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The aim of the present study was to synthesis Ni-doped TiO2 nanoparticles (NPs) in order to evaluate their effectiveness in photocatalytic degradation of formaldehyde in the aqueous phase. The Ni-doped TiO2 NPs were synthesised using a mild hydrothermal method. They were then immobilized on glass plates by the calcination method. Characterisation of Ni-doped TiO2 NPs was also carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The SEM images showed the uniform distribution of as-synthesised NPs on the surface of glass plates, with multidimensional crystalline structures. The results indicated that increasing the dopant weight ratio to 0.7% enhanced the photocatalytic degradation efficiency of formaldehyde; however, a further increase in the dopant weight ratio reduced the process efficacy. According to the results, increasing the initial pH from acidic and neutral to alkaline conditions decreased the efficacy of the process. Furthermore, the results showed that increasing the amount of nanocatalyst and decreasing the initial concentration of formaldehyde favoured the photocatalytic degradation of formaldehyde. [ABSTRACT FROM AUTHOR]

Groundwater is the only source of high quality water for human consumption in most parts of the world; however, it can be easily contaminated by domestic, industrial, and agricultural wastes such as fertilisers and pesticides. The main objective of the present research was to study the photocatalytic removal of 2,4-Dichlorophenoxyacetic acid pesticide (2,4-D) from aqueous media. This was a laboratory scale study in which the zinc oxide nanoparticles were doped with 0.5, 1, and 2 molar percent of tungsten oxide. The nanoparticles synthesised were characterised using powder XRD, SEM, FTIR, and UV-Vis Spectroscopy analyses. During the photodegradation of 2,4-D, the operational parameters studied were pH, nanoparticles dosage, initial pesticide concentration, light intensity, contact time, and the mineralisation trend of organic matter. It was found that the doped nanoparticles had a smaller band gap energy, which confirms the effect of doping. The percentage of the dopant can affect the pesticide removal efficiency. The optimal pH value obtained was 7. In addition, the process efficiency, increased from 27% to 78% with increasing UV light intensity from 172 to 505 W/m2 respectively. Moreover, it was found that, with increasing light intensity, contact time and nanoparticle concentration all caused the pesticide removal efficiency to be increased too. In addition, the increase of the pesticide concentration would cause a reduction in the process removal efficiency. This study indicated that the photocatalytic process using tungsten doped zinc oxide nanoparticles can remove the 2,4-D pesticide by around 80% from the aquatic environment. [ABSTRACT FROM AUTHOR]

In this study, photocatalysis of phenol was studied using Cd-ZnO nanorods, which were synthesized by a hydrothermal method. The Cd-ZnO photocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and Fourier transform infrared (FT-IR) and UV-Vis spectroscopy. XRD patterns exhibit diffraction peaks indexed to the hexagonal wurtzite structures with the P63mc space group. SEM images showed that the average size of the Cd-ZnO nanorods was about 90 nm. Moreover, the nanorods were not agglomerated and were well-dispersed in the aqueous medium. FT-IR analysis confirmed that a surface modifier (n-butylamine) did not add any functional groups onto the Cd-ZnO nanorods. The dopant used in this study showed reduction of the bandgap energy between valence and conduction of the photocatalyst. In addition, effect of various operational parameters including type of photocatalyst, pH, initial concentration of phenol, amount of photocatalyst, and irradiation time on the photocatalytic degradation of phenol has been investigated. The highest phenol removal was achieved using 1% Cd-ZnO for 20 mg/l phenol at pH 7, 3 g/l photocatalyst, 120 min contact time, and 0.01 mole H2O2. [ABSTRACT FROM AUTHOR]

In this study, magnetic chitosan/bone char/Fe3O4 nanocomposite (MCB-Fe3O4 nanocomposite) was prepared and utilized as an adsorbent for the removal of Cr(VI) from aqueous environments. The effects of influencing parameters such as initial concentration of Cr(VI), adsorbent dose, initial pH, mixing rate, salinity and the existing of competing organic compounds on the adsorption of Cr(VI) were investigated. According to the obtained results, the adsorption process followed the pseudo-first-order kinetic model and Langmuir adsorption isotherm model. Decreasing initial pH from 11 to 2 resulted in increasing the removal efficiency (%) from 24.94 to 88.60%, respectively. Also, the efficiency (%) of Cr(VI) removal increased from 33.73 to 98.81% when the dose of adsorbent rose from 0.25 to 4.0 g/L, respectively. The presence of ethanol and humic acid in solution resulted in decreasing the removal efficiency (%) of Cr(VI) ions. [ABSTRACT FROM AUTHOR]

Long-term intake of water with high content of trihalomethanes (THMs) such as chloroform (CHCl3) is hazardous for human health. Some studies have shown that clinical effects of THMs in drinking water may be yet observed to doses lower to standard limit. In our study, we performed a meta-analysis to assess both the mean concentration of CHCl3in Iranian drinking water and the relative health effects by long-term exposure to safe dose of CHCl3in the male and female age groups and in female categories. We applied the Target Hazard Quotient (THQ) for the evaluation of the noncarcinogenic risk of CHCl3. Meta-analysis (14 studies) showed that the average concentration of CHCl3was 24 µg/l (95%CI:18.1–30.1 µg/l), I2 = 99.88,p < .001. Minimum and maximum concentrations of CHCl3was related to Mashhad (3.5 ± 0.5 µg/l) and Mazandaran (57.3 ± 13.1 µg/l) province, respectively. The average concentration of CHCl3in the all studied provinces was lower than USEPA (70 µg/l) and national standard limits (200 µg/l). The minimum and maximum THQ was related to <0.5 and 15–19 years age groups in both the males and females. The rank order of THQ in the female categories was females aging 15–44 (0.074)> non-pregnant and non-lactating females age 4–15 (0.071) > pregnant (0.071) > lactating (0.043). The THQ in the females was higher than males, non-significantly (p >.05). Except Mazandaran province, in other provinces both males and females, for all age groups, were not exposed to significant risks by non-carcinogenic exposure of CHCl3in drinking water (THQ <1). [ABSTRACT FROM AUTHOR]

Although, several benefits can be offered by the consumption of marine products, the heavy metals bioaccumulation inside of their body can put the health of consumers at a high level of risk. In this context, however, the Persian Gulf contentedly is polluted by waste water, solid waste and petroleum activities residues, due to an increasing trend in consumption of fished aquatic organisms such as fish and shrimp, the safety of marine products is a source of concern. The current review was established in order tracing the metals concentrations in the muscle of fished shrimps from the Persian Gulf as well as conducting the health risk assessment. The reviewed literature was based on the internal and external databases. According to the results of 23 studies, the maximum and minimum heavy metals concentrations were determined as Zn (8.56 ± 34.68 μg/g) and Hg (0.08 ± 0.04 μg/g), respectively. Moreover, the heavy metal levels in the 32.5% of studies were higher than premiered limit by the WHO/FDA guidelines. Based on the calculated median for heavy metals concentrations, Total target hazard quotient (TTHQ) for the adults and children were reported as 0.466 and 0.311, respectively. The order of the concentration of the heavy metals can be demonstrated as following: Co > As > Cd > Pb > Cu > Zn > Mn > Ni > Hg > Cr. Considering the results of risk assessment, no potential human health risk for the consumer's shrimps of the Persian Gulf was observed. Research highlights Maximum and minimum of heavy metals concentrations in the shrimps were determined as Zn and Hg, respectively, in the Bushehr, Khuzestan, Bandar Abbas, Qeshm Island, Kuwait and Qatar.Total target hazard quotient for the adults and children were less than 1 value.Overall, potential health risk of heavy metals does not threaten consumer’s heath. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) is the second cereal consumed in Iran. Many studies have been carried out in Iran about the contamination of rice by environmental pollutants such as heavy metals. The aim of present study was: • to systematically review about Arsenic (As), Chromium (Cr), Lead (Pb), Cadmium (Cd) and Nickel (Ni) concentrations in cultivated rice in Iran and; • to estimate the non-carcinogenic risk for age and sex groups. We applied the target hazard quotient (THQ) and total target hazard quotient (TTHQ) to evaluation of the non-carcinogenic risk. International and Iranian databases were searched from January 2008 to October 2016. Data obtained from 27 articles showed that minimum and maximum concentrations of heavy metals were As (0.05 ± 0.09 μg/g dry weight) and Ni (0.83 ± 0.04 μg/g dry weight), respectively. The rank order of heavy metals based on THQ was As > Cr > Pb > Cd > Ni. Also the rank order of consumers rice based on TTHQ were rural females (0.49) > urban females (0.461) > rural males (0.455) > urban males (0.41). Minimum and maximum of TTHQ was related to 35–44 and 15–24 years age groups both males and females, respectively. Since THQ and TTHQ were either lower than 1 value, therefore, consumers were not exposed to carcinogenic risk by consumption of rice cultivated in Iran. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles were prepared through the chemical precipitation method and immobilized on glass plates. The effects of initial pH, UV lamp power, glass surface area, and initial humic substances (HS) concentration on the photocatalysis of HS were studied. Acidic conditions favoured the photocatalysis of HS. The degradation efficiency of HS was enhanced by increasing the UV lamp power and glass surface area. According to the results of total organic carbon (TOC) analysis, a mineralization efficiency of 59.3% was obtained within a reaction time of 120 min in comparison with the removal efficiency (%) of UV254, which was found to be 83.3%. [ABSTRACT FROM PUBLISHER]

Malachite green (MG) is one of the most used dyes in textile industries. The aim of this research work was to degrade MG, a model dye, using nickel-doped TiO2nanocatalysts. Nickel-doped TiO2nanocatalysts were fabricated under mild hydrothermal conditions (p = autogenous,T = 100°C, andt = 12 h). Nickel oxide andn-butylamine were used as dopant and surface modifier, respectively. The samples dried were characterized using powder X-ray diffraction, zeta potential, SEM, and electron diffraction X-ray analysis. The batch experiments of MG degradation were performed under UV light and sunlight irradiation. The effect of operational parameters including nanocatalyst dosage, pH, contact time, initial concentration of dye solution, and light source were investigated systematically. It was found that nickel-doped TiO2nanocatalysts had better solar degradation efficiency compared with bare TiO2under both UV light and sunlight irradiation. The optimum solar degradation efficiency for MG dye solution was achieved at pH 8, nanocatalyst dosage = 1.2 g/l, contact time = 120 min, and initial dye concentration = 250 mg/l. [ABSTRACT FROM PUBLISHER]

In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2 %) observed using 1.5 % Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation. [ABSTRACT FROM AUTHOR]

Background: In this research, the removal of natural organic matter from aqueous solutions using advanced oxidation processes (UV/H2O2 was evaluated. Therefore, the response surface methodology and Box-Behnken design matrix were employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as initial concentration of H2O2 (100-180 mg/L), pH (3-11), time (10-30 min) and initial total organic carbon (TOC) concentration (4-10 mg/L) were studied. Results: Analysis of variance (ANOVA), revealed a good agreement between experimental data and proposed quadratic polynomial model (R² = 0.98). Experimental results showed that with increasing H2O2 concentration, time and decreasing in initial TOC concentration, TOC removal efficiency was increased. Neutral and nearly acidic pH values also improved the TOC removal. Accordingly, the TOC removal efficiency of 78.02% in terms of the independent variables including H2O2 concentration (100 mg/L), pH (6.12), time (22.42 min) and initial TOC concentration (4 mg/L) were optimized. Further confirmation tests under optimal conditions showed a 76.50% of TOC removal and confirmed that the model is accordance with the experiments. In addition TOC removal for natural water based on response surface methodology optimum condition was 62.15%. Conclusions: This study showed that response surface methodology based on Box-Behnken method is a useful tool for optimizing the operating parameters for TOC removal using UV/H2O2 process. [ABSTRACT FROM AUTHOR]

The degradation of two commercially available dyestuffs (C.I. Reactive Black 5 and C.I. Disperse Orange 25) by ultraviolet radiation (UV), ultrasonic irradiation (US), UV/HO and US/HO processes was investigated in a laboratory-scale batch photoreactor equipped with a 55 W immersed-type low-pressure mercury vapor lamp and a sonoreactor with low frequency (42 kHz) plate type transducer at 170 W of acoustic power. The toxicity was also evaluated in acute toxicity studies using Daphnia magna. Results showed that color removal efficiencies by US and US/HO processes were negligible for both dyes. Almost complete disappearance of Reactive Black 5 (97.9%) in UV/HO process was possible after 5 min of irradiation. The maximum color removal efficiency of Disperse Orange 25 after 10 min of irradiation, however, was only 9.2% and reached a maximum value of 41% after 120 min of irradiation. Pseudo-first order kinetics with respect to dyestuffs concentrations was found to fit all the experimental data. The results clearly showed that both dyes examined were toxic to D. magna and resulted in quite low LC values. [ABSTRACT FROM AUTHOR]

Humic acid is one of the predominant organic substances in both surface and ground waters, creating an unpleasant taste and color in water. It is one of the most important precursors of disinfection by-products. Magnetite nanoparticles were synthesized through the chemical precipitation method. Removal of humic acid from aqueous solutions using magnetite nanoparticles was compared with commercial hematite nanoparticles by changing the effective parameters including pH, nanoparticle dosage, humic acid concentration, reaction time, and temperature. Moreover, the adsorption isotherms were evaluated using Langmuir and Freundlich models. The results showed that by increasing pH from 3 to 11, the efficiency of both nanoparticles decreased. The highest performance of nanoparticles was achieved at pH = 3, nanoparticles dosage of 0.25 g/L, and contact time of 90 min. The isotherm graphs and linear regression coefficient values indicated that adsorption using hematite and magnetite fits the Langmuir models. The kinetic study showed that the adsorption using both hematite and magnetite follows second-order-kinetics. Both synthesized magnetite and commercial hematite show good performance for the removal of humic acid. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. [ABSTRACT FROM AUTHOR]

Simple synthesized Nano-sized ZnO powder in the absence of high-temperature activation treatments was studied to act as sono-catalyst. Effects of six operational parameters such as initial solution pH (pH0), initial concentration of dye stuff (C0), additional dose of nano-sized ZnO powder (DSC), ultrasound (US) irradiation frequency (FrSC), US irradiation power (PSC), and treatment time (tSC) were examined. Synthetic wastewater containing Reactive Red 198 (RR198) was used as the sample model. Combined design of experiments was done and experiments were conducted according to protocols. The experimental data were collected in a laboratory-scaled batch reactor equipped with ultrasonic bath cleaner as the ultrasonic source. The measured CR% ranging from 0.8 to 100 and EnC (wh) from 0.3 to 13.6 gained under given conditions. The data used for modeling were used in two more common models in this type of studies: Multiple linear regression (MLR) and artificial neural network (ANN). The ANN models obviously outperformed MLR models. Finally, Multi-objective optimization of CR% and EnC was carried out using genetic algorithm (GA) over the outperformed ANN models. The optimization procedure causes non-dominated optimal points which give an insight of the optimal operating conditions. [ABSTRACT FROM AUTHOR]