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Micro(nano)plastic (MNP) pollutants have not only impacted human health directly, but are also associated with numerous chemical contaminants that increase toxicity in the natural environment. Most recent research about increasing plastic pollutants in natural environments have focused on the toxic effects of MNPs in water, the atmosphere, and soil. The methodologies of MNP identification have been extensively developed for actual applications, but they still require further study, including on-site detection. This review article provides a comprehensive update on the facile detection of MNPs by Raman spectroscopy, which aims at early diagnosis of potential risks and human health impacts. In particular, Raman imaging and nanostructure-enhanced Raman scattering have emerged as effective analytical technologies for identifying MNPs in an environment. Here, the authors give an update on the latest advances in plasmonic nanostructured materials-assisted SERS substrates utilized for the detection of MNP particles present in environmental samples. Moreover, this work describes different plasmonic materials-including pure noble metal nanostructured materials and hybrid nanomaterials-that have been used to fabricate and develop SERS platforms to obtain the identifying MNP particles at low concentrations. Plasmonic nanostructure-enhanced materials consisting of pure noble metals and hybrid nanomaterials can significantly enhance the surface-enhanced Raman scattering (SERS) spectra signals of pollutant analytes due to their localized hot spots. This concise topical review also provides updates on recent developments and trends in MNP detection by means of SERS using a variety of unique materials, along with three-dimensional (3D) SERS substrates, nanopipettes, and microfluidic chips. A novel material-assisted spectral Raman technique and its effective application are also introduced for selective monitoring and trace detection of MNPs in indoor and outdoor environments.

In this study, semi-volatile organic compounds (SVOCs) in samples of indoor dust and organic thin films obtained from 100 residential houses in South Korea, were examined, based on both target analysis using gas chromatography-mass spectrometry (GC-MS) and non-target analysis by gas chromatography-quadrupole time-of flight mass spectrometry (GC-QTOF-MS) screening. In the targeted approach, phthalates and polycyclic aromatic hydrocarbons (PAHs) were analyzed in dust and organic film samples, to find that both these classes of SVOCs were detected in dust and organic film samples, with the median concentrations of eight phthalates (Σ

A porous photocatalyst concrete filter (deNOx PCF) is successfully manufactured to reduce NOx by mixing TiO2 photocatalyst with lightweight aerated concrete. From the results, 4% infusion rate of each foaming agent provided the smallest change of the height, and the optimal quality of the air bubbles can be produced by using foaming agent B with 4% of infusion rate. When 3% of TiO2 photocatalyst was mixed, less irregular and relatively homogeneous pores were formed on the surface with white color due to the proper amount of photocatalyst applied. For 3% of photocatalyst mixed with deNOx PCF, 1.03 μmol/hr of NO was reduced equivalent to 10.99% of NO reduction, suggesting that the TiO2 photocatalyst dispersed in the continuous and well-developed pores inside the specimen successfully performed the removal of NO flowing through deNOx PCF using synergistic effects of adsorption and photodegradation reaction. Finally, the specimen of porous deNOx PCF for reducing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.

To estimate greenhouse gas (GHG) emissions and degradation rate constants (kobs) from H2O2/UV-C, TiO2/UV-C, and ozonation processes in the degradation of bisphenol A (BPA), the laboratory scale experiments were conducted. In the H2O2/UV-C process, the fastest degradation rate constant (kobs = 0.353 min−1) was observed at 4 mM of H2O2, while the minimum GHG emission was achieved at 3 mM of H2O2. In the TiO2/UV-C process, the fastest rate constant (kobs = 0.126 min−1) was achieved at 2000 mg/L of TiO2, while the minimum GHG emission was observed at 400 mg/L of TiO2. In the ozonation process, GHG emissions were minimal at 5 mg/L of O3, but the degradation rate constant kept on increasing as the O3 concentration increased. There were three major types of GHG emissions in the advanced oxidation processes (AOPs). In the ozonation process, most of the GHG emissions were generated by electricity consumption. TiO2/UV-C process accounted for a significant portion of the GHGs generated by the use of chemicals. Finally, the H2O2/UV-C process produced similar GHG emissions from both chemical inputs and electricity consumption. The carbon footprint calculation revealed that for the treatment of 1 m3 of water contaminated with 0.04 mM BPA, the H2O2/UV-C process had the smallest carbon footprint (0.565 kg CO2 eq/m3), followed by the TiO2/UV-C process (3.445 kg CO2 eq/m3) and the ozonation process (3.897 kg CO2 eq/m3). Our results imply that the increase in removal rate constant might not be the optimal parameter for reducing GHG emissions during the application of these processes.

This study examined the abundance of microplastics (MPs) in 106 fish from 22 species inhabiting three sites of the Han River, South Korea. In total, 1753 MPs from 106 fish samples were identified with an average abundance of 15.60 ± 13.45 MPs per individual fish (MPs indiv

The purpose of this study was to analyze the effect of titanium dioxide (TiO2) on reducing nitrogen oxide (NOx) concentrations using the statistical method of the Anderson-Darling test. To compare and analyze this effect, a spray-type form of TiO2 was applied to the asphalt pavement surface on urban roads. Data acquisition for NOx concentration was collected from a test section with TiO2 applied and a reference section without TiO2 applied. The probabilities of occurrence of the NOx concentration in the test and reference section were estimated and compared using the Anderson-Darling test. In sum, most of the NOx concentrations were probabilistically lower in the test section. The average probability of the NOx concentration in the test section in the ‘low’ range was 46.2% higher than in the reference section. In the ‘high’ and ‘moderate’ ranges, the average probability of the NOx concentration compared to that of the reference section was lower by 28.1% and 18.8%, respectively. These results revealed that the photochemical reaction from the TiO2 material applied on asphalt pavement was effective in reducing NOx.

Understanding liquid evaporation on surfaces is of utmost importance due to its impact on a plethora of industrial and natural processes. Over the past several decades, through chemical functionalization or surface structuring, wetting and non-wetting surfaces have been extensively developed and studied in an attempt to control liquid–surface interactions. More recently, surfaces with wettability patterns comprising of local wetting/non-wetting regions have received considerable attention. Although quantitative analytical models in parallel with scaling arguments have been developed to predict and understand liquid droplet evaporation on such micro-structured surfaces, consensus in the wider community is sparse. Developing a better understanding of the evaporation performance on structured surfaces is imperative for selecting optimal structure length scales and designs for specific applications. Here, we develop dual wettability or biphilic micropillar surfaces having various dimensions by utilizing lift-off microfabrication. We focus on studying the evaporation dynamics of sessile water droplets on such micropillared biphilic as well as hydrophobic surfaces. We start by investigating the evaporation of water droplets having a wide range of diameter ( $$100

The present study investigated the photodegradation of synthetic organic dye; violet-3B, without and with the addition of C-N-codoped TiO2 catalyst using a visible halogen-lamp as a light source. The catalyst was synthesized by using a peroxo sol-gel method with free-organic solvent. The effects of initial dye concentration, catalyst dosage, and pH solution on the photodegradation of violet-3B were examined. The efficiency of the photodegradation process for violet-3B dye was higher at neutral to less acidic pH. The kinetics reaction rate of photodegradation of violet-3B dye with the addition of C-N-codoped TiO2 followed pseudo-first order kinetics represented by the Langmuir-Hinshelwood model, and increasing the initial concentration of dyes decreased rate constants of photodegradation. Photodegradation of 5 mg L-1 violet-3B dye achieved 96% color removal within 240 min of irradiation in the presence of C-N-codoped TiO2 catalyst, and approximately 44% TOC was removed as a result of the mineralization.

This study presents a promising approach that enhances the sludge fermentation by using basic oxygen furnace (BOF) slag as an alkaline source for the first time. BOF slag added to the reactors could maintain a stable alkaline condition due to continuous release of Ca(OH)2 from slag. The reactor pH could be adjusted to a target value by the choice of the BOF slag dose. Concentrations of soluble chemical oxygen demand (sCOD) and short-chain carboxylates (SCCs) were substantially increased in the presence of BOF slag. At a BOF slag mass to sludge volume ratio of 1/10 g slag/L sludge, the reactor pH was maintained at 10 and the concentration of SCCs produced was the highest (i.e., 3510 mg COD L−1 from 14,000 mg VS L−1 of sludge mixture), followed by B/S ratios of 1/20, 1.50, 1/5, and 1/2.5 g slag L−1 sludge with reactor pH of 9.4, 8.9, 10.5, and 11, respectively. Our data suggest that the pH value that best facilitates the degradation of sludge into SCCs and inhibit the conversion of SCCs into biogas is around 10. Interestingly, compositions of the accumulated SCCs varied greatly depending on the BOF slag dose. BOF slag showed phosphorus removal ability due to enhanced precipitation of Ca-PO43--P complexes, which significantly lowered PO43− concentration of the reactor effluent.

In this study, the removal kinetics and degradation mechanism of 1H-benzotriazole (BTA), which is widely used in anti-corrosive agents, during the UV/chlorination reaction were investigated, focusing on the UV-A/chlorination process. The UV-A/chlorination reaction showed a synergetic effect on the removal of BTA compared to UV-A photolysis or chlorination alone. The synergetic effect was due to the generation of hydroxyl radicals and reactive chlorine species. The removal of BTA during UV/chlorination followed pseudo-first-order kinetics. Faster removal of BTA was achieved when the chlorine dosage was increased. Alkaline pH favored the removal of BTA during UV-A/chlorination. The UV/chlorination of BTA achieved approximately 50% mineralization confirmed by total organic carbon within 12 h. As byproducts, formate and nitrate ions and five organic byproducts (m/z = 150.0307, 166.0252, 124.0147, 140.0071, and 154.0245) were identified by ion chromatography and LC-qTOF-MS. Based on the identified byproducts, we proposed the degradation pathway of BTA during the UV-A/chlorination reaction. Finally, toxicity test was performed during the UV-A/chlorination of BTA using a Microtox bioassay. The toxicity decreased during UV-A/chlorination of BTA, implying that the byproducts are less toxic than BTA. Our study indicates that the UV-A/chlorination process is effective not only in eliminating BTA, but also in decreasing toxicity.

To investigate the seasonal distribution of mercury (Hg) in precipitation in Seoul, Korea, event based total mercury (THg) and methyl mercury (MeHg) in precipitation samples were collected for one year. During sampling periods, volume weighted mean (VWM) concentration of THg and MeHg were 16.91 and 0.042 ng L−1, and wet deposition flux of THg and MeHg was 5.96 and 0.01 μg m−2, respectively. The proportion of MeHg in THg in the rainwater ranged from 0.01% to 2.22% with a mean value of 0.5%. The THg and MeHg concentration in precipitation was the highest in the winter, while wet deposition flux of THg and MeHg were highest in summer. There were significant negative correlations between THg and rain amount (p = 0.034), and between MeHg and the rain amount (p = 0.023), indicating that Hg concentrations in precipitation decreased as the amount of precipitation increased, especially in summer. THg concentration was higher when precipitation amount in one event was less than 20 mm, implying that 20 mm of precipitation can be a threshold value showing the Hg wash-out effect from the atmosphere. A significant correlation was observed between THg and NO3− (r2 = 0.65) and Cl− ion (r2 = 0.60), and between MeHg and SO42− ion (r2 = 0.52) concentrations in precipitation. We also found a weak relationship between MeHg and DOC concentrations in precipitation.

This study assessed the effects of hot water, acid, and alkali pretreatments on the lignocellulosic composition of rice straw and methane production potential of the pretreated solids-reagent mixture. Autoclaving (121 °C, 1.45 atm, 60 min) after addition of 2% H2SO4 showed the highest lignocellulose decomposition efficiency of 65.4%. However, the methane production potential was even smaller than that of the untreated sample, indicating the inhibitory effect of the acid in the biogas production process. On the other hand, hot water- and alkali-pretreated samples showed a factor of 2.1 greater methane production potential than untreated sample despite the relatively lower lignocellulose decomposition efficiency of 17.0–50.4%. By simply keeping the rice straw immersed in water at 100 °C for 30–60 min. or autoclaving prior to anaerobic digestion, the methane production potential of 805.8–824.2 mL of CH4/g total carbon and the overall lignocellulose degradability of 73.6–84.4% was achieved. The results of this study show the potential of hot water pretreatment as an efficient, chemical-free method to improve the feasibility of methane production from rice straw.

Hydrophilic solid surfaces having low contact angle hysteresis can induce stable dropwise condensation., Droplet nucleation and condensation are ubiquitous phenomena in nature and industry. Over the past century, research has shown dropwise condensation heat transfer on nonwetting surfaces to be an order of magnitude higher than filmwise condensation heat transfer on wetting substrates. However, the necessity for nonwetting to achieve dropwise condensation is unclear. This article reports stable dropwise condensation on a smooth, solid, hydrophilic surface (θa = 38°) having low contact angle hysteresis (

In this study, the effects of natural water components (nitrate, carbonate/bicarbonate, and humic acid) on the kinetics and degradation mechanisms of bisphenol A (BPA) during UV-C photolysis and UV/H2O2 reaction were examined. The presence of NO3− (0.04–0.4 mM) and CO32−/HCO3− (0.4–4 mM) ions increased BPA degradation during UV photolysis. Humic acid less than 3 mg/L promoted BPA degradation, but greater than 3 mg/L of humic acid inhibited BPA degradation. During the UV/H2O2 reaction, all water matrix components acted as radical scavengers in the order of humic acid > CO32−/HCO3− > NO3−. All of the degradation reactions agreed with the pseudo-first-order kinetics. While eight byproducts (m/z = 122, 136, 139, 164, 181, 244, 273, 289) were identified in UV-C/NO3− photolysis reaction, four (m/z = 122, 136, 164, 244) and three byproducts (m/z = 122, 136, 164) were observed during UV-C/NO3−/CO32−/HCO3− and UV-C/CO32−/HCO3− reactions. Nitrogenated and hydrogenated byproducts were first observed during the UV-C/NO3− photolysis, but only hydrogenated byproducts as adducts were detected during the UV-C/NO3−/CO32−/HCO3− photolysis. Nitrogenated and hydrogenated byproducts were formed in the early stage of degradation by OH or NO2 radicals, and these byproducts were subsequently degraded into smaller compounds with further reaction during UV-C/NO3− and UV-C/NO3−/CO32−/HCO3− reactions. In contrast, BPA was directly degraded into smaller compounds by β-scission of the isopropyl group by CO3−/HCO3 radicals during UV-C/CO32−/HCO3− reaction. Our results imply that the water components can change the degradation mechanism of BPA during UV photolysis.

This work investigated the photodegradation of azo dye, methyl orange, without and with the addition of C-N-codoped TiO2 catalyst using a visible halogen-lamp as a light source. C-N-codoped TiO2 was prepared by free-organic solvent peroxo sol-gel method. The effects of initial dye concentration, catalyst dosage, and pH solution on the photodegradation of methyl orange were studied. Photodegradation process for methyl orange solution at acidic condition showed high removal percentage. 5 mg L-1 methyl orange achieved color removal until 94% for 180 min irradiation in photodegradation process with the presence of C-N-codoped TiO2 catalyst, and approximately 70% TOC removed as the results of mineralization process. The kinetics reaction rate of photodegradation of methyl orange dye with the addition of C-N-codoped TiO2 followed pseudo-first order represented by Langmuir-Hinshelwood model, the kinetics constant of photodegradation became higher by decreasing the initial concentration of methyl orange. Three organic byproducts of methyl orange formed during photodegradation process was identified by LC-MS/MS system then degradation pathway of methyl orange photodegradation in the presence of C-N-codoped TiO2 catalyst was proposed.

In this study, the kinetics and removal mechanism of anatoxin-a (C10H15NO) during a UV-C/H2O2 reaction were investigated. The removal of anatoxin-a was more effective during a UV-C/H2O2 reaction than with either UV photolysis or H2O2 alone, due to the effective production of hydroxyl (OH) radicals. The UV-C/H2O2 reaction of anatoxin-a resulted in an approximately 60% decrease in total organic carbon (TOC) within 420 min, while 45% of the carbon in anatoxin-a was converted into acetate, and most of the nitrogen in anatoxin-a was converted into NH4+, NO2−, and NO3− ions. More than 50% of the nitrogen in anatoxin-a was mineralized, mainly into NO3− ions, and complete nitrogen recovery was achieved after 120 min of the UV-C/H2O2 reaction. Using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), we identified six degradation by-products in the UV-C/H2O2 reaction ([M+H]+ = 142, 127, 113, 132, 117, and 124, respectively), which were further degraded as the reaction continued. Using these by-products, we proposed a degradation pathway for anatoxin-a during the UV-C/H2O2 reaction. Our results indicate that anatoxin-a can be effectively removed by a UV-C/H2O2 reaction during water treatment processes.

The aim of this work was to study the effect of the differential development of microbe-substrate aggregates at different mixing intensities on the performance of anaerobic digestion of rice straw. Batch and semi-continuous reactors were operated for up to 50 and 300days, respectively, under different mixing intensities. In both batch and semi-continuous reactors, minimal mixing conditions exhibited maximum methane production and lignocellulose biodegradability, which both had strong correlations with the development of microbe-substrate aggregates. The results implied that the aggregated microorganisms on the particulate substrate played a key role in rice straw hydrolysis, determining the performance of anaerobic digestion. Increasing the mixing speed from 50 to 150rpm significantly reduced the methane production rate by disintegrating the microbe-substrate aggregates in the semi-continuous reactor. A temporary stress of high-speed mixing fundamentally affected the microbial communities, increasing the possibility of chronic reactor failure.

The removal and degradation pathways of microcystin-LR (MC-LR, [M+H]+ = 995.6) in UV-B photolysis and UV-B/H2O2 processes were examined using liquid chromatography-tandem mass spectrometry. The UV/H2O2 process was more efficient than UV-B photolysis for MC-LR removal. Eight by-products were newly identified in the UV-B photolysis ([M+H]+ = 414.3, 417.3, 709.6, 428.9, 608.6, 847.5, 807.4, and 823.6), and eleven by-products were identified in the UV-B/H2O2 process ([M+H]+ = 707.4, 414.7, 429.3, 445.3, 608.6, 1052.0, 313.4, 823.6, 357.3, 245.2, and 805.7). Most of the MC-LR by-products had lower [M+H]+ values than the MC-LR itself during both processes, except for the [M+H]+ value of 1052.0 during UV-B photolysis. Based on identified by-products and peak area patterns, we proposed potential degradation pathways during the two processes. Bond cleavage and intramolecular electron rearrangement by electron pair in the nitrogen atom were the major reactions during UV-B photolysis and UV-B/H2O2 processes, and hydroxylation by OH radical and the adduct formation reaction between the produced by-products were identified as additional pathways during the UV-B/H2O2 process. Meanwhile, the degradation by-products identified from MC-LR during UV-B/H2O2 process can be further degraded by increasing H2O2 dose.

Greenhouse gas (GHG) emission factors previously reported from various waste incineration plants have shown significant variations according to country-specific, plant-specific, and operational conditions. The purpose of this study is to estimate GHG emissions and emission factors at nine incineration facilities in Korea by measuring the GHG concentrations in the flue gas samples. The selected incineration plants had different operation systems (i.e., stoker, fluidized bed, moving grate, rotary kiln, and kiln & stoker), and different nitrogen oxide (NOx) removal systems (i.e., selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR)) to treat municipal solid waste (MSW), commercial solid waste (CSW), and specified waste (SW). The total mean emission factors for A and B facilities for MSW incineration were found to be 134 ± 17 kg CO2 ton-1, 88 ± 36 g CH4 ton-1, and 69 ± 16 g N2O ton-1, while those for CSW incineration were 22.56 g CH4 ton-1 and 259.76 g N2O ton-1, and for SW incineration emission factors were 2959 kg CO2 ton-1, 43.44 g CH4 ton-1 and 401.21 g N2O ton-1, respectively. Total emissions calculated using annual incineration for MSW were 3587 ton CO2-eq yr-1 for A facility and 11,082 ton CO2-eq yr-1 for B facility, while those of IPCC default values were 13,167 ton CO2-eq yr-1 for A facility and 32,916 ton CO2-eq yr-1, indicating that the emissions of IPCC default values were estimated higher than those of the plant-specific emission factors. The emission of CSW for C facility was 1403 ton CO2-eq yr-1, while those of SW for D to I facilities was 28,830 ton CO2-eq yr-1. The sensitivity analysis using a Monte Carlo simulation for GHG emission factors in MSW showed that the GHG concentrations have a greater impact than the incineration amount and flow rate of flue gas. For MSW incineration plants using the same stoker type in operation, the estimated emissions and emission factors of CH4 showed the opposite trend with those of NO2 when the NOx removal system was used, whereas there was no difference in CO2 emissions.

Micropollutants are often discharged to surface waters through untreated wastewater from sewage treatment plants and wastewater treatment plants. The presence of micropollutants in surface waters is a serious concern because surface water is usually provided to water treatment plants (WTP) to produce drinking water. Many micropollutants can withstand conventional WTP systems and stay in tap water. In particular, pharmaceuticals and endocrine disruptors are examples of micropollutants that are detected at the drinking water, ppb, or even ppb level. A variety of techniques and processes, especially advanced oxidation processes, have been applied to remove micropollutants from water to control drinking water contamination. This paper reviews recent researches on the occurrence and removal of micropollutants in the aquatic environments and during water treatment processes.

Seasonal and spatial variations in per- and polyfluoroalkyl substances (PFAS) concentrations in different environmental media in the Asan Lake area of South Korea were investigated by measuring liquid chromatography-tandem mass spectrometry (LC–MS/MS). The mean concentrations of Σ16 PFAS in the different media were in the ranges of 20.7–98.2 pg/m3 in air, 17.7–467 ng/L in water, 0.04–15.0 ng/g dry weight (dw) in sediments, and not detected (n.d.)–12.9 ng/g dw in soils, and the mean concentrations of Σ19 PFAS in fish ranged from n.d. to 197 ng/g wet weight. The most frequently detected PFAS were perfluorooctanoic acid (PFOA) in air and soils, perfluoropentanoic acid (PFPeA) in water, and perfluorooctane sulfonate (PFOS) in sediment and fish. Long-chain PFAS species dominated over short-chain PFAS in most media samples except for the water phase. Sediment-water partition coefficients (log Kd) and bioaccumulation factors (log BAF) of PFAS were calculated using measured concentrations in water, sediments, and fish. Log Kd of PFAS tended to increase with increasing CF2 units of PFAS, and perfluorodecanoic acid (PFDA) and PFOS showed the highest log BAF value (> 3.0) in all fish species. These results indicate that longer-chain PFAS, especially PFOS, can be effectively accumulated in biota such as fish.

This study investigated the occurrence and removals of micropollutants in the sewage treatment tank (STT) which is a typical private wastewater treatment facility used in the rural communities in Korea, and their impact on receiving water. STTs were selected in eight provinces to examine the regional difference in the composition of micropollutant occurrence. We measured ten selected micropollutants in influents and effluents of STTs, as well as upstream and downstream of its receiving surface water. The dominant micropollutants in the influent of the STTs were caffeine (13,346 ng/L), acetaminophen (11,331 ng/L), ibuprofen (1440 ng/L), and naproxen (1313 ng/L), in agreement with the amounts produced annually in Korea. In the effluent, caffeine (1912 ng/L), acetaminophen (1586 ng/L), naproxen (475 ng/L), and ibuprofen (389 ng/L) were detected in relatively high concentrations. The composition of micropollutants in STT influents showed little regional variation by provinces, suggesting that the consumption pattern of these micropollutants did not show regional variation. The removal efficiencies of the selected micropollutants at the STTs ranged from 12% (carbamazepine) to 88% (acetaminophen), lower than typical removal by sewage treatment plants (STPs). This result is probably due to the automatic operation systems and simple treatment processes in STTs compared with STPs. The concentrations of selected micropollutants upstream of the receiving water were generally lower compared with those observed downstream, indicating that effluent from STTs was the main source. The per capita discharge loads of STTs and annual emissions rates (kg/year) from private wastewater treatment facilities were estimated for the selected micropollutants.

We prepared novel Raman substrates for the sensitive detection of submicron-sized plastic spheres in water. Anisotropic nanostar dimer-embedded nanopore substrates were prepared for the efficient identification of submicron-sized plastic spheres by providing internal hot spots of electromagnetic field enhancements at the tips of nanoparticles. Silver-coated gold nanostars (AuNSs@Ag) were inserted into anodized aluminum oxide (AAO) nanopores for enhanced microplastic (MP) detection. We found that surface-enhanced Raman scattering (SERS) substrates of AuNSs@Ag@AAO yielded stronger signals at the same weight percentages for polystyrene MP particles with diameters as small as 0.4 μm, whereas such behaviors could not be observed for larger MPs (diameters of 0.8 μm, 2.3 μm, and 4.8 μm). The detection limit of the submicrometer-sized 0.4 μm in our Raman measurements were estimated to be 0.005% (∼0.05 mg/g =50 ppm) along with a fast detection time of only a few min without any sample pretreatments. Our nano-sized dimensional matching substrates may provide a useful tool for the application of SERS substrates for submicrometer MP pollutants in water.

Bacterial synthesis of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) copolymer [P(3HB-co-3HV)] using the hydrolysate of rice straw waste as a carbon source was affected by the composition of the hydrolysate, which depends highly on the rice straw pretreatment condition. Acid digestion with 2 % sulfuric acid generated larger production of P(3HB-co-3HV) than 6 % sulfuric acid, but 3HV concentration in the copolymer produced with 2 % acid hydrolysate was only 8.8 % compared to 18.1 % with 6 % acid hydrolysate. To obtain a higher 3HV mole fraction for enhanced flexibility of the copolymer, an additional heating was conducted with the 2 % acid hydrolysate after removal of residual rice straw. As the additional heating time increased a higher concentration of levulinic acid was generated, and consequently, the mole fraction of 3HV in P(3HB-co-3HV) increased. Among the conditions tested (i.e., 20-, 40-, 60-min), 60-min additional heating following 2 % sulfuric acid digestion achieved the highest 3HV mole fraction of 22.9 %. However, a longer heating time decreased the P(3HB-co-3HV) productivity, probably due to the increased intermediates concentrations acting as inhibitors in the hydrolysates. Therefore, the use of additional heating needs to consider both the increase in the 3HV mole fraction and the decrease in the P(3HB-co-3HV) productivity.

Water vapor condensation on superhydrophobic surfaces has received much attention in recent years because of its ability to shed water droplets at length scales 3 decades smaller than the capillary length (∼1 mm) via coalescence-induced droplet jumping. Jumping-droplet condensation has been demonstrated to enhance heat transfer, anti-icing, and self-cleaning efficiency and is governed by the theoretical inertial-capillary scaled jumping speed (U). When two droplets coalesce, the experimentally measured jumping speed (Uexp) is fundamentally limited by the internal fluid dynamics during the coalescence process (Uexp0.23U). Here, we theoretically and experimentally demonstrate multidroplet (2) coalescence as an avenue to break the two-droplet speed limit. Using side-view and top-view high-speed imaging to study more than 1000 jumping events on a copper oxide nanostructured superhydrophobic surface, we verify that droplet jumping occurs as a result of three fundamentally different mechanisms: (1) coalescence between two droplets, (2) coalescence among more than two droplets (multidroplet), and (3) coalescence between one or more droplets on the surface and a returning droplet that has already departed (multihop). We measured droplet-jumping speeds for a wide range of droplet radii (5-50 μm) and demonstrated that while the two-droplet capillary-to-inertial energy conversion mechanism is not identical to that of multidroplet jumping, speeds above the theoretical two-droplet limit (0.23U) can be achieved. However, we discovered that multihop coalescence resulted in drastically reduced jumping speeds (≪0.23U) due to adverse momentum contributions from returning droplets. To quantify the impact of enhanced jumping speed on heat-transfer performance, we developed a condensation critical heat flux model to show that modest jumping speed enhancements of 50% using multidroplet jumping can enhance performance by up to 40%. Our results provide a starting point for the design of enhanced-performance jumping-droplet surfaces for industrial applications.

Permissible soil concentrations for explosives (i.e., TNT and RDX) and heavy metals (i.e., Cu, Zn, Pb, and As) heve beenderived from human risk and ecotoxicity, respectively. For TNT and RDX, human risk based-permissible soilconcentrations were determined as 460 mg-TNT/kg-soil and 260 mg-RDX/kg-soil. Ecotoxicity based-permissible soilconcentrations for Cu and Zn were determined from species sensitivity distribution (SSD) and uncertainty factor of 1 to 5,yielding 18.0-40.0 mg-Cu/kg-soil and 46.0-100 mg-Zn/kg-soil. For Pb and As, ecotoxicity data were not enough toestablish SSD so that a deterministic method was used, generating 13.8-30.8 mg-Pb/kg-soil and 2.10-4.60 mg-As/kg-soil.It is worth noting that the methodology used to derive permissible concentrations in soil can differ depending onecotoxicity data availability and socio-economic situations, which results in different permissible concentrations. Thepermissible concentrations presented in this study have been derived from conservative assumptions for exposureparameters, and thus should be considered as soil standards. In the light of remediation and pollution management of a siteof interest, the site-specific and receptor-specific permissible soil concentrations should be derived considering potentialreceptors, current and future land use, background concentrations, and socio-economic consultation. Key words : Permissible soil concentration, Explosive, Heavy metal, Firing range

In this study, the electrocoagulation of perfluorooctanoic acid (PFOA) in water using an iron (Fe) electrode was investigated. The effects of the current density, stirring speed, and electrolyte concentration (NaCl) on the corresponding removal rates of PFOA were examined. An increase in the current density from 2.4 to 80.0 mA cm−2 led to a significant increase in the removal efficiency of PFOA from 10.0 to 100.0% within 6 h. Formate (HCOO−) ions and three shorter-chain perfluorocarboxylates (i.e., perfluoropentanoic acid; PFPeA, perfluorohexanoic acid; PFHxA, and perfluoroheptanoic acid; PFHpA) were observed as organic byproducts during the electrocoagulation of PFOA, indicating that the C-C bond between C7F15 was first broken down and then was degraded into short carbon-chain compounds by PFOA decomposition. 65% of fluorine recovery as fluoride ions and organic fluorine in shorter-chain byproducts (PFPeA, PFHxA, and PFHpA) with 60% of total organic carbon (TOC) removal was achieved within 6 h during electrocoagulation, while the complete removal of PFOA was achieved. Our results imply that electrocoagulation using Fe electrode can effectively degrade PFOA into shorter-chain byproducts with significant mineralization.

Benzophenone-3 (BP3) is a potential phenolic endocrine disrupter that is widely used as a sunscreen and ultraviolet (UV) stabilizer. The degradation of BP3 in water during chlorination and UV/chlorination reactions was investigated. The degradation of BP3 by both reactions followed pseudo-first-order kinetics. The pH profile of the observed pseudo-first-order rate constants (kobs) were bell shapes that depended on pH, and the highest kobs values were obtained at pH 8 for both reactions. The contribution of OH radicals ( OH) on BP3 degradation under UV/chlorination conditions increased at acidic pH values, and the contribution of reactive chlorine species (RCS) such as Cl increased at neutral and basic pH values. The BP3 degradation rate was enhanced by the presence of HCO3− ions, but was inhibited by humic acid. A total of seven transformation products (TPs) of BP3 were identified during chlorination (TP-262, TP-296, TP-192, TP-226, and TP-118) and UV/chlorination (TP-244, TP-262, TP-278, and TP-296) reactions. Among the TPs, chloroform (TP-118) was only found in the chlorination reaction. The BP3 degradation pathways during both reactions were proposed based on these TPs. Degradation of BP3 was mainly associated with electrophilic aromatic halogenation in both reactions. Finally, the bioluminescence inhibition of Vibrio fischeri by the TPs produced from the BP3 during the UV/chlorination reaction was lower than that of the TPs obtained during chlorination, implying that the additional oxidation of BP3 occurs by the reactive radicals produced during the UV/chlorination reaction.

In this study, the effects of natural water components (nitrate, carbonate/bicarbonate, and humic acid) on the kinetics and degradation mechanisms of bisphenol A (BPA) during UV-C photolysis and UV/H

Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH

Photodegradation of methylmercury (MeHg) is an important process in mercury cycling that maintains low concentrations of MeHg in freshwater lakes; however, less is known about importance of this process in marine waters. The photo-induced formation of dissolved gaseous mercury (DGM, Hg0) from MeHg removal was investigated. This study examined the effect of various environmental factors (i.e. light wavelength and intensity, and MeHg concentration), and primary water constituents on the abiotic photodegradation of MeHg, especially under different salinity. MeHg photodegradation rates were positively correlated with the UV light intensity, implying that the attenuation of UV radiation had a significant effect on MeHg photodegradation. However, a high dissolved organic matters concentration and salinity inhibited MeHg photodegradation. DGM was always produced during the photodegradation of MeHg. Photodegradation rates of MeHg and DGM production decreased with increasing salinity, suggesting that the p...

The removal and degradation pathways of microcystin-LR (MC-LR, [M+H]

In this study, a horizontal annular inlet was applied to a round-nozzle impactor in an effort to reduce the cut-off diameter. The collection efficiencies of round-nozzle impactors with either a vertical inlet, which has conventionally been used, or a horizontal annular inlet were investigated both numerically and experimentally. For the comparison, the nozzle width, nozzle-to-plate distance, impaction plate diameter, and flow rate of the aerosol drawn into the impactor were set the same for both the vertical inlet impactor and horizontal annular inlet impactor. A parametric study was performed to analyze the effects of the width of the horizontal annular inlet and nozzle throat length on the collection efficiency of round-nozzle impactors with nozzle Reynolds numbers ranging from 500 to 2600. By replacing the vertical inlet with the horizontal annular inlet, the square root of the Stokes number corresponding to the cut-off diameter could be reduced by approximately 30%. In other words, the value of (Stk 50 ) 1/2 was decreased from 0.49 to 0.32 or 0.33 when considering the effect of gravity.

Several predictive factors associated with adverse pregnancy outcomes in female renal recipients have been suggested. Our study aimed to determine the most important factor for prediction of adverse pregnancy outcomes in female renal recipients. We studied 41 pregnancies in 29 female renal recipients retrospectively. We reviewed pregnancy outcomes and possible predictive factors including pre-pregnancy serum creatinine (SCr), pre-pregnancy glomerular filtration rate (GFR), pre-pregnancy hypertension, pre-pregnancy proteinuria, transplantation-pregnancy interval and type of immunosuppressants. We defined an adverse pregnancy-related outcomes index (APOI) that included the following conditions: (i) preeclampsia; (ii) fetal growth restriction (FGR); (iii) prematurity before 34 wk of gestation; (iv) fetal loss (v) graft dysfunction during pregnancy or within three months from delivery. The cutoff of pre-pregnancy serum creatinine and GFR was determined by receiver operating characteristics curves for the prediction of each adverse outcome and APOI. Only pre-pregnancy serum creatinine was associated with adverse pregnancy outcome, and 1 mg/dL was determined to be a useful cutoff for the prediction of each adverse outcomes. Pre-pregnancy SCr ≥ 1 mg/dL was associated with 7.7 times increased risk of preeclampsia and 6.9 times increased risk of APOI. Pre-pregnancy serum creatinine is the most powerful predictive factor for adverse pregnancy outcomes, and

In this study, to examine the accumulated micropollutants in the spent carbon filter used in the water purifier, first, the method to desorb micropollutant from the activated carbon was developed and optimized. Then, using this optimized desorption conditions, we examined which micropollutants exist in spent carbon filters collected from houses in different regions in Korea where water purifiers were used. A total of 11 micropollutants (caffeine (CFF), acetaminophen (ACT), sulfamethazine (SMA), sulfamethoxazole (SMZ), metoprolol (MTP), carbamazepine (CBM), naproxen (NPX), bisphenol-A (BPA), ibuprofen (IBU), diclofenac (DCF), and triclocarban (TCB)) were analyzed using LC/MS-MS from the spent carbon filters. CFF, NPX, and DCF had the highest detection frequencies (>60%) in the carbon filters (n = 100), whereas SMA, SMZ, and MTP were only detected in the carbon filters, but not in the tap waters (n = 25), indicating that these micropollutants, which exist less than the detection limit in tap water, were accumulated in the carbon filters. The regional micropollutant detection patterns in the carbon filters showed higher levels of micropollutants, especially NPX, BPA, IBU, and DCF, in carbon filters collected in the Han River and Nakdong River basins where large cities exist. The levels of micropollutants in the carbon filter were generally lower in the regions where advanced oxidation processes (AOPs) were employed at nearby water treatment plants (WTPs), indicating that AOP process in WTP is quite effective in removing micropollutant. Our results suggest that desorption of micropollutant from the carbon filter used can be a tool to identify micropollutants present in tap water with trace amounts or below the detection limit.