Treatment of organic pollutants by homogeneous and heterogeneous Fenton reaction processes

Nowadays, the water ecosystem is being polluted due to the rapid industrialization and massive use of antibiotics, fertilizers, cosmetics, paints, and other chemicals. Chemical oxidation is one of the most applied processes to degrade contaminants in water. However, chemicals are often unable to completely mineralize the pollutants. Enhanced pollutant degradation can be achieved by Fenton reaction and related processes. As a consequence, Fenton reactions have received great attention in the treatment of domestic and industrial wastewater effluents. Currently, homogeneous and heterogeneous Fenton processes are being investigated intensively and optimized for applications, either alone or in a combination of other processes. This review presents fundamental chemistry involved in various kinds of homogeneous Fenton reactions, which include classical Fenton, electro-Fenton, photo-Fenton, electro-Fenton, sono-electro-Fenton, and solar photoelectron-Fenton. In the homogeneous Fenton reaction process, the molar ratio of iron(II) and hydrogen peroxide, and the pH usually determine the effectiveness of removing target pollutants and subsequently their mineralization, monitored by a decrease in levels of total organic carbon or chemical oxygen demand. We present catalysts used in heterogeneous Fenton or Fenton-like reactions, such as H₂O₂–Fe³⁺(solid)/nano-zero-valent iron/immobilized iron and electro-Fenton-pyrite. Surface properties of heterogeneous catalysts generally control the efficiency to degrade pollutants. Examples of Fenton reactions are demonstrated to degrade and mineralize a wide range of water pollutants in real industrial wastewaters, such as dyes and phenols. Removal of various antibiotics by homogeneous and heterogeneous Fenton reactions is exemplified.     

Thermal, Mechanical and Rheological Behavior of Poly(lactic acid)/Talc Composites

In the present study, influence of talc on thermal, mechanical and rheological behavior of PLA is investigated and the structure?Cproperty correlation for the PLA/talc composites is established. Poly(lactic acid)/talc composites are prepared by melt mixing of PLA with talc in twin screw extruder followed by blown film processing. Various characterizations techniques are used to evaluate thermal, morphological, mechanical and rheological behavior of PLA/talc composites and its blown film. DSC analysis showed that degree of crystallinity of PLA/talc composites was higher than that of neat PLA because of nucleating ability of talc. Spherulite morphology of PLA/talc composites showed that talc has increased nucleation density of spherulite having smaller radius than that of neat PLA. Talc is effective in enhancing tensile modulus and storage modulus of PLA due to reinforcing ability of talc particles.     

Diversification of nitrogen fixing bacterial community using nifH gene as a biomarker in different geographical soils of Western Indian Himalayas

Six soil samples (Pantnagar, Chamoli, Almora, Ranichauri, Pithoragarh and Badrinath) belonging to different geographical locations of Western Himalayas in India, were analyzed to diversify the nitrogen fixing bacterial community using nifH gene biomarker DNA from soil samples were isolated and amplified using nifH gene specific primers. Genomic DNA and PCR amplified products were then individually subjected to restriction digestion with tetra to octacutter enzymes (AluI, MspI, BgIII, XbaI, HindIII, HaeIII, AluI, MspI and PasI. Further restriction pattern was studied by preparing dendograms on the basis of similarity matrix and compared for the nifH community. It was observed that temperate region soils (Ranichauri and Pithoragarh) were negative for nifH marker while subalpine region (Badrinath) and tarai region soils (Pantnagar) documented similar nifH community. Moreover; the direct genomic DNA restriction analysis indicated that subalpine region soil (Badrinath) was most diversified.     

Non-powered hand tool improvement research for prevention of work-related problems: a review

Purpose. In lower-middle-income countries, most of the work is performed manually using non-ergonomic hand tools which results in work-related health problems. Using hand tools designed in line with ergonomic principles may play an important role in reducing work-related health concerns significantly. Methods. Scientific databases (PubMed, EBSCOhost) and e-publishers were searched for articles from 1985 to 2015 using the following keywords: ‘hand tool’, ‘ergonomics’, ‘usability’ and ‘design’. After applying selection criteria to 614 articles, 58 articles related to the physical design of hand tools were selected. Results. Seventeen articles were related to hand tool improvement in the manufacturing sector. Musculoskeletal disorders were found to be the most frequently occurring work-related health problems. Most of the articles focused on product and qualitative variables for improvement in hand tools, while few articles considered human and task variables. Conclusions. Literature shows that hand tool improvement studies have been given less importance in low-income and lower-middle-income countries. However, some work of significance is reported in the agriculture sectors of these countries. Hence, it is concluded that ergonomic intervention in hand tools is much needed for those industries which employ traditional methods of working.     

Single-stage versus two-stage models to estimate creatinine corrected urinary analyte concentrations

The ability to detect 'known' differences in urinary analyte concentrations due to gender, age, and race/ethnicity when adjusted for similar differences in urinary creatinine concentrations were evaluated by a single-stage and a two-stage model by ten simulation studies. Log10 transformed values of observed urinary analyte concentration were used as the dependent variable and age, gender, and race/ethnicity were used as the categorical independent variables. In addition, while single-stage model used log10 transformed values of urinary creatinine as a covariate, two-stage model used a correction factor (CF) determined during the first stage of the model by fitting a secondary model for urinary creatinine. Single-stage model was almost always able to statistically significantly detect 'known' differences due to age, gender, and race/ethnicity. On the other hand, two-stage model was able to statistically significantly detect 'known' differences due to age, gender, and race/ethnicity a maximum of 87.2% of the times and as low as 10.6% of the times primarily because of the presence of multicollinearity between CF and urinary creatinine concentrations. Consequently, as long as the sole objective is to estimate the urinary analyte concentrations adjusted for the effect of all factors including urinary creatinine, single-stage models are the models of choice.     

Application of ameliorated wood pulp to recover Cd(II), Pb(II), and Ni(II) from e-waste

In this study, dl-malic acid and hydrogen peroxide were used as leaching agents to remove metals from e-waste (printed-circuit boards) and itaconic acid-grafted poly(vinyl alcohol)-encapsulated wood pulp (IA-g-PVA-en-WP) to uptake metals from leachate with high proficiency [11.63 mg g^?1; 93.03 % for Cd(II), 11.90 mg g^?1; 95.18 % for Pb(II), and 12.14 mg g^?1; 97.08 % for Ni(II)]. Metals were recovered from the loaded biosorbent by desorption studies. The standard analytical techniques, such as elemental analysis, Fourier-transform-infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis, were used to characterize the recovering agent (biosorbent). At equilibrium, the metal uptake data were fitted to Langmuir and D–R isotherms (R ² > 0.99) significantly, revealing, the homogeneous distribution of active sites on biosorbent’s backbone. The possible mechanism appeared to be ion exchanges of metal ions with H⁺ together with binding over functionalities (COO^?). Dimensionless equilibrium parameter (R _L) showed the favourability of metal uptake at lower concentration, while mean adsorption energy (E) certified the physical binding of metal on functionalities which was further confirmed by sticking probability and activation energy parameters. Reusability studies were also conducted to state the performance of biosorbent.     

Catalytic advancements in carbonaceous materials for bio-energy generation in microbial fuel cells: a review

Environmental Science and Pollution Research - Microbial fuel cells (MFCs) are a sustainable alternative for wastewater treatment and clean energy generation. The efficiency of the technology is...     

Human health risks in megacities due to air pollution

This study evaluates the health risks in megacities in terms of mortality and morbidity due to air pollution. A new spreadsheet model, Risk of Mortality/Morbidity due to Air Pollution (Ri-MAP), is used to estimate the excess numbers of deaths and illnesses. By adopting the World Health Organization (WHO) guideline concentrations for the air pollutants SO₂, NO₂ and total suspended particles (TSP), concentration-response relationships and a population attributable-risk proportion concept are employed. Results suggest that some megacities like Los Angeles, New York, Osaka Kobe, Sao Paulo and Tokyo have very low excess cases in total mortality from these pollutants. In contrast, the approximate numbers of cases is highest in Karachi (15,000/yr) characterized by a very high concentration of total TSP (～670 μg m^?3). Dhaka (7000/yr), Beijing (5500/yr), Karachi (5200/yr), Cairo (5000/yr) and Delhi (3500/yr) rank highest with cardiovascular mortality. The morbidity (hospital admissions) due to Chronic Obstructive Pulmonary Disease (COPD) follows the tendency of cardiovascular mortality. Dhaka and Karachi lead the rankings, having about 2100/yr excess cases, while Osaka-Kobe (～20/yr) and Sao Paulo (～50/yr) are at the low end of all megacities considered. Since air pollution is increasing in many megacities, and our database of measured pollutants is limited to the period up to 2000 and does not include all relevant components (e.g. O₃), these numbers should be interpreted as lower limits. South Asian megacities most urgently need improvement of air quality to prevent excess mortality and morbidity due to exceptionally high levels of air pollution. The risk estimates obtained from Ri-MAP present a realistic baseline evaluation for the consequences of ambient air pollution in comparison to simple air quality indices, and can be expanded and improved in parallel with the development of air pollution monitoring networks.     

Assessment of indoor air concentrations of VOCs and their associated health risks in the library of Jawaharlal Nehru University,New Delhi

The present work investigated the levels of total volatile organic compounds (TVOC) and benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX) in different microenvironments in the library of Jawaharlal Nehru University in summer and winter during 2011–2012. Carcinogenic and non-carcinogenic health risks due to organic compounds were also evaluated using US Environmental Protection Agency (USEPA) conventional approaches. Real-time monitoring was done for TVOC using a data-logging photo-ionization detector. For BTEX measurements, the National Institute for Occupational Safety and Health (NIOSH) standard method which consists of active sampling of air through activated charcoal, followed by analysis with gas chromatography, was performed. Simultaneously, outdoor measurements for TVOC and BTEX were carried out. Indoor concentrations of TVOC and BTEX (except benzene) were higher as compared to the outdoor for both seasons. Toluene and m/p-xylene were the most abundant organic contaminant observed in this study. Indoor to outdoor (I/O) ratios of BTEX compounds were generally greater than unity and ranged from 0.2 to 8.7 and 0.2 to 4.3 in winter and summer, respectively. Statistical analysis and I/O ratios showed that the dominant pollution sources mainly came from indoors. The observed mean concentrations of TVOC lie within the second group of the Molhave criteria of indoor air quality, indicating a multifactorial exposure range. The estimated lifetime cancer risk (LCR) due to benzene in this study exceeded the value of 1?×?10^?6 recommended by USEPA, and the hazard quotient (HQ) of non-cancer risk came under an acceptable range.