Initial TOC Research Articles

GEOCHEMICAL ANALYSES OF EOCENE OILS IN DEEPLY BURIED SANDSTONE RESERVOIRS IN THE DONGYING DEPRESSION, BOHAI BAY BASIN, NE CHINA

We report the results of organic geochemical analyses of 19 crude oil samples from reservoir sandstones in the 4th Member of the Eocene Shahejie Formation from wells in the Minfeng Sag, Dongying Depression, Bohai Bay Basin (NE China). In addition, 42 Shahejie Formation core samples of dark‐coloured mudstones, including 28 extracts, were analysed. Geochemical data included Rock‐Eval measurements, gas chromatography, GC‐MS and diamondoid analyses.Maceral analyses showed that mudstones in the 4th Member of the Shahejie Formation (“Es4”) contain Types I and II1 kerogen. The member can be divided into upper (Es4s) and lower (Es4x) intervals. Oil‐prone Es4s rock samples have good to excellent hydrocarbon‐generating potential based on calculated initial TOC values; Rock‐Eval Tmax values indicate that they are sufficiently mature for hydrocarbon generation. Analytical results suggest that both Es4s and Es4x mudrocks are potential source rocks for oils produced at fields in the Minfeng Sag.Analysed crude oils from the Minfeng Sag were classified into three genetic groups. Group I oils are mature to highly mature and have undergone a moderate degree of thermal cracking. They are characterized by a low β‐carotane/nC25 ratio and C30 4‐methylsterane index (4MI); high values of oleanane index (oleanane /C30‐hopane), C27 diasterane/C27 regular sterane (C27Dia/C27), regular sterane/17α hopane and gammacerane/C30 hopane (G/H); and medium pristane/phytane ratios (Pr/Ph). This suggests that Group I oils are mostly derived from source rocks in the upper part of the Es4x unit which are interbedded with evaporites. Group II oils are mature and have high 4MI and Pr/Ph ratios, low oleanane index, regular sterane/17α hopane and C27Dia/C27 ratios, and mediumβ‐carotane/nC25 and G/H. These features are similar to those of Es4s source rocks, indicating their genetic correlation. Group III oils show the lowest maturity and highβ‐carotane/nC25 and regular sterane/17α hopane, and low oleanane index, Pr/Ph and 4MI. Previously‐published data indicates that oils similar to those in Group III were mainly sourced by Es4s mudstones.

Activated carbon/g-C3N4 /H2O2 system with enhanced photocatalytic activity for Rhodamine-B degradation under the visible light

In this study, activated carbon/g-C3N4 photocatalyst (BC/CN) was successfully prepared by a facile calcination method from activated carbons derived from banana peels and urea. As a result, the morphology of BC/CN consisted of the activated carbons highly dispersed on the g-C3N4 matrix. The advanced oxidation process of BC/CN and hydogen peroxide exhibits a better catalytic activity towards Rhdamine-B degradation in visible-light region than those of the pristine g-C3N4 or BC with hydrogen peroxide. The grafting of activated carbon to g-C3N4 enhanced the electron transfer efficiency and suppressed the photoinduced electron-hole recombination. Initial TOC was about 650 mg/L; however, it decreased by 93% to 60 mg/L after 60 min treating. After four cycles of experiments, the catalyst BC/CN still presented high activity for the degradation of RhB. In addition, all N-deethylation intermediates and several small molecular products were separated and identified by LC/MS method. Based on the analytical results, a possible mechanism of photocatalytic degradation was proposed. This work demonstrates a facile and efficient approach to improving the performance of g-C3N4-based catalysts.

High-order splitting finite element methods for the subdiffusion equation with limited smoothing property

In contrast with the diffusion equation which smoothens the initial data to C ∞ C^\infty for t > 0 t>0 (away from the corners/edges of the domain), the subdiffusion equation only exhibits limited spatial regularity. As a result, one generally cannot expect high-order accuracy in space in solving the subdiffusion equation with nonsmooth initial data. In this paper, a new splitting of the solution is constructed for high-order finite element approximations to the subdiffusion equation with nonsmooth initial data. The method is constructed by splitting the solution into two parts, i.e., a time-dependent smooth part and a time-independent nonsmooth part, and then approximating the two parts via different strategies. The time-dependent smooth part is approximated by using high-order finite element method in space and convolution quadrature in time, while the steady nonsmooth part could be approximated by using smaller mesh size or other methods that could yield high-order accuracy. Several examples are presented to show how to accurately approximate the steady nonsmooth part, including piecewise smooth initial data, Dirac–Delta point initial data, and Dirac measure concentrated on an interface. The argument could be directly extended to subdiffusion equations with nonsmooth source data. Extensive numerical experiments are presented to support the theoretical analysis and to illustrate the performance of the proposed high-order splitting finite element methods.

Experimental and theoretical insights into advanced removal of the refractory cibacron green H3G dye by UV/chlorine innovative oxidation process

The discharge of highly persistent Cibacron Green H3G (CG-H3G) dye by textile factories poses a significant threat to both environmental and human health. In this study, the UV/chlorine advanced oxidation process was successfully used to degrade and mineralize this dye. The synergism resulted from coupling 254 nm irradiation UV and low chlorine dosage was assessed at various solution pH (5–10) and liquid temperature (up to 50 °C) for a range of chlorine dosage (50–200 µM). In only 5 min, 85 and 100 % of CG-H3G (20 mg/L) were eliminated with high synergy indexes of 4.34 and 6.3 for 100 and 200 µM of dissolved chlorine, respectively. Besides, 45 and 72 % of the initial TOC were mineralized after 30 and 60 min of photoirradiation with 100 µM chlorine. The synergistic treatment was more efficient as chlorine dosage increased (in the range 10–200 µM), and solution pH and temperature decreased (pH range: 5–10, temperature range: 20–50 °C). Cl2− and OH/Cl radicals were identified as the key oxidants degrading CG-H3G with contributions of 35 % for {OH + Cl}, 65 % for Cl2− at 100 µM of chlorine, and 25 % for {OH + Cl}, 75 % for Cl2− at 200 µM of chlorine. The contribution of Cl2− increased by 10 % chlorine dosage increase from 100 to 200 µM, whereas the contribution of {OH + Cl} decreased by 10 %. Finally, the different project’s results were analyzed by adopting a simulation approach, where the concentration profiles of the different reactive species generated during chlorine photo-activation (specifically at steady state) was related to the degradation outcomes. This analysis provides an easier understanding of the degradation mechanism that occurs in the UV/chlorine process when applied to treat refractory textile effluents in deionized water.

Nanoplastics removal from spiked laundry wastewater using electro-peroxidation process

Microplastics and nanoplastics (NPs) in laundry wastewater (LWW) are major sources of plastic particles in wastewater treatment plants. Unlike microplastics, almost no information exists in the literature on the degradation of NPs in LWW. In this work, the degradation of NPs in commercial LWW by the electro-peroxidation process is investigated. The obtained results demonstrated that already existing ions in LWW such as Cl− contribute to faster degradation of NPs and a complete removal could be obtained as fast as 40 min. In addition, three-dimensional excitation and emission matrix fluorescence analysis was performed, which revealed humic acid-like, aromatic proteins-like, and fulvic acid-like compounds could be oxidized after 20, 40, and 60 min of treatment respectively. The effects of operating parameters on the process performance were then examined by response surface methodology (RSM) models. The results showed that initial TOC concentration was the most important parameter influencing negatively the percentage of NP degradation. Afterward, optimization of the process revealed that the energy consumption could be minimized at 31.2 mA/cm2, 0.025 mol/L [Na2SO4], and 52 min treatment time for 52.2 mg/L initial TOC. Finally, analysis of treated LWW showed no toxicity on Daphnia magna. This study showed that the electro-peroxidation process can completely degrade NPs in LWW without any remaining toxic compounds.

The mixed-order chlorine decay model with an analytical solution and corresponding trihalomethane generation model in drinking water

Ensuring effective drinking water disinfection, remaining a certain amount of residual chlorine, and controlling disinfection by-product formation were very important for guarantying water quality safety and protecting public health; thus, the chlorine decay model and corresponding disinfection by-product formation model were necessary. This paper proposed a mixed-order chlorine bulk decay model (two parameters) based on Taylor's formula and derived its analytical solution. The accuracy of the mixed-order model was evaluated by comparing it with the nth-order model. To optimize the model and reduce the number of parameters required to be calibrated, the relationship of parameters with temperature, initial chlorine concentration, TOC and inorganic substance (ammonia nitrogen and iodide ion) was explored. The result proved that one of the parameters could be regarded as temperature dependent only. Meanwhile, the temperature equation of the model parameters was established by the Arrhenius formula. Subsequently, this paper selected trihalomethane as the target and study the linear relationship between chlorine consumption and trihalomethane formation. The results indicated that the liner slope had little correlation with initial chlorine concentration and temperature. On this basis, the corresponding trihalomethane model was built and its performance was proven to be good. The modeling developed in this work could be applied to drinking water distribution systems for residual chlorine and trihalomethane prediction, and provided a reference for the decision involving water quality.

Developing Pt-M/C catalyst (M=Pb, Cu) for efficient catalytic wet air oxidation of phenol wastewater under mild conditions

Catalytic wet air oxidation (CWAO) is a promising process for degrading phenol in wastewater to CO2 and H2O. To achieve an active and stable Pt catalyst working at lower temperature, efficient catalysts are here developed by building a Pt-M (M=Pb, Cu) alloy structure where Pt is mainly in the form of Pt0 while M is mainly in the form of M2+. Firstly, carbon supported Pt-Pb/XC-72R and Pt-Pb/EC-300 catalysts are prepared for CWAO of phenol wastewater. It is found that Pt-Pb/XC-72R is highly active and stable for CWAO of phenol even at 100 °C. The initial TOC conversion is 91.1% and can be maintained higher than 75% in five consecutive cycles. Contrarily, Pt-Pb/EC-300 rapidly deactivates and TOC conversion decreased from 91.2% to 47.1% after five cycles. The characterization results indicate that two Pt-Pb alloy catalysts contained comparably high Pt0 concentration, which is responsible for the high activity. However, the Pb2+ concentration of Pt-Pb/XC-72R is much higher than that of Pt-Pb/EC-300, and higher Pb2+ concentration favors surface oxidation and keeps Pt0 from being oxidized during CWAO process, thus enhancing stability. For Pt-Pb/EC-300, both Pt0 and Pb0 are oxidized during the reaction, resulting in deactivation. To avoid using Pb in environmental considerations, the Pt-Pb is then replaced by Pt-Cu nanoparticles, where high catalytic activity and stability are maintained. More importantly, increasing Cu2+ can further enhance the catalytic performance. Tuning the second metal chemical state of Pt-based bimetallic alloy can be an effective approach to develop new catalysts for CWAO technology.

A bionic solar-driven interfacial evaporation system with a photothermal-photocatalytic hydrogel for VOC removal during solar distillation

Solar-driven interfacial evaporation is a breakthrough water treatment method because it harvests solar energy for producing clean water. However, evaporated volatile organic compounds (VOCs) in distilled water are the greatest barrier to this technology. Herein, a bionic solar-driven interfacial evaporation system integrating photothermal and photocatalysis technology was developed based on a new combined material TiO2/Ti3C2/C3N4/PVA (TTCP) hydrogel as an evaporator. Phenol-contaminated water, especially actual water (seawater, lake water and reclaimed water), is used to evaluate the water evaporation and VOC photocatalytic degradation performance. The results show that the evaporation rate of TTCP hydrogel was 1.54 kg m − 2h − 1 under 1 kW m − 2, and the removal efficiency of phenol ranged from 69.4% to 100% at different concentrations (1–50 mg/L) in source water. Particularly, the capacity of the bionic evaporator was first evaluated for different types of actual water. Despite the initial TOC (38.12–57.93 mg/L) and total dissolved solids (TDS, 1.35×103–8.78×104 mg/L) for seawater, lake water and reclaimed water being very different, the TDS was decreased by more than two orders of magnitude, below the US EPA drinking water standard (500 mg/L). The maximum TOC removal efficiency reached 80% under simulated sunlight (1 kW m − 2), which is comparable to the efficiency of the ultrafiltration technique previously reported except for seawater. Furthermore, real sunlight (average solar irradiation ∼0.82 kW m- 2) was used to assess the practicability. The bionic evaporator can produce 0.72 kg m − 2h − 1 of vapor from reclaimed water and run with steadily efficient TDS and TOC removals, reaching 99% and 74%, respectively. This technology, as a small, decentralized water treatment method, is a good choice for remote and off-grid areas.

Activation of periodate using ultrasonic waves and UV radiation for landfill leachate treatment.

In the present work, saline leachate of the Bushehr coastal city (Iran) was purified using the ultraviolet/ultrasonication wave/periodate process. The initial TDS and TOC values of the leachate studied were 7390mg/L and 975mg/L, respectively. During the effect of various parameters on leachate purification, the experiments were optimized at pH 3, oxidizer concentration of 4mM, and treatment time of 120min. The initial BOD5/COD ratio of 0.66 was reduced to 0.42 at the end of the purification time (120min). After leachate treatment under optimal conditions, the amount of BOD5, COD, and UV254 were 451.5mg/L, 1072mg/L, and 12.69cm-1, respectively. Concentrations of heavy metals in crude leachate by ICP-OES were checked. Also, the concentration of organic compounds before and after purification was determined using GC-Mass. The leachate purification kinetics followed the first-order model using the designed method. Based on the COD factor, the system energy consumption for leachate treatment was calculated to be 11.4 kWh/m3. The results showed that the system explored (UV/US/IO4-) can effectively purify high salinity waste leachate.

Degradation of phthalic acid by anodic oxidation in acidic aqueous solutions with high chromium content using boron-doped diamond anode

Mineralization of phthalic acid, a highly refractory organic pollutant was studied by an anodic oxidation process with boron-doped diamond (BDD) anode in a highly acidic chromium medium. Synthetic solutions were composed of Cr(III)/Cr(VI), sulfate, sulfuric acid, and phthalic acid (initial form potassium hydrogen phthalate, KHP). Degradation/mineralization of KHP was carried out by hydroxyl radicals produced on the anode and sulfate radicals generated from the sulfate ions present in the medium. To find appropriate operating conditions, the effects of cathode type, current density, electrolysis time, and presence of Cr(VI)-Cr(III) were investigated. Thereafter, the effect of current density, amount of Cr(VI)-Cr(III) in solution, and electrolysis time on KHP mineralization was realized by using response surface methodology and central composite design. The most effective TOC removal rate was found as 94.8% in the case of 0.675% Cr(VI) and 3.825% Cr(III) content by mass at 80 mA cm−2 of current density and 360 min of electrolysis time, despite a high initial TOC content of 9400 mg L−1. As a result, the organic content of the wastewater was removed by electro-persulfate process via the catalytic effect of Cr species. Additionally, the use of BDD anode avoided metal ion pollution that could dissolve from different anode materials like PbO2 and affect the chromium recovery efficiency.

Construction of Novel Electro-Fenton Systems by Magnetically Decorating Zero-Valent Iron onto RuO2-IrO2/Ti Electrode for Highly Efficient Pharmaceutical Wastewater Treatment

The Electro-Fenton (E-Fenton) technique has shown great potential in wastewater treatment, while the sustainable and continuing supply of Fe2+ remains challenging. Herein, we demonstrate the construction of a novel E-Fenton system by magnetically decorating zero-valent iron (ZVI) onto a RuO2-IrO2/Ti (ZVI-RuO2-IrO2/Ti) electrode for high-efficient treatment of pharmaceutical wastewater, which is considerably refractory and harmful to conventional biological processes. By using ZVI as a durable source of Fe(II) irons, 78.69% of COD and 76.40% of TOC may be rapidly removed by the developed ZVI-RuO2-IrO2/Ti electrode, while the ZVI-RuO2-IrO2/Ti electrode using ZVI only reduces 35.64% of COD under optimized conditions at initial COD and TOC values of 5500 mg/L and 4300 mg/L, respectively. Moreover, the increase in BOD5/COD from 0.21 to 0.52 highlights the enhanced biodegradability of the treated effluent. The analysis of a simultaneously formed precipitation on electrodes suggests that the coagulation process dominated by Fe3+/Fe2+ also plays a non-negligible role in pharmaceutical wastewater treatment. In addition, the monitoring of the evolution of nitrogen elements and the formation of by-products in the E-Fenton process verifies its great capacity toward those organic pollutants found in pharmaceutical wastewater. Our study offers a practical solution for enhancing the performance of E-Fenton systems, and effectively treating refractory pharmaceutical wastewater.

Soil Carbon Dynamics, Sequestration and Productivity of Predominant Cropping Systems under Long Term (9 years) Inorganic and Organic Fertilization in Semi-Arid Deccan Plateau, India

Soil organic carbon (SOC) sequestration in agricultural soils is one of major agricultural strategies to mitigate the greenhouse gas (GHG) emissions as it is a potential sink for atmosphere carbon. Cropping systems and management practices adopted will affect the SOC sequestration. Dynamics of SOC is very important for understanding the pathways of C stabilization into different SOC pools. An attempt was made to assess the importance of different cropping systems on C sequestration and its stabilization in a 9 year old experiment at PJTSAU, Hyderabad, India. In comparison to initial TOC, cropping system perennial super napier fodder showed greater C build up (46.5%) followed by maize intercropped with pigeonpea followed by sunhemp (23.1%). In fact, all the cropping systems there were net increases in TOC. There was only 6.86% of C applied through various sources was stabilized as SOC. A minimal input of 1.24 Mg C ha-1 yr-1 is needed to maintain SOC level. Cropping system perennial super napier fodder showed a higher carbon management index (145.9), sustainable yield index (64.1), BC ratio (16.99) and least amount is required to sequester the kg of carbon to soil (Rs. 59).

UVA LEDs and solar light photocatalytic oxidation/ozonation as a tertiary treatment using supported TiO2: With an eye on the photochemical properties of the secondary effluent

Photocatalytic oxidation/ozonation of a mixture of eight pharmaceuticals added to a secondary effluent, SE, of an urban wastewater treatment plant has been studied using TiO2 supported on commercial Al2O3/SiO2 ceramic foams. As radiation source UVA LEDs (365 nm) or solar radiation was used. Pharmaceuticals were added at high (1 mg L−1 each) or relatively low (50 μg L−1 each) concentration, contributing 25% and 1.5% to the initial TOC, respectively. Under both types of radiation, the photolysis of SE generated reactive species capable of degrading the contaminants (indirect photolysis), this effect being greater at lower initial concentration of pollutants. Lower concentration of contaminants also favoured their degradation and the SE mineralization by photocatalytic oxidation, whereas its effect on ozonation was low. The best results were obtained by photocatalytic ozonation, especially in terms of COD removal, without observing any synergism or antagonism between O3/Radiation and TiO2/Radiation systems. In SE, the performance of the supported catalyst resulted much better than that of suspended TiO2 P25, which showed almost no activity in this matrix. Through different cycles of reuse, the stability of the supported catalyst was confirmed.

Development of a Continuous Photo-catalytic/Ozonation System: Application on Amido Black Removal from Water

ABSTRACT A continuous system for photo-catalytic/ozonation was designed at laboratory scale and evaluated for water treatment using Amido Black 10B dye (AB) as a pollutant model. The effect of single ozonation (O3), photolytic ozonation (UV/O3) and combined photocatalytic/ozonation treatment (UV/O3/TiO2) were investigated. TiO2 nanocatalysts films were coated on stainless steel grids (AISI 304) by Atomic Layer Deposition technique (ALD) at 350 °C. An experimental hydrodynamic study of the designed reactor was conducted based on dry and total pressure drop. Three flow regimes were observed by increasing the total pressure drop against gas load factor (Fs). Depollution experiments conducted on the developed reactor showed that reaction rates and efficiency of studied processes were dependent on the studied operational parameters (initial dye concentration, ozone dose, pH). The maximum AB dye ([AB]0 = 100 mg. L−1) conversion efficiency, using the designed (UV/O3/TiO2) system, was about 40.3% of initial TOC and 100% AB color removal was achieved within 10 min at an optimal ozone dose of 132 mg. L−1. A significant improvement in AB removal using UV/TiO2/O3 process (koverall = 0.056 min−1, 40.3%) compared to O3 alone (koverall = 0.032 min−1, 26.87). Results shows also that the addition of tert-butanol (TB), as radical scavenger ([TB] = 0.2 M and 0.4 M), greatly affects the reaction mechanisms of a photocatalytic ozonation process within 5 min of reaction, by decreasing the Amido Black conversion from 99.67% ([TB] = 0 M) to 74.63% and 31.35%, respectively, in presence of 0.2 M and 0.4 M of tert-butanol. The remarkable decrease in AB removal rate observed in the presence of a radical scavenger expresses that there was an obvious enhancement of hydroxyl radical OH• generation due to the synergetic effect between ozone and photocatalytic processes.

Au@CoS-BiVO4 {010} Constructed for Visible-Light-Assisted Peroxymonosulfate Activation

A visible-light-Fenton-like reaction system was constructed for the selective conversion of peroxymonosulfate to sulfate radical. Au@CoS, when doped on monoclinic BiVO4 {010} facets, promoted spatial charge separation due to the different energy band between the m-BiVO4 {010} and {110} facets. The visible-light response of m-BiVO4 was enhanced, which was attributed to the SPR effect of Au. And the photogenerated electrons were transferred from the m-BiVO4 {010} facet to Au via a Schottky junction. Owing to higher work function, CoS was able to capture these photoelectrons with acceleration of the Co(Ⅱ)/Co(Ⅲ) redox, enhancing peroxymonosulfate conversion to sulfate radical (Co2+ + HSO5−→ Co3+ + •SO4− + OH−). On the other hand, holes accumulated on m-BiVO4 {110} facets also contributed to organics oxidation. Thus, more than 95% of RhB was degraded within 40 min, and, even after five cycles, over 80% of RhB could be removed. The radical trapping experiments and EPR confirmed that both the sulfate radical and photogenerated hole were the main species for organics degradation. UV-vis DRS, photoluminescence (PL) and photoelectrochemical analyses also confirmed the enhancement of the visible-light response and charge separation. In a pilot scale experiment (PMS = 3 mM, initial TOC = 151 mg/L, reaction time = 4 h), CoS-Au-BiVO4 loaded on glass fiber showed a high mineralization rate (>60%) of practical wastewater.

Enduring reduction of carbon and nitrogen emissions from landfills due to aeration?

The objective of the present work is to investigate to what extent emission reductions observed during landfill aeration are permanent. To do so, lab-scale degradation experiments using waste from an old landfill have been conducted under different conditions (anaerobic, (partly) aerobic returning to anaerobic, aerobic) and balances for carbon and nitrogen have been established. For the latter, all emissions of C and N (except N2) and their pools at the start and end of the experiment have been determined. In addition, the chloroform fumigation-extraction method (biocidal treatment) has been applied to determine microbially bound carbon and to estimate nitrogen in microbial biomass accordingly. The results reveal that 18g TOC·kg DM-1 of the waste material were mineralized during aerobic treatment for 699days, which is equivalent to about 14% of the initial TOC content. For the anaerobic treatment, only 10g TOC·kg DM-1 were released. For the aerobic-anaerobic reactors, a slight increase in methane emissions approximately 10months after termination of aeration was observed. With respect to leachate emissions, the results indicate significantly lower emission levels (factor 1.5 for TOC and factor 4 for TN) for the reactors, which were aerated at least sometimes. The biocidal treatment highlights that this emission reduction is rather based on an increased sorption capacity of aerated waste (higher ion exchange capacity) than a lower overall pollutant potential. It is shown that regardless of the operation mode, most nitrogen remained in solids (83.1-92.6%) and is subject to internal recycling during waste degradation.

Insights of emerging contaminants removal in real water matrices by CWPO using a magnetic catalyst

The study was focused on the application of catalytic wet peroxide oxidation (CWPO) with a synthesized magnetic catalyst (Fe3O4/MWCNTs) for the treatment of real water matrices spiked with pharmaceutical compounds. CWPO was carried out by modifying the initial pH of surface water (SW), wastewater treatment plant (WWTP) effluent, brewery wastewater (BW) and hospital wastewater (HW), and the effect of the addition of the emerging pollutants naproxen (NAP) and diclofenac (DCF). From the experimental results, pH and concentration of NAP and DCF in CWPO were crucial factors in the successful pollutants removal from water matrices. The lab-prepared catalyst showed high removal rates of NAP and DCF from different water matrices spiked with the NAP-DCF mixture at pH 5.0. The highest average removal rate of TOC (75%), NAP (66%), DCF (76%), TN (39%) and aromaticity (68.39%) was obtained for SW matrix using 1.0 g L−1 of catalyst, pH ≈ 5.0, 5 mM of H2O2 and 60 °C. The mineralization decreased with the increase of the initial TOC concentration of the tested matrix. By CWPO tests of the real water matrices it was demonstrated that DCF removal was higher than NAP. From the recyclability tests, the catalyst demonstrated high activity and stability along three consecutive CWPO cycles of 8 h each one. The pseudo-second order model well-described the degradation of NAP and DCF. Finally, aromaticity and toxicity of the effluents were greatly reduced after CWPO treatment. This work demonstrated that CWPO with the magnetic catalyst is an efficient method to remove DCF-NAP mixtures from real aqueous matrices.

Optimization of photo-electro/Persulfate/nZVI process on 2-4 Dichlorophenoxyacetic acid degradation via central composite design: a novel combination of advanced oxidation process.

2-4 Dichlorophenoxy acetic acid is most publicly applied from chlorinated phenoxy acids herbicides. In this research, central composite design for optimization of photo-Elecro/persulfate/nZVI process to degradation and mineralization of this herbicide in aqueous solution to environment protection was applied. The initial pH (2-4), persulfate anion concentration (0.25-0.5mg/L), direct electrical (0.5-1 A), herbicide concentration (50-100mg/l), nZVI dose (0.05-1mg/L), and reaction time (50-100mg/l) are independent variables optimized. Also, the synergist effect, COD and TOC removal, the effect of radical scavengers, and by-products were investigated. The fitting of the model, suggested a quadratic model (R2 = 0.9926). F-value and P value of ANOVA were 719.81 and 0.0001 respectivelty. After optimizing the PEP/nZVI process, the proposed optimal conditions was pH = 3.4, persulfate concentration equal to 0.49mg/l, in 1 A direct current, nZVI dose equal to 0.1mg/l, in 50.05mg/l herbicide concentration as an initial concentration, in 80min reaction time. The theoretical and actual removal was evaluated 91.99% and 92%, respectively. In the optimum condition, 45.4% synergist effect indicated. 78.3% and 66.5% of initial COD and TOC were decreased. 39.02% of Cl ion was released form 2,4-D structure. The presence of radical scavengers have an adverse impact on the performance of process. The highest amount of radical scavenging was in methanol, tert-butyl alcohol and bicarbonate ions at concentrations at 50mM/l. The kinetic data was fitted via pseudo-first-order reaction (R2 = 0.99).The direct and indirect oxidation process lead to formation of several organic by-products which were confirmed by GC-MS analysis.

Effective treatment of high-salinity landfill leachate using ultraviolet/ultrasonication/ peroxymonosulfate system

Landfill leachate, as a complex medium with a high concentration of organic and mineral materials, is a serious problem for the environment. In the current study, the saline landfill leachate of Bushehr coastal city (Iran) was treated using ultraviolet/ultrasonic waves/peroxymonosulfate system. The initial TOC and TDS of the studied leachate was 915 mg/L and 7390 mg/L, respectively. The system had the maximum efficiency at conditions of pH 3, peroxymonosulfate (PMS) of 4 mM, and reaction time of 150 min. Based on the findings, the initial ratio of BOD5/COD (0.66) was reduced to 0.38 using the developed system. After treatment of the landfill leachate at the optimal condition, the values of COD, BOD5, and UV254 were reached to 983 mg/L, 348 mg/L, and 10.16 cm−1, respectively. The concentration of all studied elements (except Pb, As, and Ca) increased after purification. According to the GC-mass spectrometry, the molecular weight and concentration of organic matter in raw leachate were higher than that of the treated one. The studied system had an energy consumption value of 86 kW·h/m3 for the treatment of landfill leachate. The results confirm the effectiveness of the ultraviolet/ultrasonic waves/PMS system for the treatment of high saline landfill leachate.

Integration of sub-stoichiometric titanium oxide reactive electrochemical membrane as anode in the electro-Fenton process

Sub-stoichiometric titanium oxide (TiOx) reactive electrochemical membrane (REM) were integrated for the first time as anode in the electro-Fenton (EF) process. Hydroxyl radicals (OH) were produced both in the retentate from Fenton’s reaction and at the REM from anodic oxidation (AO). Optimal mass transport conditions were implemented because of convection-enhanced mass transport of (i) organic pollutants towards the REM surface during filtration and (ii) dissolved O2 towards cathode active sites owing to the use of a 3D carbon felt cathode in flow-through configuration for H2O2 generation. The efficiency of the REM/EF process was much higher than EF or REM used as standalone processes. For instance, taking paracetamol as target pollutant, (67 ± 2)% removal of 55 mg L−1 of initial TOC was achieved with a high mineralization current efficiency (MCE) of (43 ± 1)%. By comparison, standalone REM and EF processes achieved only 47% (MCE = 30%) and 31% (MCE = 20%) of TOC removal, respectively. By monitoring TOC removal both in retentate and permeate, the effect of homogeneous oxidation in the bulk retentate and heterogeneous oxidation at the REM could be observed separately. It was thus highlighted that the efficiency of AO might be affected by the presence of OH and Fe2+ in the bulk. It was also emphasized a synergistic effect related to the formation of carboxylic acids in the bulk retentate that are more easily mineralized at the REM where both OH-mediated oxidation and direct electron transfer occur.