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Trifluralin is one of the most widely used herbicides, being accounted as the cause of cancer in human. In the present research, the UV/S2O82− and ZnO/UV processes’ efficiency in the removal of trifluralin was investigated. A lab scale equipped with a UV lamp was applied. The parameters were studied, including initial trifluralin concentration (0.4–1.2 mg/L), contact time (20–60 min), S2O82− concentration (20–60 μM), and ZnO concentration (50–150 mg/L). The remained trifluralin concentration was measured by HPLC. This study proved the trifluralin removal of 92.90 ± 1.6% and 87.91 ± 19.22% for UV/S2O82− and UV/ZnO processes in the best operation conditions (contact time of 60 min, the persulfate concentration of 40 μM, and the ZnO concentration of 100 mg/L). The optimal trifluraline concentrations were 1.2 mg/L and 0.6 mg/L for UV/S2O82− and UV/ZnO processes, respectively. In both processes, the removal efficiency of trifluralin increased significantly with increasing contact time. The findings exhibited that both processes UV/S2O82− and UV/ZnO followed the zero-order kinetic. The electrical energy consumed of UV/S2O82 and UV/ZnO was about 43.95 and 20.41 Kwh/kg, respectively. The results show that UV/S2O82− and ZnO/UV processes were appropriate as the effective treatment method for trifluralin removal. Therefore, it is proposed to study the performance of these processes as an environmentally friendly practice in full scale with real wastewater.

Nowadays, advanced oxidation processes, particularly photocatalyst process and catalytic ozonation by ZnO nanoparticles, are the most efficient method of eliminating pharmaceuticals. The purpose of this study was to compare the efficiency of ultraviolet/zinc oxide (UV/ZnO) and ozone/zinc oxide (O3/ZnO) techniques as advanced oxidation processes in the removal of trimethoprim (TMP) from aqueous solutions. The process consisted of 0.6 g/L of ozone (O3), pH = 7.5 ± 0.5, TMP with a concentration of 0.5–5 mg/L, ZnO with a dose of 50–500 mg/L, 5–30 min reaction time, and 30–180 min contact time with UV radiation (6 W, 256 nm) in a continuous reactor. The high removal efficiency was achieved after 25 minutes when ZnO is used in 1 mg/L TMP under an operational condition at pH 7.5. When the concentration of the pollutant increased from 0.5 to 1, the average removal efficiency increased from 78% to 94%, and then, it remained almost constant. An increase in the reaction time from 5 to 25 minutes will cause the average elimination to increase from 84% to 94%. The results showed that the efficiency of O3/ZnO process in the removal of TMP was 94%, while the removal efficiency of UV/ZnO process was 91%. The findings exhibited that the kinetic study followed the second-order kinetics, both processes. With regard to the results, the photocatalyst process and catalytic ozonation by ZnO nanoparticles can make acceptable levels for an efficient posttreatment. Finally, this combined system is proven to be a technically effective method for treating antibiotic contaminants.

Aniline with a benzene ring in its structure is a toxic, carcinogenic and mutagenic compound that causes many diseases in humans. Various methods have been developed to remove this pollutant from the environment among which the advanced oxidation has been successful in obtaining higher aniline removal efficiency. In this study, a UV light and Fe3O4 nano catalyst were used to remove aniline. In this study, the efficiency of aniline removal was studied as a dependent variable and aniline, hydrogen peroxide and iron nano catalyst concentrations, time and pH were investigated as independent variables. The concentration of aniline was measured by spectrophotometer. The optimization of the process was determined using the response surface method design and the central composite design model. Design Expert software was used to analyze the data. The results showed that the aniline removal efficiency decreased with increase in nano-catalyst concentration, hydrogen peroxide concentration and time and decreased with increasing pH and aniline concentration. To achieve maximum efficiency (78.1%), the optimal values for pH; initial concentration; time; nanoparticle content and H2O2 content were 3.2; 101 mg L-1; 50 min; 0.45 g L-1 and 31.08 mmol L-1. The results showed that the photo-Fenton process has a desirable ability to remove aniline from aqueous solution at pilot scale. Therefore, it was suggested to study the efficiency of this process as one of the clean and environmentally friendly methods at full scale on real wastewater.

Phenol and its derivatives constitute widespread water pollutants. They have been found to accelerate tumor formation, cancer, and mutation. In this paper, walnut shell residue has been used as a raw material in preparation of powder activated carbon by the method of chemical activation with zinc chloride for the adsorption of phenol from dilute aqueous solutions. The influence of the mass impregnation ratio (R = ZnCl2 /walnut shell) and physical activation by the CO2 stream on the physical and chemical properties of the prepared carbons was examined. The effects of main parameters such as contact time (t), initial phenol concentration (Co), and solution’s pH were studied on phenol adsorption. The maximum uptake of phenol at 25°C was 214 mg g–1 at pH near phenol pKa and Co = 1,000 mg L–1. All data were fitted well with Langmuir isotherm, but after CO2 modification, deviation from Langmuir shows that both physical and chemical adsorption occurred during adsorption. The kinetic data were fitted to different models such as pseudo-first-order, pseudo-second-order, and diffusion model. Pseudo-second-order model has been chosen as the best model. In overall, walnut shell shows excellent adaptive characteristics for the removal of phenol and appears as a very promising sorbent due to its high uptake capacity and to its low cost. © 2018 Desalination Publications

Copper, a heavy metal, causes environmental pollution through a variety of industrial processes in many countries. Adsorption is known as an effective and efficient way of removing heavy metals. The present study was conducted mainly to magnetize the carbon in wax bean waste with magnetite nanoparticles and use it as adsorbent to remove copper from aqueous solution. Carbon was obtained from wax beans waste and activated with magnetite nanoparticles. The characteristics of obtaining adsorbent were studied and analyzed by FE-SEM, BET, and FT-IR. In this study, the effect of pH, adsorbent dose, contact time and copper concentration on the efficiency of copper removal was investigated per full factorial design by the Design Expert Software. The concentration of copper was measured by atomic absorption spectrophotometer (Varian AA240). For statistical analysis of the experiment’s data, ANOVA and P-value were used. Copper initial concentration 100 mg/L, adsorbent dose 1 g/L, pH 7 and contact time 40 min were obtained as optimal conditions for copper removal. Investigation of the isotherms indicated that the experimental data of the process were correlated with Langmuir Model. The maximum capacity of copper adsorption of Langmuir Model was 49.75 mg/g. Findings indicated that at optimal conditions, the amount of copper adsorbed from synthetic wastewater and real wastewater was 99.73% and 63%, respectively. Therefore, this method is capable of removing copper effectively and could be used to remove this metal from industrial wastewaters. © 2018 Desalination Publications. All rights reserved.

In this study, removal of an antibiotic (SDZ) from wastewater using an advanced oxidation process of persulfate (PS) in the presence of iron sulfate (S2O8 –2/Fe+2) was investigated. The operational variables such as; the effect of pH, contact time, iron and PS ion concentrations and initial concentration of SDZ on the efficiency of SDZ removal was studied. High performance liquid chromatography (HPLC) was used for the analysis and monitoring of SDZ concentration. It was found that the highest rates of SDZ removal were found to be 95.83±1.342%, 87.15±0.929% and 69.09±0.848%, respectively, for initial SDZ concentration of 0.08, 0.2 and 0.4 mmol. The results showed that the S2O8 –2/Fe+2 system would be optimized by contact time of 60 min, pH 4 and iron to PS molar ratio of 1. Therefore, these findings would help to better apply the AOPs to remove recalcitrance pollutants such as SDZ from wastewater.