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Background & Objectives: 4-chlorophenolisone of the phenol derivatives that enters the environment from various sources. 4-chlrophenol ranks the primary pollutant agent. This study evaluated the efficiency and kinetics of photocatalytic degradation of 4-chlorophenol from aqueous solutions by sunlight and zinc oxide nanoparticles. Methods: This is an empirical study and Experiments were performed in the batch system. Determined dosage of ZnO nanoparticles was added to 4-chlorophenol solution (25-200ppm) and samples were allocated under the sunlight during midday hours in summer. Effects of parameters such as ZnO loading, pH, contact time and initial concentration of the polluter 4-chlrophenol were investigated. The remaining concentrations of 4-chlorophenol were analyzed using HPLC. Removal of total organic carbon was measured by TOC analyzer. Results: The results showed that removal efficiency of 4-chlorophenol was achieved 72%in presence of solar energy as means of energy source at both neutral and alkaline pH and catalyst dosage of 1.5grL-1. Efficiency increased as increasing pH and contact time. The photocatalytic degradation of 4-chlrophenol was best fitted with Langmuir–Hinshelwood model, and can be described by pseudo-first order kinetic. Conclusion: In general, 4-chlorophenols can be significantly degraded from aqueous solution by using sunlight as the energy source for the reaction and nano-sized zinc oxide as catalyst.

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Background & objectives: Millions of liters colored effluent is daily discharged into the environment by textile industries. These effluents are usually non-biodegradable and pose a serious problem to human and aquatic life. The aim of this study was to evaluate the degradation of acid black 1 using ZnO nanoparticle doped with the CuO as a catalyst in presence of the sunlight.

Methods: This study was an applied research in which ZnO:CuO nanoparticle was synthesized and its chemical properties was evaluated by X-ray diffraction (XRD). To evaluate the photocatalytic efficiency of synthesized nanoparticles, acid black 1 was prepared and the effects of parameters such as initial dye concentrations, photocatalyst dose, and pH on the photocatalytic process were studied. The results were analyzed using kenetic equations.

Result: The results showed that the synthesized particles are heterogeneous and have nanoscale size with no agglomeration. Dye degradation decreased with increasing the dye concentration and nanoparticle dose. It is observed that photocatalysis degradation rate of dye to increase with decreasing solution pH, because hydroxyl radicals are the dominant reactive oxidant under acidic pH. It was also found that the photocatalysis degradation to follow the Langmuir-Hinshelwood kinetic equation.

Conclusion: It is concluded that the synthesized nanoparticles have a high potential for dye degradation comparing to pure ZnO and can be used as an effective photocatalyst for degradation of dyes form colored effluents. 

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Background & objectives: Malachite green color has been extensively used in aquaculture industry around the world. The drainage of colored wastewater containing malachite green to aquatic ecosystems has created very serious risks for human health and the environment. The purpose of this study was to investigate the removal of green malachite from aqueous solutions using photocatalysis of titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles under the influence of ultraviolet (UV) radiation.
Methods: This study was carried out in laboratory scale and in discontinuous system using a photocatalysis process with radiation source of two UV lamps with a power consumption of 12 watts. Also, the impact of some factors including pH, nanoparticle content, malachite green concentration and contact time were investigated in green malachite removal from aqueous solutions.
Results: The results showed that the highest percentage of malachite green removal for titanium dioxide nanoparticle was 90.51% in malachite green concentration of 3.5 mg/l, pH 9, nanoparticle concentration of 5.2 mg/l and 180 minutes. Also, this value for zinc oxide nanoparticle was 91.23% in malachite green concentration of 14 mg/l, pH 9, nanoparticle concentration of 2.6 mg/l and 180 minutes.
Conclusion: According to the results of present study, the photocatalysis method under the influence of ultraviolet irradiation and two nanoparticles of titanium dioxide and zinc oxide, was a function of pH, contact time and the concentrations of malachite green and nanoparticles. It can be concluded that this method was a suitable method for removing malachite green from aqueous solutions.
 

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Background & objectives: Considering the effects of pollutants of industrial origin, such as heavy toxic metals-containing wastewater, on rivers and surface waters and the importance of their removal, in this study, the preparation, characterization and evaluation of zinc oxide nanophotocatalyst based on magnetic organic-metallic frameworks (ZnO@IL-mSiO₂@Cr-MIL-101), abbreviated as ZISM nanophotocatalysts, was evaluated in removing of lead (Pb²⁺) and arsenic (As³⁺) metals from aqueous samples.
Methods: This experimental study was performed using a ZnO-based nano-photocatalyst and a reactor consisting of an ultraviolet (UV) source and a reaction chamber for water samples contaminated with lead (Pb²⁺) and arsenic (As³⁺). To determine the removal efficiency of contaminants by ZISM nano-photocatalyst, the effect of various parameters including contaminant concentration, amount of nano-photocatalyst, pH and reaction time were investigated.
Results: The results showed that with increasing the amount of ZISM nano-photocatalyst and pH, the removal of lead and arsenic increased. The maximum removal of Pb²⁺ and As³⁺ was obtained 99.8 and 98.3, in initial concentration of 5 mg/L, nano-photocatalyst dose of 250 mg/L, pH =8 mg/L and reaction time of 60 min.
Conclusions: According to the results, the ZISM nano-photocatalyst emerged as an efficient and recyclable nano-photocatalyst, which was a potential and environmentally friendly process for the removal of toxic heavy metals as hazardous water pollutants. This photocatalyst showed good recyclability in 5 consecutive periods.