Competition between chalcogen bond and halogen bond interactions in YOX4:NH3 (Y = S, Se; X = F, Cl, Br) complexes: An ab initio investigation

Using ab initio calculations, the geometries, interaction energies and bonding properties of chalcogen bond and halogen bond interactions between YOX4 (Y = S, Se; X = F, Cl, Br) and NH3 molecules are studied. These binary complexes are formed through the interaction of a positive electrostatic potential region (σ-hole) on the YOX4 with the negative region in the NH3. The ab initio calculations are carried out at the MP2/aug-cc-pVTZ level, through analysis of molecular electrostatic potentials, quantum theory of atoms in molecules and natural bond orbital methods. Our results indicate that even though the chalcogen and halogen bonds are mainly dominated by electrostatic effects, but the polarization and dispersion effects also make important contributions to the total interaction energy of these complexes. The examination of interaction energies suggests that the chalcogen bond is always favored over the halogen bond for all of the binary YOX4:NH3 complexes. © 2016 Springer Science+Business Media New Yor

Photocatalytic degradation and mineralization of diazinon in aqueous solution using nano-TiO2(Degussa, P25): kinetic and statistical analysis

Abstract: In this study, photocatalytic degradation of diazinon was investigated using nano-TiO2, Degussa P25, as a photocatalyst and the effects of some operational parameters such as aeration, pH, photocatalyst concentration, and the irradiation time were also examined. Dispersive liquid-liquid microextraction technique was used to extract and pre-concentration of residual diazinon from the liquid samples and all experiments were carried out by gas chromatography. Amount of degradation and mineralization were determined by gas chromatograph with flame ionization detector (GC/FID) and COD measurements, respectively. The optimum condition for degradation of diazinon has been obtained in the pH 6, [nano-TiO2] = 0.2 g/L, and [time] = 120 min. In the optimal condition the removal efficiency of diazinon and COD were 99.64 and 65%, respectively. The results have shown that the nano-TiO2, aeration and time of reaction have a positive effect on photocatalytic degradation of diazinon and COD removal. Statistical analysis showed that the maximum removal of diazinon and COD were due to UV irradiation (71%, 41%), exposure time (16%, 39%), aeration (7%, 4%), and increased concentration of nano-TiO2 (0.4%, 2%), respectively; and the kinetics of photodegradation were found to follow a first-order kinetic model and the constant rate, at optimal condition, was 0.038 (min−1). © 2014 Balaban Desalination Publications. All rights reserved

Heterogeneous catalytic ozonation of 2, 4-dinitrophenol in aqueous solution by magnetic carbonaceous nanocomposite: catalytic activity and mechanism

Herein, the catalytic properties of a carbonaceous nanocomposite in the catalytic ozonation process (COP) of 2, 4-dinitrophenol (2, 4-DNP) were investigated and the results were compared with those obtained from single ozonation process (SOP). Magnetic carbonaceous nanocomposite, as a novel catalyst, was applied to optimize the condition for the removal of 2, 4-DNP in the COP, and the influential parameters such as pH, catalyst dosage, addition of radical scavengers, and durability were all evaluated. The results showed that the degradation efficiency of 2, 4-DNP and COD in the COP (98.2, 92) was higher compared to the SOP (75, 61) and the highest catalytic potential was achieved at an optimal pH of 6. The first-order modeling demonstrated that the reactions were dependent on the concentration of the catalyst, with the kinetic constants varying from 0.022 (1/min) in the SOP to 1.377 (1/min) in the COP at the catalyst dosage of 4 g/L and the optimum concentration of catalyst (2 g/L). The addition of radical scavenger noticeably diminished the removal efficiency of 2, 4-DNP in the SOP from 75 down to 54, while the corresponding values for the COP dropped from 98.2 to 93. Furthermore, a negligible reduction in the catalytic properties of the catalyst was observed (~5) after five-time reuse. The results also revealed that the applied method is effectively suitable for the removal of 2, 4-DNP contaminant from industrial wastewaters. © 2015 Balaban Desalination Publications. All rights reserved

Survey of parasitic contamination of sewage sludges in northern Iran

The use of sewage sludge as fertilizer in agriculture is a convenient and economic solution, but it is essential to monitor presence of parasitic contamination. This study investigated parasites in sewage sludge of wastewater treatment plant in Gorgan, Iran. This descriptive-analytical study was performed on 18 sewage sludge samples collected from wastewater treatment plant of Gorgan within 6 months with three repeatitions per month. The samples were analyzed in the laboratory of School of Public Health at Golestan University of Medical Sciences. Analysis of parasites was done using Bailenger method of counting parasites in chamber of McMaster slides with volume of 0.3 ml. The results showed that majority of parasite eggs in the sewage sludge was related to nematodes. The dominant nematode eggs detected were related to Ancylostoma duodenale, Necator americanus and Enterobious vermicolaris. However, no parasite was found in dried sewage sludge. Considering the amount of parasite eggs in the returned sludge, it is necessary to modify the treatment process. However, it is permissible to use dried sewage sludge as agricultural fertilizer.Keywords: Parasite eggs, Protozoa, Sewage sludge, Ira

Description of BTEX concentrations with wind roses in Tehran city: the study of monitoring, GIS-zoning maps and risk assessment

In the present study, the emission of BTEX compounds has been investigated in a one-year period (2016�2017) in Tehran city. According to, 26 sampling stations were selected in different parts of the city and had been sampled in four seasons of year to determine the concentration of BTEX as well as other meteorological parameters such as temperature, humidity and wind speed. Spatial distribution analysis of BTEX was introduced by using the Inverse Distance Weighting (IDW) method in Arc GIS 10.3. Also, to determine the carcinogenic and non-carcinogenic risk of target compounds, Monte Carlo simulation was used. The results showed that the annual mean of benzene, toluene, ethylbenzene, m-xylene and o-xylene were 30.08 ± 21.97, 54.17 ± 40.29, 25.81 ± 15.21, 27.83 ± 19.1 and 23.16 ± 12.28 μg/m3, respectively. According to the result, the maximum and minimum concentrations of BTEX were in the center and north of the city, respectively. Temporally, the maximum value of BTEX was 232.61 ± 123.93 µg/m3 in the autumn and the minimum value was 57.88 ± 24.93 µg/m3 in the spring. The result obtains from the inhalation lifetime cancer risk (LTCR) indicative the carcinogenic potential of benzene. Noncarcinogenic risk index, namely the hazard quotient (HQ) for all BTEX compound except benzene concentration in the autumn (1.55), were lower than 1 degree so they were not harmful to human health. © 2021 Taylor & Francis Group, LLC

Discoloration and mineralization of a textile azo dye using a hybrid UV/O3/SBR process

Most synthetic dyes are toxic and hardly biodegradable compounds that enter the environment mainly through the discharged of non-treated textile industry effluents. The present study investigated the removal of the textile monoazo dye Reactive Red 198 (RR-198) from aqueous solutions using the ultraviolet light and ozonation alone and in combination (i.e., UV/O3) followed by a Sequencing Batch Reactor (SBR). The pH (5 � pH � 9) and dye initial concentration (50�300 mg/L) parameters were optimized in the ozonation process at reaction time of 0�60 min. Then, TOC removal and dye discoloration percentage was compared with the O3, UV and O3/UV processes. In order to compare the performance of the SBR in dye discoloration of RR-198 and TOC removal, four types of effluent, including Raw dye, O3-pretreated dye, UV-treated dye and UV/O3-pretreated dye were separately treated in the SBR system. In the ozonation process, by increasing the pH and reducing the initial dye concentration increased the discoloration percentage. The highest dye discoloration percentage and TOC removal obtained in the hybrid UV/O3/SBR process. Combining biological systems and Advanced Oxidation Processes is an appropriate option for the decomposition of resistant pollutants and increasing the biodegradability of these compounds and is applicable in the water and wastewater industry. © 2021, The Author(s)

Data on wastewater treatment plant by using wetland method, Babol, Iran

Date in this paper highlights the applications of constructed horizontal surface flow (HF-CW) wetland with two different local plants (Louis latifoila and Phragmites -australis (Cav.) Trin) at the wastewater treatment plant in Babol city. This system was designed as an advanced treatment unit in field scale after the treatment plant. Parameters such as Total Dissolved Solid (TDS), Total Suspended Solid (TSS), Turbidity, Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), were investigated. The result shows that treatment efficiency increases with the passage of time. The efficiency of Phragmites planted setups in open environment was fairly good for all studied parameters (28.6 of TDS, 94.4 for TSS, 79.8 for turbidity, 93.7 for BOD and 82.6 for COD). The efficiency of the latifoila set up was also good, but lower than that of Phragmites (26.5 of TDS, 76.9 for TSS, 71.5 for turbidity, 79.1 for BOD and 68.8 for COD). In brief, the obtained dates show that using local plants in (HF-CW) wetland not only effectively reduces various contaminants from the effluent of the wastewater according to Effluent Guideline regulations (WHO & EPA), but it is also a cost- effective and environmentally friendly method. Also, it was calculated that in full scale operation time (1 day) and a depth (0.3 m), 8 ha of wetland was needed. © 2018 The Author

Catalytic degradation of diclofenac from aqueous solutions using peroxymonosulfate activated by magnetic MWCNTs-CoFe3O4 nanoparticles

CoFe3O4 nanoparticles supported on multi-walled carbon nanotubes (MWCNTs-CoFe3O4) were synthesized by the co-precipitation method as a novel catalyst for degradation of diclofenac (DCF). The comparative experiments indicated that MWCNTs-CoFe3O4 has a better catalytic activity in degradation of DCF and activation of peroxymonosulfate (PMS) compared to other catalytic systems. This can be attributed to the interaction of MWCNTs with CoFe3O4 in accelerating the absorption process and activating the PMS (Ea = 22.93 kJ mol-1). The removal efficiencies of DCF and total organic carbon (TOC) were 99.04 and 50.11, under optimum conditions, e.g., pH of 7, PMS dosage of 4 mM, DCF concentration of 30 mg L-1, catalyst dosage of 500 mg L-1, and reaction time of 120 min. The oxidation of DCF was fitted by the pseudo-first-order kinetic model and the constant rate was increased by increasing the pH, temperature, dosage of PMS and catalyst. The production of reactive species was studied using scavengers such as TBA and ethanol and the results showed that sulfate radical is the reactive species responsible for the degradation of DCF. The MWCNTs-CoFe3O4 catalyst showed high stability and reusability based on five successful repeated reactions, X-ray diffraction and energy dispersive X-ray spectroscopy analysis. Based on the intermediates detected by gas chromatography-mass spectrometry (GC-MS), the possible pathways for DCF catalytic oxidation were proposed. The results explained that the PMS/MWCNTs-CoFe3O4 system is a promising method for treating DCF solution due to high efficiency, good reusability of catalyst and greater PMS activation. © 2019 The Royal Society of Chemistry

Optimisation of COD removal from the olive oil mill wastewater by combined electrocoagulation and peroxone process: modelling and determination of kinetic coefficients

The olive oil extraction industry is one of the most extensive industries, especially in the Mediterranean region. The wastewater produced in this industry contains high concentrations of organic pollutants, resistant and toxic compounds that, if not treated, can threaten the health of the environment. In the present study, the optimisation of the combined process of electrocoagulation and peroxone using central composite design of the response surface methodology with the help of Design-Expert V.11 The parameters of current density (0.06�0.73 A dm�2) and reaction time (5�45 min) in the process of electrocoagulation and the parameters of hydrogen peroxide concentration (4�12 ml) and reaction time (10�90 minutes) in the peroxone process were investigated on the COD removal efficiency. The design results showed that the quadratic model was significant for both processes and was determined as the selected model. The optimal conditions determined by the software in the process of electrocoagulation were 0.5 A dm�2 and 34 minutes and in the peroxone process, concentration of hydrogen peroxide and the time were obtained 12 ml and 62 minutes, respectively. In these conditions, the COD removal efficiency of the processes was determined 79.8 and 52.8, respectively. Under optimal conditions, in peroxone process ozone consumption was reduced to 0.88 mg per mg of removed COD. Also, according to the results of Pseudo-first-order kinetics, constant rate increases with increasing of hydrogen peroxide concentration. The results obtained in this study were confirmed the application of electrocoagulation process along with advanced oxidation of proxone for effective treatment of effluents of this industry and similar industries. © 2021 Informa UK Limited, trading as Taylor & Francis Group

Heavy metal contamination in the effluent and sludges of wastewater treatment plant in Gorgan, Iran

Background and purpose: Environmental pollution by heavy metals and their transfer to soil and crops are a growing global problem. This study aimed to measure the concentrations of heavy metals in wastewater and sludge wastewater treatment plant in Gorgan, Iran. Materials and methods: In this cross-sectional study, 176 samples of effluent, and returned and dried sludges were analyzed in wastewater treatment plant in Gorgan, during six months in 2016. The concentration of Pb, Cd, Ni, and Cr were determined using polarography (Metrohm797 AV) and furnace atomic adsorption spectroscopy (AA 240 Varian Co.) in the laboratory of Health Faculty in Golestan University of Medical Sciences. Results: The average concentrations of Pb, Cd, Ni, and Cr in the effluent were 0.105 ± 0.06, 0.0089 ± 0.008, 0.095 ± 0.108, and 0.102 ± 0.175 mg/L, respectively. The concentrations of Pb, Cd, Ni, and Cr in returned sludge were 323.48 ± 217.65, 2.44 ± 3.3, 354.14 ± 322.79, and 388.53 ± 252.59 mg1/kg of dry weight, respectively. Also, in dried sludge, the average concentrations of lead, cadmium, nickel, and chromium were 58.48±2.67, N.D, 30.31±1.98, and 506.25±813.81 mg/kg of dry weight, respectively. Conclusion: The concentrations of heavy metals in wastewater effluent and dried sludge, except in returned sludge, were below the standards. Due to long-term use of effluents, necessity of treatment of other parameters, and the effect of bioaccumulation of metals in sludge, caution should be taken for their agricultural application. Also, because of importance of this type of contaminants in soil and food products, continuous monitoring by water companies is highly necessary. © 2017, Mazandaran University of Medical Sciences. All rights reserved