The biological substantiation of the selected animal and plant test organisms with various trophic levels is given along with accounting for their selective sensitivity to toxic substances of various origins. The possibilities of using tissue cells of test organisms to determine cytotoxicity and genotoxicity when changing the physicochemical parameters of the aquatic environment are considered. The prospects for extrapolating the results of the integrated bioassay to the human body with long-term consumption of low-quality drinking water are discussed. A formula for calculating the amount of intake of a chemical substance into the human body is proposed. It is emphasized that the degree of biological pollution of the aquatic environment cannot be adequately assessed by bioassay methods.

This paper presents a test method for determining the total hardness in natural and drinking waters using an indicator solution for test titration. The developed method offers a rapid and efficient procedure for assessing the total hardness across a wide range of water bodies. The relative standard deviation of a single result in determining the overall hardness does not exceed 10%. The lower limit for determining the total hardness is 1°dH/5 cm³ of the sample solution.

The effectiveness of low-cost biosorbent Blepharispermum hirtum for the removal of Zn(II) ions from aqueous solution was examined. To assess the impact of solution pH and temperature on biosorption capability, batch biosorption tests were conducted. The optimum conditions for biosorption were discovered at pH 6.0, 0.5 g/L of biomass, and 15 min of equilibrium duration. The biosorption data was well represented by Langmuir model with correlation coefficient of 0.9981 followed by Freundlich, Temkin and Dubinin--Radushkevich isotherms with the correlation coefficients of 0.9834, 0.9812 and 0.8790 respectively at a solution temperature of 303 K. According to the Langmuir isotherm model, the maximal adsorption capacities (q_max) for Zn(II) was 27.66 mg/g. The Fourier-transform infrared spectrometer (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to carry out the characterization studies of biosorbent Blepharispermum hirtum. Discrete aggregates developed on the surface of the biosorbent because of interaction with metal ions. Either electrostatic attraction or a complexation mechanism held the metal ions to the biosorbents’ active sites.

The electroplating industry generates wastewater and solid waste with diverse compositions and numerous components. Different chemical compositions and low concentrations of heavy metals both in solid wastes and in waste and washing waters make it necessary to develop treatment technologies for almost every type of wastewater. In this study, we investigated the extraction of nickel compounds from solid sludge by treatment with 0.1 M sulfuric acid at an acid-to-sludge ratio of 5 : 1, followed by electrodialysis preconcentration and electroreduction to recover nickel from the resulting solution at an electrode. The concentrations of Cu, Zn, and Fe impurity ions do not exceed the maximum permissible values and do not affect the kinetics or productivity of the nickel electrodeposition process. The current yield of nickel at the cathode reaches 96%. Additionally, the introduction of buffer substances enhanced the stability of nickel deposition at the cathode.

The photodegradation of 4-NP is extensively studied by ternary nanocomposite of N-TiO₂ and Ag₃PO₄ co-grafted on GO sheets. The photodegradation of 4-NP follows pseudo-first order kinetics, which can be fitted by Langmuir–Hinshelwood model. The kinetic study confirms that photodegradation is influenced by catalyst dose, initial 4-NP concentration and solution pH. The highest photocatalytic activity of 68% is achieved with N-TiO₂/Ag₃PO₄@GO(0.6) using a catalyst dose of 1.5 g L^–1 for initial 4-NP concentration of 10 mg L^–1 at pH 7.5 up to 150 min of visible-light illumination. The enhanced visible light absorption, substantial separation of photogenerated e^––h⁺ pair, improved surface area and faster interfacial charge separation between the three components in the ternary composite favoured the efficient photodegradation of 4-NP.

A novel pyrrolidinium based-task-specific ionic liquid was successfully synthesized and characterized to specific complexation of Cr(VI) ions in aqueous media. In fact, by the use of a powerful in-situ solvent formation microextraction technique, trace levels of Cr(VI) ions in some real water and wastewater samples were determined. The microextraction of Cr(VI) ions was carried out by complexation of Cr⁶⁺ ions with ionic liquid of (1-(2-(quinolin-8-yloxy)ethyl)pyrrolidinium chloride) abbreviated as [QPyr][Cl]. A complexation between [QPyr][Cl] as carrier with Cr(VI) ions as analyte in aqueous solution system was done to transfer of analyte to the non-aqueous phase and finally the determination of Cr(VI) ions in aqueous solution (before and after the above procedure) was performed by atomic absorption spectrometry. Analytical parameters affecting the microextraction system were optimized by using the response surface methodology (RSM). The resulting equation was used to draw response surface plots for prediction of the extractive behavior of the Cr(VI) ions and to find the optimal extraction conditions. At optimized conditions, the calibration curve was linear in the range 50–750 ng/L; the limit of detection of 5.5 ng/L and the relative standard deviation of 2.9% for seven replicate determinations were obtained. As a result, the technique was successfully being applied for the determination of Cr(VI) in some water and wastewater samples with satisfactory recoveries.