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The ability of ultrasound-catalyst hybrid system in degradation of HA, and survey the effective parameters in degradation is the objectives of the present study. The characteristics of the synthesised catalyst was investigated by SEM, XRD and UV-DRS. The performance of the system in pollutant removal was investigated using the OFAT (One Factor at a Time Method) method. The kinetics of the process, mechanism and the reusability of the catalyst were determined in optimised conditions. The results indicated that pH = 3, catalyst dosage = 400 mg/l, HA concentration = 5 mg/l have best efficiency (74%). Superoxide and hydroxyl radicals were considered as the main cause of HA degradation. Catalyst stability was investigated in 5 replicates and verified. The reduction in TOC obtained 45%. The overall results show that the ultrasound Fe–doped TiO2 hybrid system has partial promising performance in degradation of HA. [ABSTRACT FROM AUTHOR]

The aim of this study was to use tin oxide (SnO2) nanoparticle along with hydrogen peroxide (H2O2) and to evaluate their potential in removing direct red 81 (DR 81) dye from aqueous solution.This study was performed on a laboratory scale in a batch mode. To evaluate the structural properties of SnO2 nanoparticles, X-ray diffraction (XRD), and electron microscopy (SEM) images were used.According to BrunauerEmmettTeller (BET) analysis, the particle size is 10 nm. Laboratory results showed that the DR 81 removal efficiency by SnO2/H2O2 hybrid process reached 97.73% under the conditions including H2O2 concentration of 0.1 mmol/L, SnO2 concentration of 0.12 g, initial dye concentration of 25 mg/L, and pH of 3 after 60 min. DR 81 dye removal efficiency has a direct relationship with an increase in reaction time and SnO2 concentration while there is an inverse relationship between removal efficiency with the increase in pH, hydrogen peroxide concentration, and initial dye concentration.Considering the obtained results, the hydrogen peroxide activated by the SnO2 catalyst has a good ability for removal ofDR 81 dye, and this process can be used to remove DR 81 dye and other anionic dyes from wastewaters containing these pollutants. According to the results of the reaction rate, it can be concluded that the process follows the pseudo-second-order kinetics. [ABSTRACT FROM AUTHOR]

Dye is one of the most important environmental pollutants which threats human and environmental health. Due to the solubility and high stability of dye in water, incremental attention has been paid to their destruction and removal from industrial effluents. In this study, the efficacy of ZnO nanoparticles coated on natural zeolite (Zeo) as photocatalyst was evaluated to destroy the safranin dye in water solution under UV light. In order to determine the optimal conditions, the effect of dye concentration and solution pH were investigated. Field-emission scanning electron microscopy images show that ZnO is well situated on the Zeo surface and Fourier-transform infrared spectroscopy analysis confirmed the presence of Fe-ZSM5 Zeo and ZnO anatase phase in the synthesized photocatalyst. Optimal values of pH and the dye concentration for dye removal by synthesized UV/ZnO-Zeo photocatalyst were 9 and 100 mg/L, respectively. The maximum safranin dye removal (100%) in optimal conditions under UV light was obtained after 105 min. Also, the maximum adsorption capacity ZnO-Zeo catalyst for safranin was 26.35 mg/g. The removal efficiency reduced from 93% at run first to 32.15% at run fifth. In general, the results showed that the UV/ZnO-Zeo process can be used as an effective and efficient method in removing the safranin from aqueous environments. [ABSTRACT FROM AUTHOR]

In this study, Pseudomonas putida biomass was used to remove ceftriaxone from aqueous solutions. Biosorption was studied by living bacteria to achieve maximum biosorption. In order to investigate the shape, the biomass structure was analysed by SEM and FT-IR analyses. The effect of important parameters such as pH, contact time, adsorbent amount, and initial concentration of ceftriaxone solution, temperature, and the effect of ionic intensity on biosorption were studied. This study is an experimental study 250 ml Erlenmeyer was used as a batch reactor for the experiment. With increasing initial concentration, the removal efficiency increased. The best results were obtained at optimum pH = 7, adsorbent dose of 0.1 g, and initial ceftriaxone concentration of 50 mg/l after contact time of 120 minutes at the temperature of37 ∘ C and more than 50% of ceftriaxone was removed. Various isotherms including Langmuir and Freundlich were used to analyse equilibrium data at 37°C. The maximum adsorption capacity of this adsorbent was 109.5 mg/g. The results showed that the Freundlich isotherm is more consistent with the experimental data. Data fitting in the Freundlich adsorption isotherm model indicates non-uniformity of the absorbent surface. [ABSTRACT FROM AUTHOR]

These dyes have the potential for mutagenicity, carcinogenicity, and unwanted color on the one hand, and on the other hand, cause the production of toxic by-products in aqueous media. The aim of the present work is to synthesize scallop shell/iron oxide(II) nanocomposite and evaluate its efficiency in removing Direct red 81 (DR81) dye from aqueous solutions. Iron oxide nanoparticles were prepared by co-precipitation method and then the scallop was coated with iron oxide. The properties of synthesized nanocomposite were identified using Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, and X-ray diffraction. Effect of dye concentration (20–120 mg/L), contact time (0–240 min), adsorbent dosage (0.5–2.5 g), pH (3–11), and temperature (25°C–55°C) was investigated on decolorization efficiency of the process. Under optimal conditions (an initial DR81 concentration of 25 mg/L, pH of 3, adsorbent dose of 0.5 g, and contact time of 90), more than 98% of the dye was removed. The results showed that the efficiency decreases with increasing concentration. Moreover, by increasing the contact time and adsorbent dosage, dye adsorption percentage was enhanced. The maximum adsorption coefficient was 46.4 mg/g. In addition, Freundlich and Langmuir models were used to analyze the experimental isotherm data. The kinetic data of the adsorption process were in good agreement with the pseudo-secondorder kinetic model (0.995). The experimental data of the adsorption process followed the Langmuir model (R² = 0.91). The results show that Fe2 O3 nanoparticles coated with scallop shell as an environmentally friendly adsorbent can be effective in the adsorption of DR81. [ABSTRACT FROM AUTHOR]

Disinfection is one of the most important stages of water and wastewater treatment. Today, the use of photocatalytic processes by sunlight as a sustainable way of water disinfection has been noted. The purpose of this study was to remove coliform and fecal coliform from the effluent of a hospital sewage treatment plant using the solar/N-doped titanium dioxide (TiO2 ) process. In order to conduct the experiments, the raw samples (effluent of secondary sedimentation) were taken from the Ali Ibn Abi Talib hospital wastewater treatment plant in Zahedan City, Iran. N-doped TiO2 nanoparticles and the samples were poured into the reactor and then exposed to direct sunlight in summer. The results indicated that the photocatalytic process efficiency was enhanced by increasing reaction time and nanoparticles dosage. Furthermore, it was found that N-doped TiO2 nanoparticles and sunlight had a synergistic effect on the deactivation of coliform and fecal coliform. The number of coliforms and fecal coliforms bacteria cells decreased from 5 × 105 to 7 × 10³ MPN/100 mL and 4 × 10³ to 2 × 102 MPN/100 mL in the solar/N-doped TiO2 process after 150 min, respectively. It has been generally concluded that the solar/N-doped TiO2 process can effectively deactivate a wide range of real effluent microorganisms on a laboratory scale. [ABSTRACT FROM AUTHOR]

The amount of fluoride in drinking water sources is very important for public health. This study was conducted to evaluate the fluoride concentration in drinking water and compare the results with national and international standards, health risk assessment in non-cancerous diseases in East Azerbaijan province. This cross-sectional study was conducted in 20 large cities of East Azerbaijan province (West North of Iran) in warm (spring and summer) and cold (autumn and winter) seasons in 2017–2018.The results showed that the mean fluoride concentration in drinking water during cold and warm seasons was variable in the range of 0.19–0.65 and 0.18–0.62 mg/L, respectively. The Fluoride concentration in 80% of samples was lower than the standards. Also, the fluoride concentration in drinking water of studied cities was lower than calculated optimum concentration by Galagan and Vermillion equation. The estimated daily intake of fluoride (EDI) for infants, children, teenagers, and adults were 3.06, 2.15, 12 and 12.5 µg/kg/day, respectively. The hazard quotient (HQ) values for four age groups (infants, children, teenagers, and adults) for both seasons were lower than 1.Fluoridation and adjusting its concentrations in drinking water could be useful to compensate for its deficiency and prevent tooth decay. Based on the results, the non-carcinogenic risks of fluoride for the four exposed populations were below the safe limit. [ABSTRACT FROM AUTHOR]

TiO2 and Fe-doped TiO2 nanoparticles were synthesised by sol-gel method. To determine the properties of nanoparticles, scanning electron microscopy, X-ray diffraction and diffuse reflectance spectroscopy were used. The results of the analysis showed that the synthesised nanoparticles are almost uniform and agglomerated as well as the Fe-TiO2 band gap has decreased from 3.1 to 2.84 and the absorption spectrum has changed towards the visible region. The final concentration of 2,6-dichlorophenol and degradation products were measured with gas chromatography-flame ionisation detector and gas chromatography-mass spectrometry. The maximum efficiency and reaction rate constant of 2,6-dichlorophenol were determined at pH 4 and k0 = 2.11 × 10−2, initial concentration of 2,6-dichlorophenol 20 mg L−1 and k0 = 8.01*10−2, and nanoparticles dosage of 500 mgL−1 and k0 = 5.07*10−2 at 90 min time. The degradation reaction followed the first-order kinetic model. The efficiency of degradation and mineralisation of 2,6-dichlorophenol were in order of sonophotocatalytic > photocatalytic > sonocatalytic. [ABSTRACT FROM AUTHOR]

In this research, multi-walled carbon nanotubes-CoFe2 O4 magnetic (MWCNTs-CoFe2 O4 ) based-magnetic nanocomposite was used for removal of Remazol Brilliant Blue Reactive (RBBR) dye, which is one of the most widely used organic dyes in the textile industry. The various characterization methods such as Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller and vibrating sample magnetometer were used to confirm the formation of nanocomposite adsorbent and study its magnetic properties. The effective parameters on the removal process were time, adsorbent dose, dye concentration, pH and temperature. The optimal values of each of these parameters were determined as 40 min, 0.4 g, 20 mg/L, 3 and 298 K, respectively. The removal efficiency of RBBR dye in the presence of MWCNTs-CoFe2 O4 nanocomposite was 95% under optimal conditions. The maximum adsorption capacity (qmax) of MWCNTs-CoFe2 O4 for RBBR dye was 106.5 mg/g. The obtained experimental data were then analyzed with different isotherms such as Langmuir, Freundlich and Temkin and the results showed a very good agreement of the data with the Langmuir isotherm (R² = 0.9998). In addition, two quasi-first-order and quasi-second-order kinetic models studied the kinetic of the adsorption process. It was observed that the process follows the quasi-second-order kinetic. Finally, a thermodynamic study was carried out at four temperatures of 298, 308, 318 and 328 K to calculate the Gibbs free energy (ΔG) changes, enthalpy changes (ΔH) as well as entropy changes (ΔS). The calculated values for the mentioned thermodynamic parameters were –8.93 kJ/mol, –32.38 kJ/mol and 0.078 kJ/mol K, respectively. The results showed that dye adsorption is an exothermic, spontaneous process and is associated to a reduction in system irregularities. [ABSTRACT FROM AUTHOR]