Functional group influences on the reactive azo dye decolorization performance by electrochemical oxidation and electro-Fenton technologies

Electrochemical water treatment technologies are highly promising to achieve complete decolorization of dyebath effluents, as demonstrated by several studies reported in the literature. However, these works are focused on the treatment of one model pollutant and generalize the performances of the processes which are not transposable since they depend on the pollutant treated. Thus, in the present study, we evaluate, for the first time, the influence of different functional groups that modify the dye structure on the electrochemical process decolorization performance. The textile azo dyes Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5 have been selected because they present the same molecular basis structure with different functional groups. The results demonstrate that the functional groups that reduce the nucleophilicity of the pollutant hinder the electrophilic attack of electrogenerated hydroxyl radical. Thereby, the overall decolorization efficiency is consequently reduced as well as the decolorization rate. Moreover, the presence of an additional chromophore azo bond in the molecule enhances the recalcitrant character of the azo dyes as pollutants. The formation of a larger and more stable conjugated π system increases the activation energy required for the electrophyilic attack of ^?OH, affecting the performance of electrochemical technologies on effluent decolorization.     

Source apportionment of settleable particles in an impacted urban and industrialized region in Brazil

Environmental Science and Pollution Research - Settleable particulate matter (SPM), especially coarser particles with diameters greater than 10 μm, has been found culprit of high...     

Photochemical generation of reactive intermediates from urban-waste bio-organic substances under UV and solar irradiation

Singlet oxygen (¹O₂), hydroxyl radicals (^•OH), and excited triplet states of organic matter (³OM^*) play a key role in the degradation of pollutants in aquatic environments. The formation rates and quantum yields (Φ) of these reactive intermediates (RI) through photosensitized reactions of dissolved organic matter (DOM) have been reported in the literature for decades. Urban biowaste-derived substances (UW-BOS), a form of organic matter derived from vegetative and urban waste, have recently been shown to be efficient sensitizers in the photo-degradation of different contaminants. Nevertheless, no quantitative measurements of photo-oxidant generation by UW-BOS have been reported. In this study, the formation quantum yields of ¹O₂ and ^•OH, as well as quantum yield coefficients of TMP degradation (indicative of ³OM^* formation), were quantified for two UW-BOS samples, under 254-nm UV radiation or simulated sunlight and compared to a DOM standard from the Suwanee River (SRNOM). Values of Φ for UW-BOS samples ranged from Φ(+¹O₂) = 8.0 to 8.8 × 10⁻³, Φ(+^•OH) = 4.1 to 4.3 × 10⁻⁶, and f _TMP = 1.22 to 1.23 × 10² L Einstein⁻¹ under simulated sunlight and from Φ(+¹O₂) = 1.4 to 2.3 × 10⁻², Φ(+^•OH) = 1.3 to 3.5 × 10⁻³, and f _TMP = 3.3 to 3.9 × 10² L Einstein⁻¹ under UV. Although UW-BOS are not necessarily better than natural DOM regarding photosensitizing properties, they do sensitize the production of RI and could potentially be used in engineered treatment systems.

     

Effects of biodiesel made from swine and chicken fat residues on carbon monoxide,carbon dioxide,and nitrogen oxide emissions

The effects of two alternative sources of animal fat-derived biodiesel feedstock on CO₂, CO, NO_x tailpipe emissions as well as fuel consumption were investigated. Biodiesel blends were produced from chicken and swine fat waste (FW-1) or floating fat (FW-2) collected from slaughterhouse wastewater treatment processes. Tests were conducted in an unmodified stationary diesel engine operating under idling conditions in attempt to simulate slow traffic in urban areas. Significant reductions in CO (up to 47% for B100; FW-2) and NO_x (up to 20% for B5; FW-2 or B100; FW-1) were attained when using biodiesel fuels at the expense of 5% increase in fuel consumption. Principal component analysis (PCA) was performed to elucidate possible associations among gas (CO₂, CO, and NO_x) emissions, cetane number and iodine index with different sources of feedstock typically employed in the biodiesel industry. NO_x, cetane number and iodine index were inversely proportional to CO₂ and biodiesel concentration. High NO_x emissions were reported from high iodine index biodiesel derived especially from forestry, fishery and some agriculture feedstocks, while the biodiesel derived from animal sources consistently presented lower iodine index mitigating NO_x emissions. The obtained results point out the applicability of biodiesel fuels derived from fat-rich residues originated from animal production on mitigation of greenhouse gas emissions. The information may encourage practitioners from biodiesel industry whilst contributing towards development of sustainable animal production.

Implications: Emissions from motor vehicles can contribute considerably to the levels of greenhouse gases in the atmosphere. The use of biodiesel to replace or augment diesel can not only decrease our dependency on fossil fuels but also help decrease air pollution. Thus, different sources of feedstocks are constantly being explored for affordable biodiesel production. However, the amount of carbon monoxide (CO), carbon dioxide (CO₂), and/or nitrogen oxide (NO_x) emissions can vary largely depending on type of feedstock used to produce biodiesel. In this work, the authors demonstrated animal fat feasibility in replacing petrodiesel with less impact regarding greenhouse gas emissions than other sources.     

Field application of farmstead runoff to vegetated filter strips: surface and subsurface water quality assessment

Farmstead runoff poses significant environmental impacts to ground and surface waters. Three vegetated filter strips were assessed for the treatment of dairy farmstead runoff at the soil surface and subsurface at 0.3- or 0. 46-m and 0. 76-m depths for numerous storm events. A medium-sized Michigan dairy was retrofitted with two filter strips on sandy loam soil and a third filter strip was implemented on a small Michigan dairy with sandy soil to collect and treat runoff from feed storage, manure storage, and other impervious farmstead areas. All filter strips were able to eliminate surface runoff via infiltration for all storm events over the duration of the study, eliminating pollutant contributions to surface water. Subsurface effluent was monitored to determine the contributing groundwater concentrations of numerous pollutants including chemical oxygen demand (COD), metals, and nitrates. Subsurface samples have an average reduction of COD concentrations of 20, 11, and 85% for the medium dairy Filter Strip 1 (FS1), medium dairy Filter Strip 2 (FS2), and the small Michigan dairy respectively, resulting in average subsurface concentrations of 355, 3960, and 718 mg L COD. Similar reductions were noted for ammonia and total Kjeldahl nitrogen (TKN) in the subsurface effluent. The small Michigan dairy was able to reduce the pollutant leachate concentrations of COD, TKN, and ammonia over a range of influent concentrations. Increased influent concentrations in the medium Michigan dairy filter strips resulted in an increase in COD, TKN, and ammonia concentrations in the leachate. Manganese was leached from the native soils at all filter strips as evidenced by the increase in manganese concentrations in the leachate. Nitrate concentrations were above standard drinking water limits (10 mg L), averaging subsurface concentrations of 11, 45, and 25 mg L NO-N for FS1, FS2, and the small Michigan dairy, respectively.     

Carbon Monoxide Trend,Meteorology, and Three-Way Catalysts in Mexico City

ABSTRACT

From the analysis of data of the Inspection/Maintenance (I/M) program, and of the long-term trend of ambient CO concentrations in Mexico City, it is inferred that three-way catalysts (TWCs) have a 45% efficiency, well below the expected 90% value. The most probable causes are sulfur poisoning, lead contamination, and ceramic breakage due to bumps and potholes on the streets. Also, we have found a ratio between the average daily peak value of atmospheric CO and gasoline consumption: (11 ± 1) ppbCO/MLm (million liters of gasoline per month) in 1988 decaying to (10 ±1) in 1991 for Mexico City before the introduction of TWCs. In addition, we found a correlation between the monthly averages of CO daily peak and meteorological variables, explaining most of the seasonal changes using only the intensity of the inversion layer and surface wind speed.     

Residual tembotrione and atrazine in carrot

Carrot (Daucus carota L.) is a vegetable crop that is grown throughout the year across various regions of Brazil in rotation or in succession to other cultures. Herbicide residual effect has emerged as a concern, because of the possibility of carryover. Thus, the objective of this study was to evaluate the effect of tembotrione and atrazine residues – in mixture and isolated – on carrot planted in succession to corn. The experiment was designed in randomized blocks with five replications. Treatments consisted of tembotrione (50.4 g ha^?1), tembotrione (100.8 g ha^?1), tembotrione + atrazine (50.4 g ha^?1+ 2 L ha^?1), tembotrione + atrazine (100.8 g ha^?1+ 2 L ha^?1), and atrazine (2.00 L ha^?1) applied eight months before carrot seeding, plus a control treatment with no herbicide application. Investigated variables were shoot dry mass, productivity, and classification of carrot roots. The presence of atrazine and tembotrione decreased dry mass in the area, and only tembotrione reduced total root productivity. Thus, there is a carryover effect to tembotrione application that reduces the dry matter accumulation of shoot and total productivity, and an atrazine + tembotrione (100.8 g ha^?1) mixture reduces the total productivity after application of these herbicides to soil.     

Leaching and persistence of ametryn and atrazine in red–yellow latosol

This study evaluated the mobility and persistence of atrazine and ametryn in red–yellow latosols using polyvinyl chloride columns with a diameter of 100 mm and a height of 15 cm. The assays simulated 60-mm rainfall events at 10-day intervals for 70 days. The persistence and leaching were evaluated for these two herbicides. The analytes obtained from the samples were quantified by gas chromatography using flame ionization detection. Compared with ametryn, atrazine showed a greater potential to reach depths below 15 cm over 30 days of simulated rain. Ametryn, however, showed greater persistence in soil at 70 days after application. The persistence of atrazine and ametryn in soil under sunlight was 10 and 144 days respectively. Atrazine was more susceptible to sunlight than ametryn because sunlight favored atrazine degradation in hydroxyatrazine. The results indicate that in red–yellow latosol, atrazine has a high leaching potential in short term, but that ametryn is more persistent and has a high leaching potential in long term.     

Diquat associated with copper sources for algae control: Efficacy and ecotoxicology

The aims of this research were to evaluate the efficacy of copper oxychloride (CuCl₂.3Cu(OH)₂), copper hydroxide (Cu(OH)₂) and diquat (1.1′-ethylene-2.2′-bipyridyldiylium dibromide), isolated and in association with 0.1% of both copper sources, in the control of the unicellular algae Ankistrodesmus gracilis and the filamentous algae Pithophora kewesis, and to determine the acute toxicity of the tested chemicals in Hyphressobrycon eques, Pomacea canaliculata, Lemna minor and Azolla caroliniana. The efficacy was estimated by the methods of chlorophyll a and pheophytin a readings, changed into growth inhibition percentage. Both algae were exposed to the following concentrations: 0.2; 0.4; 0.8; 1.2 mg L^?1 of diquat and its association with the copper sources; and 0.1; 0.3; 0.5; 0.7; 1.0 and 1.5 mg L^?1 in the isolated applications of copper hydroxide and copper oxychloride. An untreated control was kept. The acute toxicity was estimatedby 50% lethal concentration (LC50). The copper sources were effective for A. gracilis control, at rates as high as 0.1 mg L^?1 (>95% efficacy). Isolated diquat and its association with copper hydroxide were both effective at rates as high as 0.4 mg L^?1, with 95 and 88% control efficacy, respectively. The copper oxychloride was effective at 0.2 mg L^?1, with 93% efficacy. None of the tested chemicals and associations was effective on P. kewesis control. The most sensitive non target organism to the tested chemicals was L. minor; the less sensitive was H. eques.     

Energy rating methodology for light-duty vehicles: geographical impact

The aim of this paper was to describe a new energy dependency score methodology and its consequent application to cars sold in twelve regions: Europe (EU-28) and eleven specific countries worldwide (Australia, Brazil, China, India, Japan, Norway, Portugal, Russia, Saudi Arabia, South Africa and USA). This methodology was developed as a potential tool to inform consumers of their choice impact on the country’s economy. This methodology is based on primary energy assessments and origins for each energy pathway associated with a gasoline-, diesel-, natural gas (used for H₂ production)- or electricity (balanced with country electricity mix)-powered vehicle. An energy dependency index was attributed to the best-case (100 % endogenous production) and worst-case (0 % endogenous production) scenarios and consequently weighted with vehicle fuel consumption. This enabled obtaining an energy dependency index (10–0). This index could be assigned to an environmental and social index to provide a sustainability index and therefore complement a road vehicle environmental rating system, providing a combined index rating. Internal combustion engine vehicles and hybrid vehicles (that have oil products as energy source) rate the lowest for almost all locations, with the exception of regions that are energy independent (Norway, Saudi Arabia or Russia). Electric vehicles rank higher when comparing to the other technologies analyzed for all locations in this study. The plug-in hybrid electric vehicle shows generally a rank in an intermediate place, except for Japan where it scores lower than all other technologies.