Influence of sediment organic matter origin on the effectiveness of in-situ activated carbon amendment for heavy metal stabilization.

In-situ activated carbon (AC) amendment can be used to chemically stabilize both hydrophobic organic compounds and heavy metals (HMs) in co-contaminated sediment. Although previous findings have highlighted the influence of sediment organic matter (SeOM) on the adsorption of HMs by AC, the specific role of SeOM in HM stabilization remains unclear. In the present study, we investigated how the characteristics of SeOM extracted from field-collected sediment samples taken from two sites affected the adsorption behavior of Zn, Cd, and Pb in AC-amended systems.

Development of an Aptamer-Based qPCR Method for the Selective and Rapid Picomolar-Level Detection of Perfluorooctanesulfonic Acid in Water.

Per- and polyfluoroalkyl substances (PFAS) are widely recognized as emerging contaminants because they are ubiquitous in various environmental media. Their potential for chronic toxicity after prolonged human exposure is a growing concern. Consequently, there is an urgent need to develop an appropriate technology to efficiently treat and rapidly and consistently monitor PFAS levels.

Sequential redox strategies for enhanced defluorination and degradation of a Trifluoromethylated Pharmaceutical using a single bimetallic catalyst.

In this study, we explored for the first time the degradation of trifluoromethylated pharmaceutical through catalytic reduction, oxidation, sequential reduction and oxidation, and sequential oxidation and reduction processes, employing a single bimetallic catalyst which can activate both H and peroxymonosulfate for reduction and oxidation reactions, respectively. Sitagliptin contains both trifluorophenyl and trifluoromethyl moieties, exhibiting different reactivities. While the trifluorophenyl moiety underwent successful defluorination through both reduction and oxidation processes, the trifluoromethyl moiety remained intact and persisted in the majority of transformation products (TPs) as confirmed by high-resolution mass spectrometry, resulting in limited defluorination up to 50 %.

Direct solid-phase nitrogenous fertilizer recovery from wastewater: The hybrid system of membrane contactor and solvent-driven fractional crystallization.

We propose a novel configuration that integrates a membrane contactor with solvent-driven fractional crystallization (SDFC) to recover ammonia from wastewater and produce it as solid-phase nitrogenous fertilizers. A liquid-gas membrane contactor strips ammonia from wastewater in a gaseous form, which enters a strip tank containing a binary mixture of an aqueous anion solution and an organic solvent. There, the ammonia reacts with anions, instantly protonating and forming solid-phase fertilizers.

Ionic liquid-grafted activated carbon for selective removal of PFAS by adsorption in drinking water.

Hydrophobic interaction and anion exchange are major adsorption mechanisms of per- and poly-fluoroalkyl substances (PFAS) for most adsorbents. Activated carbon (AC) primarily adsorbs PFAS through hydrophobic interactions, but its removal efficiency decreases in drinking water treatment plants (DWTP) due to competition from other water constituents. To address this challenge, we grafted hydrophobic ionic liquids (ILs) onto AC, producing hydrophobic adsorbents with PFAS-selective anion exchange sites.

Perfluoroalkyl functionalized-Au nanoparticle sensor: Employing rate of spectrum shifting for highly selective and sensitive detection of per- and polyfluoroalkyl substances (PFASs) in aqueous environments.

Per- and polyfluoroalkyl substances (PFASs) are emerging contaminants detected ubiquitously and have negative impacts on human health and ecosystem; thus, developing sensing technique is important to ensure safety. Herein, we report a novel colorimetric-based sensor with perfluoroalkyl receptor attached to citrate coated gold nanoparticles (Citrate-Au NPs) that can detect several PFASs including perfluorocarboxylates with different chain lengths (PFHxA, PFOA, PFNA, PFDA), perfluorooctanoic sulfonate (PFOS), and perfluorooctanoic phosphonate (PFOPA). The sensor detects PFASs utilizing fluorous interaction between PFASs and the perfluoroalkyl receptor of Citrate-Au NPs in a solution at a fixed salt concentration, inducing changes in nanoparticle dispersity and the solution color.

Influence of chemical structures on reduction rates and defluorination of fluoroarenes during catalytic reduction using a rhodium-based catalyst.

Continuous growth in fluoroarene production has led to environmental pollution and health concerns owing to their persistence, which is attributed to the stable C-F bond in their structures. Herein, we investigated fluoroarene decomposition via hydrodefluorination using a rhodium-based catalyst, focusing on the effects of the chemical structure and functional group on the defluorination yield. Most compounds, except (pentafluoroethyl)benzene, exhibited full or partial reduction with pseudo-first-order rate constants in the range of 0.

Development of ionic-liquid-impregnated activated carbon for sorptive removal of PFAS in drinking water treatment.

Adsorption of per- and poly-fluoroalkyl substances (PFAS) on activated carbon (AC) is considerably hindered by the surface water constituents, degrading the ability of the AC adsorption process to remove PFAS in drinking water treatment. Herein, we developed ionic-liquid-impregnated AC (IL/AC) as an alternative to AC for PFAS sorption and demonstrated its performance with real surface water for the first time. Ionic liquids (ILs) of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL(C2)) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL(C6)) were selected from among 272 different ILs using the conductor-like screening model for realistic solvents (COSMO-RS) simulation.

Predicting apparent adsorption capacity of sediment-amended activated carbon for hydrophobic organic contaminants using machine learning.

In-situ stabilization of hydrophobic organic compounds (HOCs) using activated carbon (AC) is a promising sediment remediation approach. However, predicting HOC adsorption capacity of sediment-amended AC remains a challenge because a prediction model is currently unavailable. Thus, the objective of this study was to develop machine learning models that could predict the apparent adsorption capacity of sediment-amended AC (K) for HOCs.

Reductive degradation mechanism of perfluorooctanoic acid (PFOA) during vacuum ultraviolet (VUV) reactions combining with sulfite and iodide.

In this study, PFOA removal and defluorination were examined during vacuum ultraviolet (VUV) photolysis in the presence of sulfite and sulfite/iodide conditions. PFOA (24 μM) degradation rate constant (k) and defluorination amount in VUV photolysis, and VUV/sulfite, and VUV/sulfite/iodide reactions under nitrogen-purging condition were 5.50 × 10, 7.

Laser-cum-KOH activation allows interfacial engineering of cardboard-derived carbon, tunable ionic states, and universal dye adsorption.

In this study, we demonstrate the preparation of laser-cum KOH-activated porous carbon with tunable ionic states, unique surface chemistry, and physical texture from renewable and environmentally friendly precursors (waste cardboard boxes). The adsorption performance of the engineered adsorbents is examined on the adsorption of methyl blue (MB, anionic) and methylene blue (MeB, cationic). The adsorption mechanism was determined using detailed batch adsorption, and the MB was adsorbed via the formation of ternary complexes, whereas the MeB was adsorbed through cation-π interaction.

Environmental forensic approach towards unraveling contamination sources with receptor models: A case study in Nakdong River, South Korea.

The upstream of Nakdong River is contaminated by heavy metals such as Cd, Cu, Zn, As, and Pb. Although the origin of the contamination is unequivocal, it is suspected that the heavy metals have been leached from several mine tailings and a refinery. Here, receptor models, absolute principal component score (APCS) and positive matrix factorization (PMF), were used to identify the contamination sources.

Thermal treatment of petroleum-contaminated marine sediment according to oxygen availability and temperature: Product quality as a potential plant-growth medium.

The sustainable management of dredged sediment from contaminated sites needs to consider the end-use of the treated sediment. In this regard, modifying conventional sediment treatment techniques to generate a product that is suitable for a range of terrestrial uses is necessary. In the present study, we evaluated the product quality of treated sediment as a potential plant-growth medium following the thermal treatment of marine sediment contaminated by petroleum.

Depth of double-lumen endobronchial tube: a comparison between real practice and clinical recommendations using height-based formulae.

Background: The depth of double-lumen endobronchial tube (DLT) is reportedly known tobe directly proportional to height and several height-based recommendations have beensuggested. This retrospective study was designed to find out the difference between calculated depths using height-based formulae and realistic depths in clinical practice of DLTplacement by analyzing pooled data from patients intubated with left-sided DLT.

Methods: The electronic medical records of adults, intubated with DLT from February 2018to December 2020, were reviewed.

Novel ssDNA aptamer-based fluorescence sensor for perfluorooctanoic acid detection in water.

Per- and polyfluoroalkyl substances (PFAS) are widely detected environmental contaminants, and there is a great need for development of sensor technologies for rapid and continuous monitoring of PFAS. In this study, we have developed fluorescence based aptasensor that can possibly monitor perfluorooctanoic acid (PFOA) in water with limit of detection (LOD) of 0.17 μM.

Heavy metal adsorption capacity of powdered Chlorella vulgaris biosorbent: effect of chemical modification and growth media.

This study investigates the effect of chemical modification and growth medium on the surface characteristics and heavy metal adsorption capacities of Chlorella vulgaris biosorbents, which are prepared in a powder form for the ease of their transport and application. NaOH treatment partially lyses surface cells on cell aggregates, producing rough microscale structures on the biosorbent surface, which enhances the specific surface area by 19-fold and the heavy metal adsorption capacity by factors of 2.4-4.

Exploring reductive degradation of fluorinated pharmaceuticals using AlO-supported Pt-group metallic catalysts: Catalytic reactivity, reaction pathways, and toxicity assessment.

Recently, an increasing number of pharmaceutical compounds has become fluorinated. Owing to their pharmacological efficacy, the use of these fluorinated pharmaceuticals continues to grow, and they constitute 20% of the drugs on the current market. However, only a few studies have investigated the fate and transformation of these emerging contaminants in natural and engineered aquatic environments.

Applying steel slag leachate as a reagent substantially enhances pH reduction efficiency for humidification treatment.

A cost-effective, easy-to-implement, and sustainable approach is needed to mitigate the production of alkaline leachate from steel slags that are reused or disposed in the environment. To address this issue, a humidification treatment process, which is operated by wetting a stack of steel slag using aqueous reagents and letting atmospheric CO to be passively diffused into the slag pores to induce slag carbonation reaction, was previously developed. In this study, we demonstrate that the leachate of raw steel slag can be recycled and used as a humidification reagent to substantially enhance the treatment efficiency as well as to enable operating the process with neither synthetic chemical consumption nor wastewater discharge.

Unraveling the mystery of ultrafine bubbles: Establishment of thermodynamic equilibrium for sub-micron bubbles and its implications.

Hypothesis: We test the validity of the Young-Laplace equation and Henry's law for sub-micron bubble suspensions, which has long been a questionable issue. Application of the two theories allows characterization of bubble diameter and gas molecule partitioning between gaseous and dissolved phases using two easily measurable variables: total gas content (C) and bubble volume concentration (BVC).

Experiments: We measure C and BVC for sub-micron bubble suspensions generated from three pure gases, which allows calculation of bubble diameter for each suspension using the Young-Laplace equation and Henry's law.

Reduction of steel slag leachate pH via humidification using water and aqueous reagents.

A slag humidification process that aims to reduce the leachate pH of steel slag via carbonation was accomplished by simply wetting the slag and exposing it to the atmosphere for passive diffusion of atmospheric CO. The optimization parameters of the process were studied. Results showed that by wetting the slag using various aqueous solutions (deionized water, NaCl solution and NaOH solution), such that its moisture content nearly reaches its water holding capacity, a significant reduction in leachate pH could be achieved.

Effect of basic oxygen furnace slag addition on enhanced alkaline sludge fermentation and simultaneous phosphate removal.

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) from slag. The reactor pH could be adjusted to a target value by the choice of the BOF slag dose.

Effect of using powdered biochar and surfactant on desorption and biodegradability of phenanthrene sorbed to biochar.

The present study aimed to investigate the relationship between the desorption and biodegradability of phenanthrene sorbed to biochars by employing two approaches that may change the desorption and biodegradability: the use of powdered biochars and nonionic surfactants. Biochars derived from two feedstocks (rice husk and sewage sludge; pyrolyzed at 500 °C but showing different aromaticity) were used. When the biochars were powdered to obtain particles <250 μm the mass fractions of the desorbed phenanthrene at ∼80 days (f) increased from 0.

Prediction of long-term heavy metal leaching from dredged marine sediment applied inland as a construction material.

Column leaching studies have been suggested as a reference for site-specific prediction of the long-term leaching characteristics of trace constituents in granular materials used as construction materials. In this study, the concept of the long-term leaching prediction using column studies is applied for dredged marine sediment impacted by heavy metals. The column studies show tailing of the liquid to solid ratio-dependent heavy metal leaching for sediment after heavy metal treatment by acid washing.