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The high internal resistance (Rint) that develops across the sediment microbial fuel cells (SMFC) limits their power production (~4/10 mW m−2) that can be recovered from an initial oil-contaminated sediment (OCS). In the anolyte, Rint is related to poor biodegradation activity, quality and quantity of contaminant content in the sediment and anode material. While on the catholyte, Rint depends on the properties of the catholyte, the oxygen reduction reaction (ORR), and the cathode material. In this work, the main factors limiting the power output of the SMFC have been minimized. The power output of the SMFC was increased (47 times from its initial value, ~4 mW m−2) minimizing the SMFC Rint (28 times from its initial value, 5000 ohms), following the main modifications. Anolyte: the initial OCS was amended with several amounts of gasoline and kerosene. The best anaerobic microbial activity of indigenous populations was better adapted (without more culture media) to 3 g of kerosene. Catholyte: ORR was catalyzed in birnessite/carbon fabric (CF)-cathode at pH 2, 0.8M Na2SO4. At the class level, the main microbial groups (Gammaproteobacteria, Coriobacteriia, Actinobacteria, Alphaproteobacteria) with electroactive members were found at C-anode and were associated with the high-power densities obtained. Gasoline is more difficult to biodegrade than kerosene. However, in both cases, SMFC biodegradation activity and power output are increased when ORR is performed on birnessite/CF in 0.8 M Na2SO4 at pH 2. The work discussed here can focus on bioremediation (in heavy OCS) or energy production in future work.

This study represents the first application of Fe–citrate-based photo-Fenton chemistry for the degradation of chlorpyrifos (CPF) spiked into agricultural runoff, and its phytotoxicity assessment. The effects of the initial CPF concentration, time and ratio of Fe–citrate/H2O2 on CPF removal during the photo-Fenton reaction were investigated and modeled with analysis of variance using R software by the response-surface methodology package. According to the stationary point in original units, the optimal condition for 70.00% CPF removal was as follows: CPF = 2.5 mg L−1 (0.0), time = 48.0 min (0.585) and Fe–citrate/H2O2 = 0.075 (0.539). Beside running the system at near-neutral pH, another strength of this study is related to the treatment of agricultural runoff contaminated with CPF with a raceway pond reactor, which has the advantages of simplicity of the facilities and procedures, as well as the possibility of using sunlight more efficiently in the field of applications. Finally, untreated and treated agriculture runoffs were used as irrigation to determine their phytotoxic effects on seed germination of cress (Lepidium sativum). Solar photo-Fenton treatment greatly reduced phytotoxicity of agriculture runoff and showed the highest germination percentage (70%) compared to both raw agricultural runoff (60%) and untreated CPF-spiked runoff (35%).

Anaerobic biodegradation of petroleum-contaminated sediments can be accomplished by a sediment microbial fuel cell (SMFC), but the recovered energy is very low (~4 mW m−2). This is due to a high internal resistance (Ri) that develops in the SMFC. The evaluation of the main experimental parameters that contribute to Ri is essential for developing a feasible SMFC design and this task is normally performed by electrochemical impedance spectroscopy (EIS). A faster and easier alternative procedure to EIS is to fit the SMFC polarization curve to an electrochemical model. From there, the main resistance contributions to Ri are partitioned. This enables the development of a useful procedure for attaining a low SMFC Ri while improving its power output. In this study, the carbon-anode surface was increased, the biodegradation activity of the indigenous populations was improved (by the biostimulation method, i.e., the addition of kerosene), the oxygen reduction reaction was catalyzed, and a 0.8 M Na2SO4 solution was used as a catholyte at pH 2. As a result, the initial SMFC Ri was minimized 20 times, and its power output was boosted 47 times. For a given microbial fuel cell (MFC), the main resistance contributions to Ri, evaluated by the electrochemical model, were compared with their corresponding experimental results obtained by the EIS technique. Such a validation is also discussed herein.

The photocatalytic activity of TiO

This paper deals with the use of a raceway pond reactor (RPR) as an alternative photoreactor for solar photocatalytic applications. Raceway pond reactors are common low-cost reactors which can treat large volumes of water. The experiments were carried out with TiO2 in the agriculture effluent spiked with Chlorpyrifos (CPF) at circumneutral pH. The Response Surface Methodology (RSM) was used to find the optimum process parameters to maximize CPF oxidation from the mathematical model equations developed in this study using R software. By ANOVA, p-value of lack of fit > 0.05 indicated that, the equation was well-fitted. The theoretical efficiency of CPF removal, under the optimum oxidation conditions with UV solar energy of around 697 ± 5.33 lux, was 84.01%, which is in close agreement with the mean experimental value (80 ± 1.42%) confirming that the response model was suitable for the optimization. As far as the authors know, this is the first study of CPF removal using RPR in agriculture runoff at circumneutral pH.

Central composite design with response surface methodology was applied to optimize the main experimental parameters such as current, time, As(III) concentration, and hardness for arsenic (III) removal in hard water by the electrocoagulation process. The main aim was to find the optimum process parameters to maximize arsenic removal from the mathematical model equations developed in this study using R software. By variance and regression analysis, the linear regression equation was established as a predicted model. The R2 of 0.93 indicated that the equation was well fitted. The optimum condition of 99% of As(III) removal for current (A), time (min), As(III) concentration (ppb), and hardness (mg/L as CaCO3) is 0.07, 37, 274, and 324, respectively. ANOVA analysis shows no significant difference between the observed and predicted values (p-value > 0.05) which shows good fit to the model.

At the end of December 2019, the rapid spread of the COVID-19 (SARS-CoV-2) disease and, subsequently, deaths around the world, lead to the declaration of the pandemic situation in the world. At the beginning of the epidemic, much attention is paid to person-to-person transmission, disinfection of virus-contaminated surfaces, and social distancing. However, there is much debate about the routes of disease transmission, including airborne transmission, so it is important to elucidate the exact route of transmission of the COVID-19 disease. To this end, the first systematic review study was conducted to comprehensively search all databases to collect studies on airborne transmission of SARS-CoV-2 in indoor air environments. In total, 14 relevant and eligible studies were included. Based on the findings, there is a great possibility of airborne transmission of SARS-CoV-2 in indoor air environments. Therefore, some procedures are presented such as improving ventilation, especially in hospitals and crowded places, and observing the interpersonal distance of more than 2 m so that experts in indoor air quality consider them to improve the indoor air environments. Finally, in addition to the recommendations of the centers and official authorities such as hand washing and observing social distancing, the route of air transmission should also be considered to further protect health personnel, patients in hospitals, and the public in other Public Buildings., Graphical abstract Image 1, Highlights • The SR was conducted to compile studies on airborne transmission of virus in indoor air. • In total, 14 relevant and eligible studies were included. • There is a great possibility of airborne transmission of SARS-CoV-2 in indoor air. • Improving ventilation is essential, especially in hospitals and crowded places.

Environmental exposure to nonylphenol (NP) can adversely affect human and wildlife health. A systematic review was conducted to evaluate the relationship between environmental NP exposure and cancer progression risk. Literature surveys were conducted within several international databases using appropriate keywords. A comprehensive search yielded 58 eligible studies involving a wide range of adverse effects, exposure assessment methods, study designs, and experimental models. Most studies reported that NP strongly induced breast cancer progression in intended experiments. Positive associations between NP exposure and ovarian, uterine, pituitary, and testicular cancers were also reported. Although some studies reported no relation between environmental NP exposure and tumour and/or cancer progression, NP (a known endocrine disrupting chemical) induced action mechanisms in multiple experimental models and may interfere with/hyper-activate oestrogen signalling. Secretion of oestrogen and development of reproductive tissues like breasts, uteruses, and ovaries showed strong associations with possible neoplasia (i.e., uncontrolled development of tumours and/or malignant cancers). Findings of this study are important for informing policymakers to pass legislation limiting the use of environmental contaminants such as NP before all adverse effects of exposure have been determined.

TiO 2 electrode was used as photo-driven anode for oxygen reduction at carbon-felt cathode to produce H 2 O 2 used in the Fenton reaction to decompose an acid green 50 textile dye (AG50). The H 2 O 2 generated was catalyzed with ferrous ions in the photoelectroFenton process to decompose AG50 in cathode compartment. TiO 2 nanocomposite electrode was prepared by electrochemical anodization of pure Ti substrates. The results showed that TiO 2 anode exhibited a porous surface and organized nanotubes annealed at 450 °C and 600 °C with anatase phase, while a surface with less porous density with compact bars was obtained at 700 °C with anatase/rutile phase. The influence of applied bias potential, concentration of methanol in the anolyte, annealing temperature of TiO 2 nanocomposite and pH of the anolyte were studied on the photoelectrocatalytic degradation of methanol, whereas the catholyte composition remained unchanged for H 2 O 2 electrogeneration. Higher mineralization of both organic compounds was obtained by increasing the annealing temperature under acidic conditions using a bias potential of 1.02 V.

−Shewanella putrefaciens Bioelectrochemical systems Metal-deposition a b s t r a c t The microbiological influence of gram negative dissimilative bacteria on the electrodeposition of gold [AuCl4] − ion is analysed. Previous investigations have shown positive shifts in revisable potentials of gold in the presence of initially live gram negative bacterial cells, Shewanella putrefaciens in the electrolyte bath. This manuscript gives further analysis of the experimental data, with hypothetical influences of bacterial cells on gold nucleation and electrodeposition reaction mechanisms, kinetics and mass transfer as a basis for further investigation and strategies for the engineering of robust bioelectrochemical systems (BES), for novel metal ions recovery from aqueous process streams.

Atrazine is a highly persistent and carcinogenic compound used as herbicide around the world. This compound has been banned in USA and some European countries but in Mexico it is still widely used in the agriculture. In order to achieve a high mineralization of atrazine, present as active compound in the Gesaprim commercial herbicide, detoxification studies in two-compound parabolic solar reactors by means of photo-Fenton process followed by TiO 2 photocatalysis was carried out. The atrazine contents in the Gesaprim solutions tested were 35 mg L −1 (19.0 mg L −1 of TOC) and 20 mg L −1 (9.5 mg L −1 of TOC). [H 2 O 2 ] 0 /COD 0 ratios of 1, 3 and 5 (1.5 × 10 −3 , 4.5 × 10 −3 and 7.5 × 10 −3 mol L −1 H 2 O 2 , respectively) were evaluated in combination with 5 mg L −1 and 10 mg L −1 Fe 2+ at pH 2.8 in the photo-Fenton oxidation; whereas, in the photocatalytic process, the influence of the pH (4.8, 7.0 and 11.0) and type of TiO 2 (Degussa P25 and HB) were studied with TiO 2 content of 200 mg L −1 . The study showed that photo-Fenton process followed by TiO 2 photocatalysis produce a 72% of mineralization (for an initial TOC of 19 mg L −1 ) and decrease above 90% of toxicity in compliance with NMX-AA-110-1995-SCFI1 Mexican Norm. In order to established a minimum amount of chemical reagents these photodegradation processes were carried out with special emphasis on the optimization of experimental parameters such as concentrations of photocatalyst and oxidant. Atrazine mineralization was influenced by the pH of the solution, the initial concentration of hydrogen peroxide and iron ions.

The oxidation of Acid Green 50 (AG50) textile dye using Fe2O3–Al2O3, prepared from the calcination of FeIII–Al(OH)4-gel, as a highly active catalyst in the heterogeneous Fenton oxidation process was studied. It was found that the ferric ions loaded on the surface of neutral Al(OH)4− gel and then calcined at different temperatures is an efficient catalyst in the heterogeneous Fenton reaction for the mineralization of aqueous AG50. According to the X-ray analysis, the iron catalyst is a mix of Fe2O3 and Al2O3. The thermal treatment gives long-term stability to the catalyst because it minimizes iron leaching from the catalyst. The catalyst was used in four successive recycling heterogeneous Fenton oxidations generating a colorless solution with the removal of over 95% of total organic carbon (TOC) in 90 min. This shows that the Fe2O3–Al2O3 catalyst is highly efficient for the degradation of AG50 after being used in several cycles during the dye treatment. It was also found that the degradation of AG5...

TiO 2 and silver doped TiO 2 films (photoanodes) were prepared by the sol–gel method using silver contents of 1%, 3% and 5% (w/w). Photoelectrocatalytic activity of these photoanodes was evaluated by monitoring the photocatalytic decomposition of methanol and basic orange II (BOII) in aqueous solution under visible light illumination at pH 3 adjusted with HClO 4 by the application of potential bias. Enhanced photoelectrocatalytic activity was found by the application of 0.4 V ( vs . SCE) bias potential under visible light illumination. A detrimental effect was observed on the photoelectrocatalytic activity of the TiO 2 photoanodes in the presence of BOII, and is evident from the low photocurrents; however, the presence of silver in the TiO 2 films increased the photoelectrocatalytic activity. Also the photoelectrolysis of methanol removed over 80% of total organic carbon in 5 h of reaction under visible light and 0.4 V ( vs . SCE) bias potential. Nevertheless, negligible TOC removal was observed for the BOII photoelectrolysis with or without bias potential and under visible light illumination or in dark. Less than 9% of discoloration was achieved at the 3% Ag–TiO 2 photoanode under visible light illumination and bias potential.

We report influences of the gamma proteobacteria Shewanella putrefaciens CN32 on electronation and electrodeposition phenomena of gold, cobalt and iron ionic species dissolved in aqueous effluents of low pH as novel strategies for the recovery and remediation of these metals. Linear sweep and cyclic voltammetry was used and analysed for the evaluation of changes of respective electron transfer reactions occurring at the electrified interface of graphite electrode for electrolytes of pH 2 and low metal ion concentrations of 200 ppm. This study focuses on changes in electronation thermodynamics, preliminary results show shifts in the reverse potentials of gold electrodeposition and ferric iron electronation with implications for energy savings.

The removal of total organic carbon (TOC) from wastewater generated from phenolformaldehyde resin manufacturing industry using the electrocoagulation process was studied in this paper. Experiments were carried out at current densities of 5.0, 7.5 and 10.0 mA/cm2 using iron electrodes connected in parallel arrangement in an undivided electrochemical reactor. TOC content was determined during the different stages of electrolysis in order to know the feasibility of the electrocoagulation treatment for highly concentrated bio-refractory organic pollutants present in the industrial wastewater. Different operational conditions such as pH, time, and electrical conductivity were studied for TOC removal. Experimental values indicated that the electrocoagulation process showed high TOC removal efficiencies, 78.7% within 60 min of electrolysis, with an initial concentration of 23.8 × 103 mg/l TOC. Thus, these results showed that the electrocoagulation process is effective for the removal of initially high T...

Fe-doped TiO2 was prepared by the sol gel method and characterized by X-ray diffraction. All the Fe-doped TiO2 were composed of an anatase crystal form. The activity of the Fe-doped TiO2 for the degradation of the gesaprim commercial herbicide (which contains atrazine as active compound and formulating agents) was studied by varying the iron content during UV (15 W), visible light and solar irradiations. The visible light came from commercial saving energy lamps (13, 15 and 20 Watts). The gesaprim degradation rate depended on the iron content in the photo catalyst. The Fe-doped TiO2 (0.5% by weight of TiO2) showed higher TOC removal under visible light and was more active than the undoped TiO2 photo catalyst under the light irradiation sources tested. Over 90% of chemical oxygen demand abatement was achieved with both UV and visible light but less time was required to decrease the chemical oxygen demand content by using the catalyst doped with iron at 0.5% under visible light. It was observed that the degradation of gesaprim increased by increasing the iron content in the catalyst under visible light.

The Ca₃Zr₂S₇ films were deposited by electrodeposition by means of linear voltammetry with a potential applied in the range of -0.1 to -3.0 V vs. SCE. The precursors used for Ca, Zr and S were calcium acetate, zirconium acetate and sodium sulfite, respectively. The films were characterized optically, morphologically and structurally. The presence of Ca, Zr and S elements was verified by energy dispersion spectroscopy analysis. The results of the X-ray diffraction showed the presence of peaks related to a structure belonging to the perovskite family, and the chemical bonds were confirmed by photoelectron spectroscopy emitted by X-rays. The electrical resistivity in the dark and light was also measured. The surface roughness of the Ca₃Zr₂S₇ film was estimated at 3.05 nm with a thickness of 600 nm. It was found that the material absorbs in the visible region of the electromagnetic spectrum with a wavelength of less than 500 nm. The Ca₃Zr₂S₇ film also exhibits ferroelectric properties at room temperature.

The sonophotocatalytic degradation of basic blue 9 industrial textile dye has been studied in the presence of ultrasound (20 kHz) over a TiO(2) slurry employing an UV lamp (15 W, 352 nm). It was observed that the color removal efficiency was influenced by the pH of the solution, initial dye concentration and TiO(2) amount. It was found that the dye degradation followed apparent first order kinetics. The rate constant increased by decreasing dye concentration and was affected by the pH of the solution with the highest degradation obtained at pH 7. The first order rate constants obtained with sonophotocatalysis were twofold and tenfold than those obtained under photocatalysis and sonolysis, respectively. The chemical oxygen demand was abated over 80%.

The degradation of water soluble corn oil wastes was carried out by Fenton reaction and also under mildly basic media in the presence of oxidants, such as hydrogen peroxide and persulfate, assisted with solar light. The degradation efficiency was obtained by analysis of chemical oxygen demand, carbon dioxide and gas chromatography. Over 90% of both chemical oxygen demand abatement and carbon dioxide recovery was accomplished by Fenton reaction. The presence of oxidants during the photodegradation resulted in high chemical oxygen demand abatement of the oil waste with the disappearance of the majority of the initial fatty acids present in the oil waste before treatment.

The photocatalytic degradation of alazine and gesaprim commercial herbicides was carried out in aqueous TiO 2 suspensions under UV light (15 W, 352 nm). Degradation of these herbicides was also observed by the combined effects of photocatalysis with sonolysis (sonophotocatalysis) using an ultrasound source of 20 kHz. Degradation profiles were recorded by measuring the concentration of the active compounds present in the alazine (alachlor and atrazine) and gesaprim (atrazine) by HPLC as a function of irradiation time (sound and/or light). Over 90% of the active component in the gesaprim was abated and those in alazine were completely degraded. The content of total organic carbon and chemical oxygen demand was also monitored. Mineralization of the commercial herbicides was achieved. Over 80% of chemical oxygen demand abatement was attained for both herbicides with sonophotocatalysis at 150 min of irradiation time. The photocatalytic degradation of the herbicides followed a pseudo-first order kinetics and their rate constant was increased by the combined effects of sonolysis.

The degradation of azure B dye (C15H16ClN3S; AB) has been studied by Fenton, sonolysis and sono-electroFenton processes employing ultrasound at 23 kHz and the electrogeneration of H2O2 at the reticulated vitreous carbon electrode. It was found that the dye degradation followed apparent first-order kinetics in all the degradation processes tested. The rate constant was affected by both the pH of the solution and initial concentration of Fe2+, with the highest degradation obtained at pH between 2.6 and 3. The first-order rate constant decreased in the following order: sono-electroFenton > Fenton > sonolysis. The rate constant for AB degradation by sono-electroFenton is ∼10-fold that of sonolysis and ∼2-fold the one obtained by Fenton under silent conditions. The chemical oxygen demand was abated ∼68% and ∼85% by Fenton and sono-electroFenton respectively, achieving AB concentration removal over 90% with both processes.

Biodiesel produced from castor oil has attractive properties as this fuel can be produced from renewable energy sources without compromising food supply. A B20 castor biodiesel-diesel blend was used on a diesel engine without any other modification. A field study was conducted on a diesel school bus in the state of Morelos, Mexico, to evaluate fuel efficiency and fuel emissions from diesel and from the B20 castor biodiesel-diesel blend under bus driving conditions on the highway and in the urban area. Refined castor oil was used to produce biodiesel at pilot scale (300 liters) in compliance with the B100 ASTM D6751 standard. The results show the benefits of using castor biodiesel since, when com¬pared to diesel fuel, similar fuel efficiencies and reductions in exhaust emissions were accomplished with the B20 castor biodiesel-diesel blend. This blend represents an environmental-friendly alternative to reduce diesel consumption without threatening the food supply, because castor biodiesel is produced from wild plant oil.