Thermodynamic characterization of a non-commercial emulsifying agent for asphalt emulsion

Abstract

The objective of the present work was to characterize a non-commercial emulsifying agent: dodecylpyridinium thiocyanate (C12PCNS). This study was carried out by conductimetry technique in the temperature range 25–50 °C. Assuming the system conforms to the pseudo-phase separation model, change of standard Gibbs free energy, ΔG_m ⁰, enthalpy, ΔH_m ⁰, and entropy of micellization, ΔS_m ⁰, were estimated. Values for critical micelle concentration (cmc) and the ionization degree, β, were determined directly from the experimental data. The results show that the influence of the counter ion is very relevant, because the cmc for this compound is appreciably greater than the cmc of other pyridinium homologs of the same chain length. Finally, the compensation rule for this system has been found and the compensation temperature and the intercept ΔH^*—it is an indication of the stability of the micelle—were estimated.

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Sonocatalytic degradation of rhodamine B in presence of CdS

Abstract

A novel sonocatalyst CdS was prepared by a facile precipitation method, and characterized by X-ray powder diffraction, transmission electron microscopy, UV-vis absorption spectroscopy, and photoluminescence spectroscopy. Comparative sonocatalytic degradation experiments were carried out in different conditions under ultrasonic irradiation and with rhodamine B (RhB) used as the model substrate. Results indicate that CdS is a highly active sonocatalyst. The efficiency of RhB sonodegradation in aqueous solutions within 4 h is up to 70% after the addition of CdS. Abundant •OH during the RhB sonodegradation was detected, which may be responsible for the high sonodegradation rate over CdS under ultrasonic radiation.

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Matrix effect in case of purification of oily waters by membrane separation combined with pre-ozonation

Abstract

In the present study, oil in water emulsions (c_oil = 100 ppm; d_{oil droplets} < 2 μm) was purified with ozonation followed by microfiltration using polyethersulfone (PES) membrane (d_pore = 0.2 μm). The effects of pre-ozonation on membrane microfiltration were investigated in detail both in case of ultrapure and model groundwater matrices, applying different durations (0, 5, 10, and 20 min) of pre-ozonation. Simultaneously, the effects of added inorganic water components on the combined method were investigated. Size distribution of oil droplets, zeta potentials, fluxes, and purification efficiencies were measured and fouling mechanisms were described in all cases. It was found that the matrix significantly affected the size distribution and adherence ability of oil droplets onto the membrane surface, therefore fouling mechanisms also were strongly dependent on the matrix. In case of low salt concentration, the total resistance was caused mainly by reversible resistance, which could be significantly reduced (eliminated) by pre-ozonation. In case of model groundwater matrix, nearly twice higher total resistance was measured, and irreversible resistance was dominant, because of the higher adhesion ability of the oil droplets onto the membrane surface. In this case, pre-ozonation resulted in much lower irreversible, but higher reversible resistance. Increased duration of pre-ozonation raised the total resistance and reduced the elimination efficiency (due to fragmented oil droplets and water soluble oxidation by-products) in both cases, therefore short pre-ozonation can be recommended both from economic and performance aspects.

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The environmental impact of informal and home productive arrangement in the jewelry and fashion jewelry chain on sanitary sewer system

Abstract

The outsourcing informal home practices adopted in jewelry and fashion jewelry chain can cause toxic substance elimination in the effluents and raise a concern for its environmental impact. This study evaluates if this informal work alters the concentration of potentially toxic elements (PTEs: As, Cd, Cr total and Cr-VI, Cu, Hg, Ni, Pb, Sn, and Zn) in the sewage network. The sanitary sewage samples (n = 540) were collected in 15 manholes during two campaigns in three different areas of Limeira-SP, Brazil (industrial area, with informal work and without known industrial/informal activity). The sewage sludge (n = 12), raw (n = 12), and treated sewage (n = 12) were collected in two wastewater treatment plants (WWT: AS and TATU) operating with different treatment process. The PTE determination was performed by ICP-OES, direct mercury analysis, and UV–Vis spectroscopy. Cr-VI, Cu, Ni, and Zn were the only elements above the quantification limit. Four samples exceeded Cu or Zn values permitted to be discharged into sewage system; however, the concentration average was lower than that established by Brazilian legislation. A difference was found between values above and below the 75th percentile for campaign and total organic carbon values (p < 0.015). The AS-treated sewage presented low concentrations of Cu (p < 0.05), Zn (p = 0.02), and Ni (p = 0.01) compared to treated sewage from TATU. In the sludge samples, the Cu means exceeded the limits of the Brazilian legislation (1500 mg kg⁻¹) and the Zn results were very close to the limits (2800 mg kg⁻¹). The heterogeneity of the results can indicate the sporadic nature of the PTE's sanitary disposal. PTEs used in jewelry and fashion jewelry chain may precipitate on the sludge, where presented high concentrations of Cu and Zn which require controlled destination.

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IJERPH, Vol. 15, Pages 248: Women’s Ideas about the Health Effects of Household Air Pollution, Developed through Focus Group Discussions and Artwork in Southern Nepal

IJERPH, Vol. 15, Pages 248: Women's Ideas about the Health Effects of Household Air Pollution, Developed through Focus Group Discussions and Artwork in Southern Nepal

International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15020248

Authors: Delan Devakumar Zeshan Qureshi Jenevieve Mannell Manju Baruwal Neha Sharma Eva Rehfuess Naomi M. Saville Dharma S. Manandhar David Osrin

Household air pollution is a major cause of ill health, but few solutions have been effective to date. While many quantitative studies have been conducted, few have explored the lived experiences and perceptions of women who do the cooking, and as a result are those most exposed to household air pollution. In this study, we worked with groups of home cooks, and sought to use art as a means of engaging them in discussions of how household air pollution from cooking affects their lives. In the Terai district of southern Nepal, we held four focus groups that included 26 local women from urban and peri-urban areas, as well as six local artists. The women then met approximately weekly over four months, and produced images related to air pollution. Transcripts from the focus groups were reviewed independently by two authors, who initially categorised data deductively to pre-defined nodes, and subsequently inductively reviewed emergent themes. Women identified a number of health effects from air pollution. The main physical effects related to the eye and the respiratory system, and women and young children were seen as most vulnerable. The psychosocial effects of air pollution included reduced food intake by women and lethargy. Suggested solutions included modifications to the cooking process, changing the location of stoves, and increasing ventilation. The main barriers were financial. The lived experiences of women in southern Nepal around the problem of air pollution offers a more nuanced and context-specific understanding of the perceptions and challenges of addressing air pollution, which can be used to inform future interventions.

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IJERPH, Vol. 15, Pages 247: Assessing Heat Stress and Health among Construction Workers in a Changing Climate: A Review

IJERPH, Vol. 15, Pages 247: Assessing Heat Stress and Health among Construction Workers in a Changing Climate: A Review

International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15020247

Authors: Payel Acharya Bethany Boggess Kai Zhang

Construction workers are at an elevated risk of heat stress, due to the strenuous nature of the work, high temperature work condition, and a changing climate. An increasing number of workers are at risk, as the industry's growth has been fueled by high demand and vast numbers of immigrant workers entering into the U.S., the Middle East and Asia to meet the demand. The risk of heat-related illnesses is increased by the fact that little to no regulations are present and/or enforced to protect these workers. This review recognizes the issues by summarizing epidemiological studies both in the U.S. and internationally. These studies have assessed the severity with which construction workers are affected by heat stress, risk factors and co-morbidities associated with heat-related illnesses in the construction industry, vulnerable populations, and efforts in implementing preventive measures.

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Potential health risk assessment through ingestion and dermal contact arsenic-contaminated groundwater in Jianghan Plain, China

Abstract

Groundwater contamination with high arsenic (As) levels has caused serious health problem in Jianghan Plain. This study presents a framework to evaluate the results and their probable influencing factors of non-carcinogenic risk and carcinogenic risk in Shahu Village. An appropriate health risk assessment for residents exposing to As through ingestion and dermal contact pathways is also discussed in the paper. Hazard quotient (HQ) and target cancer risk (TR) are adopted to compute the non-carcinogenic and carcinogenic effects for residents, respectively. Monte Carlo simulation technique is used to quantify the uncertainty of the risk assessment. The assessment results show that the HQs and TRs of 10-m-deep and 25-m-deep wells exhibit seasonal variations with higher values in rainy season and lower values in dry season. The HQ values exceeding 1 at the depths of 10 (from 0.09 to 23.21 m) and 25 m (from 0.29 to 130.55 m) account for 61 and 94%, respectively, which associate with the As contents distribution in the aquifer sediments. The estimated TR values at the depths of 10 (from 3.86E−05 to 1.04E−02) and 25 m (from 1.32E−04 to 5.87E−02) exceeding the highest acceptable standard (10⁻⁴) account for 95 and 100%, respectively. Comparison of the two exposure pathways, the ingestion exposure contributes much more than the dermal contact exposure for both non-carcinogenic risk and carcinogenic risk. The results of sensitivity analysis indicate that a more accurate measurement and better definition of probability distributions for As concentration in the groundwater can increase the accuracy of health risk assessment in Jianghan Plain. The findings demonstrate the importance of the drinking water safety, and the government should take measures to ensure the drinking water safety.

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