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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%).

The advanced oxidation processes (AOPs), as an alternative technology to eliminate pesticides from aqueous environments, consist of several groups of technologies that have been used with high efficiency in the treatment of water and wastewater in recent decades. A systematic review of the scientific literature to evaluate the most common advanced oxidation processes (AOPs) for the removal of organophosphorus pesticides in aqueous matrices is addressed in this study. Meta-analysis is also performed to provide a precise and robust summary estimate after a systematic and rigorous integration of the available evidence. In the current study, 9 sub-groups of AOPs were reviewed, such as electrochemical, UV/H2O2 photolysis, photocatalysis, Fenton-type, plasma, gamma irradiation, sulfate-based catalyst, sonolysis and ozonation technology for organophosphorus pesticides degradation. The random effects model was used to estimate the pooled measurements and 95 % confidence intervals (95 % CI). In total, six studies were included in this review. All studies, except one, used the photocatalytic process as AOP. The average pooled percentage of AOP for pesticide degradation was 66.8 (95 % CI: 58.1–75.6). In addition, the most studied pesticides are chlorpyrifos and diazinon which, according to the results of the meta-analysis, the photocatalytic process has the highest efficiency of diazinon elimination with an average percentage of 79.2 (95 % CI: 76.8–81.5).

We report the fabrication of nitrogen-doped carbon dots-zinc oxide hybrid (NCDs-ZnO) nanostructures utilizing simple chemical procedures. The role of NCDs in ZnO nanostructured matrix has been analyzed through XRD, SEM, FTIR and PL characterization techniques. The introduction of NCDs was found to modify not only their aspect ratio, observed by a reduction in the preferredc-axis growth compared to thea- andb-axis, but also induced an additional emission around 441 nm, which is typical of NCDs. The hybrid nanostructures were utilized as catalyst for methylene blue dye degradation showing a 95% degradation after 2 h of UV irradiation in comparison to the ∼70% degradation obtained by utilizing pristine ZnO, while the dye half-life (t1/2) was reduced by ∼65% by utilizing NCDs-ZnO hybrid nanostructures when compared to the pristine ZnO. The reusability of the fabricated hybrid structures was tested up to eight times with no significant loss in their photocatalytic performance (>90%). The stability of the hybrid structures was verified through Z-potential measurements prior and after reutilization. Excellent reusability and simple processing presented by NCDs-ZnO hybrid nanostructures makes them promising for industrial level photocatalyst for the waste water treatment.

Milk-vetch (MV) and compact discs (CDs) wastes, as natural and synthetic carbonaceous precursors, were used to produce low-cost activated carbons. The efficiency of adsorption of these adsorbents was compared with commercial activated carbon (CAC) for the adsorption of bisphenol A (BPA) from aqueous solutions. The activated carbon prepared from MV (MVAC) had a higher adsorption capacity, 33.19 mg g(-1), than that of both CD wastes (CDAC), 12.15 mg g(-1), and CAC, 29.22 mg g(-1). These adsorbents were characterized using X-ray diffraction, scanning electron microscope, Brunauer-Emmett-Teller method, pH(zpc) and Fourier transform-infrared spectra techniques. The effect of operating parameters on the adsorption of BPA such as the pH, contact time, adsorbent dosages, initial BPA concentrations, temperature, and ionic strength were studied. The optimal removal of the BPA was achieved at neutral pH (pH 7) by three adsorbents. Equilibrium contact times of 90 min were achieved for all the investigated activated carbons. Based on the obtained results, the pseudo-second-order kinetic model and Langmuir isotherm fitted the experimental finding better than other isotherms and kinetics. Furthermore, thermodynamic parameters were calculated and Delta G, Delta H and Delta S indicate that the reaction is spontaneous and endothermic, and physisorption mechanism was the dominant mechanism in terms of adsorption of BPA onto the three adsorbents.

The purpose of the present work was to prepare activated carbon (AC) from low-cost wastes, such as digital versatile discs (DVDs) and compact discs (CDs), coated with carbon nanotubes (CNTs) for adsorption of Acid Orange 7 (AO7) from dye-containing solutions. The surface morphology of the activated carbons from DVDs (DVDsAC), CDs (CDsAC), CNTs, CNTs/DVDsAC and CNTs/CDsAC was determined by XRD and SEM techniques. SEM micrographs of adsorbents clearly show a heterogeneous porous surface with irregular pores in the structure of the activated carbons. Results showed that CNTs/DVDsAC (30.3 mg/g) and CNTs/CDsAC (32.8 mg/g), in comparison with DVDsAC (15.1 mg/g) and CDsAC (9.9 mg/g), were more efficient adsorbents for the adsorption of AO7. The dye adsorption amount (qe) increases with a reduction in the solution pH, adsorbent dosage and an increase in the initial concentration of AO7 for these two more efficient adsorbents. Pseudo-second order model and Langmuir isotherm fitted with the experimental data. The spontaneous and endothermic processes were analyzed by the thermodynamic studies for the adsorption of AO7. The negative values of ΔG, and the positive values of ΔH and ΔS parameters indicate that the adsorption of AO7 onto CNTs/CDsAC and CNTs/DVDsAC was spontaneous and endothermic, respectively.

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.

The performance of UVA-LEDs assisted peroxymonosulfate (PMS)/Fe2+ system was evaluated on carmoisine (E122) decolorization. Complete color removal was obtained under the conditions of pH=3.0, PMS=1.5 mM, Fe2+=1 mM and 25 min reaction time. UVA-LEDs were preferable compared to conventional UVA lamp in terms of decolorization. The functions of Co2+, Cu2+, Mn2+ and Fe2+ were compared and their results showed that Co2+ and Fe2+ had the highest efficiencies. Moreover, the presence of chloride ion showed a double role in different concentrations in which promotional effect was observed in 100 mM Cl−

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.

Chitosan (CS), synthesized from chitin chemically extracted from shrimp shells, was used for the synthesis of magnetic chitosan nanoparticles (Fe3O4-CSN), which makes the adsorbent easier to separate. Fe3O4-CSN was used for the removal of toxic metals such as vanadium (V(V)) and palladium (Pd(II)) ions from aqueous solutions. Influencing factors on the adsorption process such as pH, contact time, adsorbent dosage, and agitation speed were investigated. A competitive adsorption of V(V) and Pd(II) ions for the active sites was also studied. The monolayer maximum adsorption capacities (Qm) of 186.6 and 192.3 mg/g were obtained for V(V) and Pd(II) ions, respectively. The pseudo-second-order equation gave the best fit for the kinetic data, implying that chemisorption was the determining step. Freundlich model yielded a much better fit than the other adsorption models assessed (Langmuir, Temkin and Dubinin-Radushkevich). Thus, the adsorption of V(V) and Pd(II) ions onto Fe3O4-CSN is a combination of physical and chemical adsorption, as based on the kinetics and equilibrium study. Generally, physical adsorption is the mechanism that governs the system, while chemical adsorption is the slowest adsorption step that takes place. Thermodynamic studies displayed that the adsorption process was exothermic and spontaneous. Removal efficiencies of 99.9% for V(V) and 92.3% for Pd(II) ions were achieved, implying that Fe3O4-CSN adsorbent had an excellent ability for the removal of the metal ions from real industrial wastewaters without remarkable matrix effect.