Effect of HPLC binary mobile phase composition on the analysis of carbonyls

The relative performance of the binary mobile phase in the high-performance liquid chromatography analysis of carbonyl compounds (CCs) was tested using the liquid-phase standards containing 15 aldehyde/ketone-DNPH mixture. The Hichrome column was employed for the analysis of CCs at a flow rate of 1.5 mL min(?-?1). The binary mobile phases prepared using both acetonitrile/water (AW) and a possible alternative of methanol:water (MW) mixture were examined by their calibration results. The data derived from these two binary phases were then evaluated in terms of three key variables (i.e., resolution, relative sensitivity, and retention time). The relative water content (or the water to organic solvent ratio (W/A) or (W/M)) of the binary phase was found as the key variable for the performance. The results indicate that the optimal resolution of AW combination was attained consistently for most composition, while MW generally suffered from overpressure problem. The changes of water content in the AW mixture led to the changes of all three variables in the quantitative analysis of CCs. The obtained results confirm that the AW mixture should be the optimal elutant for the CC analysis, as other simple binary compositions like MW are limited in many respects.     

COVID-19 and the emerging research trends in environmental studies: a bibliometric evaluation

Environmental Science and Pollution Research - The ongoing pandemic of the coronavirus disease 2019 (COVID-19) is a global health emergency. Thousands of articles have been published to tackle this...     

Fatty acid fouling of forward osmosis membrane: Effects of pH, calcium, membrane orientation, initial permeate flux and foulant composition

Octanoic acid (OA) was selected to represent fatty acids in effluent organic matter (EOM). The effects of feed solution (FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmosis (FO) were investigated. The undissociated OA formed a cake layer quickly and caused the water flux to decline significantly in the initial 0.5 hr at unadjusted pH 3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated pH of 9.00. Moreover, except at the initial stage, the sudden decline of water flux (meaning the occurrence of severe membrane fouling) occurred in two conditions: 1. 0.5 mmol/L Ca^2 +, active layer facing draw solution (AL-DS) and 1.5 mol/L NaCl (DS); 2. No Ca^2 +, active layer-facing FS (AL-FS) and 4 mol/L NaCl (DS). This demonstrated that cake layer compaction or pore blocking occurred only when enough foulants were absorbed into the membrane surface, and the water permeation was high enough to compact the deposit inside the porous substrate. Furthermore, bovine serum albumin (BSA) was selected as a co-foulant. The water flux of both co-foulants was between the fluxes obtained separately for the two foulants at pH 3.56, and larger than the two values at pH 9.00. This manifested that, at pH 3.56, BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at pH 9.00, the mutual effects of OA and BSA eased the membrane fouling.     

Greenhouse gas dynamics in an urbanized river system: influence of water quality and land use

Environmental Science and Pollution Research - Rivers act as a natural source of greenhouse gases (GHGs). However, anthropogenic activities can largely alter the chemical composition and microbial...     

Impact of air pollution on outdoor cultural heritage objects and decoding the role of particulate matter: a critical review

Environmental Science and Pollution Research - Atmospheric gases and particulate matter (PM) in contact with the material’s surface lead to chemical and physical changes, which in most cases...     

Degradation characteristics of methyl ethyl ketone by Pseudomonas sp. KT-3 in liquid culture and biofilter

With ketone pollution forming an ever-growing problem, it is important to identify a ketone-degrading microorganism and establish its effect. Here, a methyl ethyl ketone (MEK)-degrading bacterium, Pseudomonas sp. KT-3, was isolated and its MEK degradation characteristics were examined in liquid cultures and a polyurethane-packed biofilter. In liquid cultures, strain KT-3 could degrade other ketone solvents, including diethyl ketone (DK), methyl propyl ketone (MPK), methyl isopropyl ketone (MIPK), methyl isobutyl ketone (MIBK), methyl butyl ketone (MBK) and methyl isoamyl ketone (MIAK). The maximum specific growth rate (mumax) of the isolate was 0.136 h(-1) in MEK medium supplemented with MEK as a sole carbon source, and kinetically, the maximum removal rate (Vm) and saturation constant (Km) for MEK were 12.28 mM g(-1)DCW h(-1) (DCW: dry cell weight) and 1.64 mM, respectively. MEK biodegradation by KT-3 was suppressed by the addition of MIBK or acetone, but not by toluene. In the tested biofilter, KT-3 exhibited a>90% removal efficiency for MEK inlet concentrations of around 500 ppmv at a space velocity (SV) of 150 h(-1). The elimination capacity of MEK was more influenced by SV than by the inlet concentration. Kinetic analysis showed that the maximum MEK removal rate (Vm) was 690 g m(-3) h(-1) and the saturation constant (Km) was 490 ppmv. Collectively, these results indicate the polyurethane sequencing batch biofilter with Pseudomonas sp. KT-3 will provide an excellent performance in the removal of gaseous MEK.     

Mineral carbonation using alkaline waste and byproducts to reduce CO2 emissions in Taiwan

Environmental Chemistry Letters - Climate change induced partly by emissions of carbon dioxide (CO2) is an urgent issue worldwide, calling for advanced methods of carbon sequestration. Since...     

New methods of life expectancy estimation

Environmental and Ecological Statistics - Two novel methods of life expectancy estimation, applied to various annual reported demographic datasets, are proposed. First, for datasets that fully...     

Health effects of PM2.5 constituents and source contributions in major metropolitan cities,South Korea

Ambient PM_2.5 is one of the major risk factors for human health, and is not fully explained solely by mass concentration. We examined the short-term associations of cause-specific mortality (i.e., all-cause, cardiovascular, and respiratory mortality) with the 15 chemical constituents and sources of PM_2.5 in four metropolitan cities of South Korea during 2014–2018. We found transition metals consistently showed significant associations with all-cause mortality, while the effects of other constituents varied across the cities and for cause of death. Carbonaceous components strongly affected the all-cause, cardiovascular, and respiratory mortality in Daejeon. Secondary inorganic aerosols, SO₄^2? and NH₄⁺, showed significant associations with respiratory mortality in Gwangju. We also found the sources from which species closely linked to mortality generally increased the relative mortality risks. Heavy metal markers from soil or industrial sources were significantly associated with mortality in all cities. However, several sources influenced mortality despite their marker species not being significantly associated with it. Secondary nitrate and secondary sulfate sources were linked to mortality in DJ. This could be attributed to the deep inland location, which might have facilitated formation of secondary inorganic aerosols. In addition, primary sources including mobile and coal combustion seemed to have acute impacts on respiratory mortality in Gwangju. Our findings suggest the necessity of positive matrix factorization (PMF)-based approaches for evaluating health effects of PM_2.5 while considering the spatial heterogeneity in the compositions and source contributions of PM_2.5.