Response of petroleum-contaminated soil to chemical oxidation combined with biostimulation.

In this study, a microcosm experiment was conducted to investigate the effects of Na2S2O8 preoxidation combined with biostimulation on petroleum-contaminated soil remediation. The response of microbial community during this process was explored using BIOLOG ECO microplate carbon utilization method and 16 s rDNA high-throughput sequencing. The results showed that use of 10 mg/g Na2S2O8 removed 19.8 % of the petroleum hydrocarbons, reduced soil biotoxicity and did not affect soil microbial activity compared to other concentrations. Therefore, sodium persulfate of ca. 10 mg/g was used to oxidize petroleum in soil before the biostimulation experiment with organic and inorganic fertilizers. Our finding showed that the content of total petroleum hydrocarbons (TPHs) in soil was reduced by 43.3 % in inorganic fertilizer treatment after 60 days. The results of BIOLOG ECO microplate carbon utilization analysis and 16 S rDNA high-throughput sequencing further confirmed that biostimulation quickly restored the microbial activities in oxidant treated soil. The main marker bacteria in chemical oxidation combined with biostimulation remediation were Arthrobacter and Paenarthrobacter, and their relative abundances were both significantly negatively correlated with the content of petroleum hydrocarbons in soil.

Low-temperature Slow-release Permanganate Gel for Groundwater Remediation: Dynamics in Saturated Porous Media.

Due to its adverse health and environmental impacts, groundwater contamination by toxic organic compounds such as chlorinated solvents is a global concern. The slow-release permanganate gel (SRP-G) is a mixture of potassium permanganate (KMnO4) and colloidal silica solution. The SRP-G is designed to radially spread after injection via wells, gelate in situ to form gel barriers containing permanganate (MnO4-), and slowly release MnO4- to treat plumes of chlorinated solvents in groundwater. This study aimed to characterize the effects of temperature on the dynamics of SRP-G in saturated porous media. In gelation batch tests, the viscosity of ambient-temperature (24 oC) SRP-G with 30 g/L-KMnO4 was 21 cP at 70 min, 134 cP at 176 min, and peaked at 946 cP to solidification at 229 min. The viscosity of low-temperature (4 oC) SRP-G with 30 g/L-KMnO4 was 71 cP at 273 min, 402 cP at 392 min, and peaked at 818 cP to solidification at 485 min. A similar pattern, e.g., increased gelation lag time with low-temperature SRP-G, was observed for SRP-Gs with 40 g/L, 50 g/L, and 60 g/L KMnO4. In flow-through tests using a glass column filled with saturated sands, injection rates, spreading rates, and release durations were 0.6 mL/min, 46 mm/min, and 33 hr for KMnO4(aq), 0.2 mL/min, 2 mm/min, and 38 hr for ambient-temperature SRP-G, and 0.4 mL/min, 16 mm/min, and 115 hr for low-temperature SRP-G, respectively. These results indicated that the injectability, injection rate, and gelation lag time of SRP-G and the size, release rate, and release duration of MnO4- gel barriers can be increased at low temperatures. The low-temperature SRP-G scheme can be useful for treating large or dilute dissolved plumes of chlorinated solvents or other pollutants in groundwater.

Low-disturbance land remediation using vertical groundwater circulation well technology: The first commercial deployment in an operational chemical plant.

Soil and groundwater contamination by organic pollutants from chemical plants presents significant risks to both environmental and human health. We report a significant field trial where a chemical plant in operation showed soil and groundwater pollution, as verified by sampling and laboratory tests. While many remediation methods are effective, they often require the temporary shutdown of plant operations to install necessary equipment. This paper introduces a novel combination of low-disturbance contaminant remediation technologies, including groundwater circulation well (GCW), pump and treat (P&T), and in-situ chemical oxidation (ISCO) technologies, that can be applied on the premises of an active plant without halting production. The groundwater with dissolved contaminants is removed through P&T and GCW, while GCW enhances ISCO that focus on eliminating the remaining hard-to-pump contaminants. Results show: (1) after two years of remediation effort, the contaminant levels in soil and groundwater were significantly reduced; (2) the average concentration reduction rate of four contaminants, including 1,2-dichloroethane, methylbenzene, ethylbenzene, and M&P-xylene, exceeds 98 %; (3) the presented remediation strategy results in the improvement of remediation efficiency. Specifically, the concentration of 1,2-dichloroethane in observation wells dropped from 40,550.7 µg/L to 44.6 µg/L. This study offers a first-of-its-kind commercial deployment of a GCW-based remediation strategy in an active plant setting. Moreover, the combined remediation approach presented here can serve as a model for designing contaminant remediation projects that require minimal operational disruption.

Direct Electron Transfer-Driven Nontoxic Oligomeric Deposition of Sulfonamide Antibiotics onto Carbon Materials for In Situ Water Remediation.

The rising in situ chemical oxidation (ISCO) technologies based on polymerization reactions have advanced the removal of emerging contaminants in the aquatic environment. However, despite their promise, uncertainties persist regarding their effectiveness in eliminating structurally complex contaminants, such as sulfonamide antibiotics (SAs). This study elucidated that oligomerization, rather than mineralization, predominantly governs the removal of SAs in the carbon materials/periodate system. The amine groups in SAs played a crucial role in forming organic radicals and subsequent coupling reactions due to their high f- index and low bond orders. Moreover, the study highlighted the robust adhesion of oligomers to the catalyst surface, facilitated by enhanced van der Waals forces and hydrophobic interactions. Importantly, plant and animal toxicity assessments confirmed the nontoxic nature of oligomers deposited on the carbon material surface, affirming the efficacy of carbon material-based ISCO in treating contaminated surface water and groundwater. Additionally, a novel classification approach, Δlog k, was proposed to differentiate SAs based on their kinetic control steps, providing deeper insights into the quantitative structure-activity relationship (QSAR) and facilitating the selection of optimal descriptors during the oligomerization processes. Overall, these insights significantly enhance our understanding of SAs removal via oligomerization and demonstrate the superiority of C-ISCO based on polymerization in water decontamination.

Understanding the dynamics of enhanced light non-aqueous phase liquids (LNAPL) remediation at a polluted site: Insights from hydrogeophysical findings and chemical evidence.

This study intricately unfolds a pioneering methodology for remediating contaminants in a persistent light non-aqueous phase liquids (LNAPL)-contaminated site. The remediation strategy seamlessly integrates enhanced desorption and in-situ chemical oxidation (ISCO), orchestrating the injection of PetroCleanze® (a desorbent) and RegenOx® (an oxidizer) through meticulously designed wells. These injections, based on detailed geological and hydrogeological assessments, aim at mobilizing residual contaminants for subsequent extraction. Real-time subsurface dynamics are investigated through geophysical monitoring, employing electrical resistivity tomography (ERT) to trace reagent migration pathways via their effect on bulk electrical conductivity. The integration of groundwater sampling data aims at providing additional insights into the transformations of contaminants in the spatiotemporal context. Vivid two-dimensional time-lapse ERT sections showcase the evolution of resistivity anomalies, providing high-resolution evidence of the heterogeneity, dispersion pathways of desorbent and oxidant, and residual LNAPL mobilization. Hydrochemical analyses complement this, revealing effective mobilization processes with increasing aqueous concentrations of total petroleum hydrocarbons (TPH) over time. Speciation analysis unveils the intricate interplay of desorption and oxidation, portraying the dynamic fractionation of hydrocarbon components. The hydrogeophysical and data-driven framework not only delivers qualitative and quantitative insights into reagent and contaminant distribution but also enhances understanding of spatial and temporal physio-chemical changes during the remediation process. Time-lapse ERT visually narrates the reagent's journey through time, while chemical analyses depict the unfolding processes of desorption and oxidation across space and time. The coupling of hydrogeophysical and chemical findings pictures the transformations of pollutants following the sequence of product injection and the push and pull activities, capturing the removal of mobilized contaminants through hydraulic barrier wells. This enhanced understanding proves instrumental towards optimizing and tailoring remediation efforts, especially in heterogeneous environmental settings. This study establishes a new standard for a sophisticated and innovative contaminant remediation approach, advancing environmental practices through the harmonized analysis of geophysical and chemical data.

Oxidation of chromium(â ¢): A potential risk of using chemical oxidation processes for the remediation of 2-chlorophenol contaminated soils.

Chemical oxidation processes are widely used for the remediation of organically contaminated soils, but their potential impact on variable-valence and toxic metals such as chromium (Cr) is often overlooked. In this study, we investigated the risk of Cr(Ⅲ) oxidation in soils during the remediation of 2-chlorophenol (2-CP) contaminated soils using four different processes: Potassium permanganate (KMnO4), Modified Fenton (Fe2+/H2O2), Alkali-activated persulfate (S2O82-/OH-), and Fe2+-activated persulfate (S2O82-/Fe2+). Our results indicated that the KMnO4, Fe2+/H2O2, and S2O82-/Fe2+ processes progressively oxidized Cr(III) to Cr(Ⅵ) during the 2-CP degradation. The KMnO4 process likely involved direct electron transfer, while the Fe2+/H2O2 and S2O82-/Fe2+ processes primarily relied on HO• and/or SO4•- for the Cr(III) oxidation. Notably, after 4 h of 2-CP degradation, the Cr(VI) content in the KMnO4 process surpassed China's 3.0 mg kg-1 risk screening threshold for Class I construction sites, and further exceeded the 5.7 mg kg-1 limit for Class II construction sites after 8 h. Conversely, the S2O82-/OH- process exhibited negligible oxidation of Cr(III), maintaining a low oxidation ratio of 0.13%, as highly alkaline conditions induced Cr(III) precipitation, reducing its exposure to free radicals. Cr(III) oxidation ratio was directly proportional to oxidant dosage, whereas the Fe2+/H2O2 process showed a different trend, influenced by the concentration of reductants. This study provides insights into the selection and optimization of chemical oxidation processes for soil remediation, emphasizing the imperative for thorough risk evaluation of Cr(III) oxidation before their application.

Sequential oxidation-composting-phytoremediation treatment for the management of an oily sludge from petroleum refinery.

Oily sludges are generated in large quantities in petroleum refinery wastewater treatment plants. Given their complex composition, they are classified as hazardous waste. Selecting a single treatment technique for their remediation is challenging. This work aims to assess the extent of composting followed by phytoremediation on an oily sludge from an API separator unit, pre-treated by chemical oxidation with alkaline activated persulfate (PS). 18% of total petroleum hydrocarbons (TPH) were determined by IR spectroscopy. The aliphatic hydrocarbon content was 4714 ± 250 ppm by GC-FID, and aromatics were not detectable, suggesting a high amount of non-chromatographable complex hydrocarbons. The density of generalist and hydrocarbon-degrading populations of the oily sludge estimated by quantitative polymerase chain reaction (qPCR) evidenced an autochthonous microbiota with hydrocarbon-degrading capacity. The oxidative treatment with PS removed 31% of the TPH determined by IR after 20 days. The significant reduction of the native bacterial community was counterbalanced by coupling a composting treatment. Co-composting the sludge with goat manure and oat straw produced, after a year, a 96% reduction in TPH content, regardless of the oxidative pretreatment. Organic matter transformation was evidenced by the decrease of dissolved organic carbon (DOC) and the variation in E4/E6 ratio. The matrices obtained of composting were used as substrates for phytoremediation for 4 months. Ryegrass seeds were planted in both PS-treated and untreated sludge substrates. The presence of the plant grown in the pre-oxidised and composted substrate resulted in a higher aerial biomass of ryegrass (67%), an increase in enzymatic activities, and higher concentration of DOC, although without evidence of additional dissipation of TPH. The dynamics of the bacterial communities of the different substrates generated during the biological treatment were analyzed by Illumina NovaSeq DNA sequencing of 16S rRNA amplicons. The findings mirrored a succession compatible with that described in contaminated matrices, but also in other non-contaminated ones. According to these findings, an organic matter transformation process occurred, which included the complex hydrocarbons of the oily sludge, resulting in an active substrate that promoted the retention of nutrients and water and provided the necessary support for plant development.

Enhanced phenanthrene biodegradation in river sediments by harnessing calcium peroxide nanoparticles and minerals in Sphingomonas sp. DSM 7526 cultivation.

Coupling chemical oxidation and biodegradation to remediate polycyclic aromatic hydrocarbon (PAH)-contaminated sediment has recently gained significant attention. In this study, calcium peroxide nanoparticles (nCaO2) were utilized as an innovative oxygen-releasing compound for in-situ chemical oxidation. The study investigates the bioremediation of phenanthrene (PHE)-contaminated sediment inoculated with Sphingomonas sp. DSM 7526 bacteria and treated with either aeration or nCaO2. Using three different culture media, the biodegradation efficiencies of PHE-contaminated anoxic sediment, aerobic sediment, and sediment treated with 0.2% w/w nCaO2 ranged from 57.45% to 63.52%, 69.87% to 71.00%, and 92.80% to 94.67%, respectively. These values were significantly higher compared to those observed in non-inoculated sediments. Additionally, the type of culture medium had a prominent effect on the amount of PHE removal. The presence of minerals in the culture medium increased the percentage of PHE removal compared to distilled water by about 2-10%. On the other hand, although the application of CaO2 nanoparticles negatively impacted the abundance of sediment bacteria, resulting in a 30-42% decrease in colony-forming units after 30 days of treatment, the highest PHE removal was obtained when coupling biodegradation and chemical oxidation. These findings demonstrate the successful application of bioaugmentation and chemical oxidation processes for treating PAH-contaminated sediment.

Comparison of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) removal in a combined adsorption and electrochemical oxidation process.

This study focused on three of the most studied PFAS molecules, namely perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS). They were compared in terms of their adsorption capacity onto graphite intercalated compound (GIC), a low surface area, highly conductive and cheap adsorbent. The adsorption on GIC followed a pseudo second order kinetics and the maximum adsorption capacity using Langmuir was 53.9 µg/g for PFOS, 22.3 µg/g for PFOA and 0.985 µg/g for PFBS due to electrostatic attraction and hydrophobic interactions. GIC was added into an electrochemical oxidation reactor and >100 µg/L PFOS was found to be fully degraded (<10 ng/L) leaving degradation by-products such as PFHpS, PFHxS, PFPeS, PFBS, PFOA, PFHxA and PFBA below 100 ng/L after 5 cycles of adsorption onto GIC for 20 min followed by regeneration at 28 mA/cm2 for 10 min. PFBS was completely removed due to degradation by aqueous electrons on GIC flakes. Up to 98 % PFOA was removed by the process after 3 cycles of adsorption onto GIC for 20 min followed by regeneration at 25 mA/cm2 for 10 min. When PFBS was spiked individually, only 17 % was removed due to poor adsorption on GIC. There was a drop of 3-40 % by treating PFOS, PFOA and smaller sulfonates in a real water matrix under the same electrochemical conditions (20 mA/cm2), but PFOS and PFOA removal percentage were 95 and 68 % after 20 min at 20 mA/cm2.

Effect of successive recycling and reuse of acid liquor for the synthesis of graphene oxides with higher oxygen-to-carbon ratios.

Graphene has recently drawn exponential attention due to its surprising physicochemical properties and diversified field of applications. Although graphene oxides (GOs), itself is an exclusive material, it is also an intermediate product for the production of reduced graphene oxides (rGOs), graphene and their derivatives, which are other more superficial materials. In this study, GOs with higher oxygen to carbon ratios were synthesized following the Tour method, where the excess feed acid liquor (FAL) of mixed concentrated sulfuric and orthophosphoric acids at a ratio of 90:10 was recovered from the reaction slurries by applying the centrifugation technique. About 80-90 % of the FAL was recycled and reused as feed for the subsequent batches. The changes in the properties of FAL for the five consecutive recycling and reuse were studied. The properties of recycled FALs were investigated by measuring density, moisture content, pH, and ion concentration. The consecutive recycling of FALs tends to increase the moisture content about 0.5% in each recycles. Ion-chromatography (IC) was used to measure the variation in SO42- and PO43- ions in the FALs. The H2SO4 reacts with KMnO4 and crystalized out from the recovered FAL faster than the phosphoric acid. So, sulfuric acid content in the makeover FALs must be greater than primary FAL. The product GOs were characterized using FT-IR, FT-Raman, UVVis, STA, SEM, XPS, Zeta-potential, and particle size analyzers. The variation of the properties of GOs with the changes in the reaction parameters such as temperature and time were investigated and correlated with the product yield. It was observed that the effect of temperature on the reaction rate was found to be negatively and positive with the reaction time. The oxygen-to-carbon atomic ratio from XPS analysis was found 66.7%, which supported the increase in product yields 66.9% in the experimental results. The effect of acid concentration, reaction temperature, and time on the GOs properties were satisfactory, correlated, and easily controllable with the reaction conditions. A higher extent of oxidation and enhanced product yields 65-70% were observed at 60-70 °C and 14-18 h. A mixture of nano- and macro-molecular GOs was obtained, and their compositions were easily controllable and separable by controlling the reaction conditions. A correlation was made among the properties of synthesized GOs, FAL, and recycled FAL and reaction conditions.

Effect of interaction between dissolved organic matter and iron/manganese (hydrogen) oxides on the degradation of organic pollutants by in-situ advanced oxidation techniques.

Iron and manganese (hydrogen) oxides (IMHOs) exhibit excellent redox capabilities for environmental pollutants and are commonly used in situ chemical oxidation (ISCO) technologies for the degradation of organic pollutants. However, the coexisting dissolved organic matter (DOMs) in surface environments would influence the degradation behavior and fate of organic pollutants in IMHOs-based ISCO. This review has summarized the interactions and mechanisms between DOMs and IMHOs, as well as the properties of DOM-IMHOs complexes. Importantly, the promotion or inhibition impact of DOM was discussed from three perspectives. First, the presence of DOMs may hinder the accessibility of active sites on IMHOs, thus reducing their efficiency in degrading organic pollutants. The formation of compounds between DOMs and IMHOs alters their stability and activity in the degradation process. Second, the presence of DOMs may also affect the generation and transport of active species, thereby influencing the oxidative degradation process of organic pollutants. Third, specific components within DOMs also participate and affect the degradation pathways and rates. A comprehensive understanding of the interaction between DOMs and IMHOs helps to better understand and predict the degradation process of organic pollutants mediated by IMHOs in real environmental conditions and contributes to the further development and application of IMHO-mediated ISCO technology.

Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring.

Groundwater contamination is a threat to drinking water resources and ecosystems. Remediation by injection of chemical reagents into the aquifer may be preferred to excavation to reduce cost and environmental footprint. Yet, successful remediation requires complete contact between contamination and reagents. Subsurface heterogeneities are often responsible for diffusion into low-permeable zones, which may inhibit this contact. Monitoring the spatial distribution of injected reagents over time is crucial to achieve complete interaction. Source zone contamination at megasites is particularly challenging to remediate and monitor due to the massive scale and mixture of contaminants. Source zone remediation at Kærgård Plantation megasite (Denmark) is monitored here, with a new methodology, using high-resolution cross-borehole electrical resistivity tomography (XB-ERT) imaging calibrated by chemical analyses on groundwater samples. At this site, high levels of toxic non-aqueous phase liquids (NAPL) are targeted by in-situ chemical oxidation using activated persulfate. It may take numerous injection points with extensive injection campaigns to distribute reagents, which requires an understanding of how reagent may transport within the aquifer. A geophysical (XB-ERT) monitoring network of unprecedented size was installed to identify untreated zones and help manage the remediation strategy. The combination of spatially continuous geophysical information with discrete but precise chemical information, allowed detailed monitoring of sulfate distribution, produced during persulfate activation. Untreated zones identified in the first remediation campaign were resolved in the second campaign. The monitoring allowed adjusting the number of injection screens and the injection strategy from one campaign to the next, which resulted in better persulfate distribution and contaminant degradation in the second campaign. Furthermore, geophysical transects repeated over the timespan of a remediation campaign allowed high-resolution time-lapse imaging of reagent transport, which could in the future improve the predictability of transport models, compared to only using on a-priori assumptions of the hydraulic conductivity field.

Interactions of ferrate(VI) and aquatic humic substances in water treatment.

Aquatic humic substances, encompassing humic acid (HA) and fulvic acid (FA), can influence the treatment of ferrate(VI), an emerging water treatment agent, by scavenging Fe(VI) to accelerate its decomposition and hinder the elimination of target micro-pollutants. Meanwhile, HA and FA degrade the water quality through the transformation to disinfection byproducts over disinfection, contribution to water color, and enhanced mobility of toxic metals. However, the interplay with ferrate(VI) and humic substances is not well understood. This study aims to elucidate the interactions of ferrate(VI) with HA and FA for harnessing ferrate(VI) in water treatment. Laboratory investigations revealed distinctive biphasic kinetic profiles of ferrate(VI) decomposition in the presence of HA or FA, involving a 2nd order kinetic reaction followed by a 1st-order kinetic reaction. Both self-decay and reactions with the humic substances governed the ferrate(VI) decomposition in the initial phase. With increasing dissolved organic carbon (DOC), the contribution of self-decomposition to ferrate(VI) decay declined, while humic substance-induced ferrate(VI) consumption increased. To assess relative contributions of the two factors, DOC50% was first introduced to represent the level at which the two factors equally contribute to the ferrate(VI) loss. Notably, DOC50% (11.90 mg/L for HA and 13.10 mg/L for FA) exceeded typical DOC in raw water, implying that self-decay predominantly governs ferrate(VI) consumption. Meanwhile, ferrate(VI) could degrade and remove HA and FA across different molecular weight (MW) ranges, exhibiting treatment capabilities that are either better or, at least, equivalent to ozone. The ferrate(VI) treatment attacked high MW, hydrophobic organic molecules, accompanied by the production of low MW, more hydrophilic compounds. Particularly, FA was more effectively removed due to its smaller molecular sizes, higher solubility, and lower carbon contents. This study provides valuable insights into the effective utilization of ferrate(VI) in water treatment in presence of humic substances.

Oxidation processes and me.

This publication summarizes my journey in the field of chemical oxidation processes for water treatment over the last 30+ years. Initially, the efficiency of the application of chemical oxidants for micropollutant abatement was assessed by the abatement of the target compounds only. This is controlled by reaction kinetics and therefore, second-order rate constant for these reactions are the pre-requisite to assess the efficiency and feasibility of such processes. Due to the tremendous efforts in this area, we currently have a good experimental data base for second-order rate constants for many chemical oxidants, including radicals. Based on this, predictions can be made for compounds without experimental data with Quantitative Structure Activity Relationships with Hammet/Taft constants or energies of highest occupied molecular orbitals from quantum chemical computations. Chemical oxidation in water treatment has to be economically feasible and therefore, the extent of transformation of micropollutants is often limited and mineralization of target compounds cannot be achieved under realistic conditions. The formation of transformation products from the reactions of the target compounds with chemical oxidants is inherent to oxidation processes and the following questions have evolved over the years: Are the formed transformation products biologically less active than the target compounds? Is there a new toxicity associated with transformation products? Are transformation products more biodegradable than the corresponding target compounds? In addition to the positive effects on water quality related to abatement of micropollutants, chemical oxidants react mainly with water matrix components such as the dissolved organic matter (DOM), bromide and iodide. As a matter of fact, the fraction of oxidants consumed by the DOM is typically > 99%, which makes such processes inherently inefficient. The consequences are loss of oxidation capacity and the formation of organic and inorganic disinfection byproducts also involving bromide and iodide, which can be oxidized to reactive bromine and iodine with their ensuing reactions with DOM. Overall, it has turned out in the last three decades, that chemical oxidation processes are complex to understand and to manage. However, the tremendous research efforts have led to a good understanding of the underlying processes and allow a widespread and optimized application of such processes in water treatment practice such as drinking water, municipal and industrial wastewater and water reuse systems.

Combined adsorption and electrochemical oxidation of perfluorooctanoic acid (PFOA) using graphite intercalated compound.

Perfluorooctanoic acid (PFOA) is a bioaccumulative synthetic chemical containing strong C-F bonds and is one of the most common per- and polyfluoroalkyl substances (PFAS) detected in the environment. Graphite intercalated compound (GIC) flakes were used to adsorb and degrade PFOA through electrochemical oxidation. The adsorption followed the Langmuir model with a loading capacity of 2.6 µg PFOA g-1 GIC and a second-order kinetics (3.354 g µg-1 min-1). 99.4% of PFOA was removed by the process with a half-life of 15 min. When PFOA molecules broke down, they released various by-products, such as short-chain perfluoro carboxylic acids like PFHpA, PFHxA, and PFBA. This breakdown indicates the cleavage of the perfluorocarbon chain and the release of CF2 units, suggesting a transformation or degradation of the original compound into these smaller acids. Shorter-chain perfluorinated compounds had slower degradation rates compared to longer-chain ones. Combining these two methods (adsorption and in situ electrochemical oxidation) was found to be advantageous because adsorption can initially concentrate the PFOA molecules, making it easier for the electrochemical process to target and degrade them. The electrochemical process can potentially break down or transform the PFAS compounds into less harmful substances through oxidation or other reactions.

Towards a better understanding of light-glucose induced modifications on the structure and biological activity of formulated Nivolumab.

In the last years, monoclonal antibodies (mAbs) have rapidly escalated as biopharmaceuticals into cancer treatments, mainly for their target specificity accompanied by less side effects than the traditional chemotherapy, and stimulation of reliable long-term anti-tumoral responses. They are potentially unstable macromolecules under shaking, temperature fluctuations, humidity, and indoor and outdoor light exposure, all stressors occurring throughout their production, transport, storage, handling, and administration steps. The chemical and physical modifications of mAbs can lead not only to the loss of their bioactivity, but also to the enhancement of their immunogenicity with increasing risk of severe hypersensitivity reactions in treated patients because of aggregation. The photostability of Nivolumab, the active principle of Opdivo®, has been here studied. The chemical modifications detected by LC-MS/MS after the light stressor showed Trp and Met mono and double oxidations as primary damage induced by light on this mAb. The oxidations were stronger when the mAb was diluted in sterile glucose solution where 5-HMF, a major heat glucose degradation product, acted as singlet oxygen producer under irradiation. However, no significant changes in the mAb conformation were found. On the contrary, formation of a significant extent of aggregates has been detected after shining high simulated sunlight doses. This again took place particularly when Nivolumab was diluted in sterile glucose, thus raising a direct correlation between the aggregation and the oxidative processes. Finally, the biological activity under light stress assessed by a blockade assay test demonstrated the maintenance of the PD-1 target recognition even under high light doses and in glucose solution, in line with the preservation of the secondary and tertiary structures of the mAb. Based on our results, as sterile glucose is mostly used for children's therapies, special warnings, and precautions for healthcare professionals should be included for their use to the pediatric population.

Contaminant degradation by •OH during sediment oxygenation: Effect of abundant solid matrix in aquifer.

Aquifer oxygenation for hydroxyl radical (•OH) production has been recently proposed as a promising strategy for in-situ remediation. However, the high performance of this process was justified at low solid-to-liquid ratios (SLRs) of suspension systems. It remains unclear whether and how the performance is affected by abundant solid matrixes. Here we assessed the influence of SLR on •OH production and contaminant degradation during sediment oxygenation. Cumulative •OH increased from 21.8 to 165.2 µM when the SLR increased from 200 to 1600 g/L, while phenol degradation increased with the increase in SRL at the values lower than 1200 g/L and decreased at higher SLRs. As the main sediment component, silica exhibited a negligible effect on •OH production and phenol degradation because of the weak adsorption towards aqueous Fe(II). Whereas, the other component, alumina, significantly inhibited •OH production and phenol degradation because it strongly adsorbed Fe(II). •OH scavenging by solid reactive matrixes was mainly responsible for the inhibition at high SLRs. The scavenging effect could be mitigated by mediating the main reactive Fe(II) species from solid-adsorbed to dissolved phase with ligand addition. Our findings are important for understanding the side reactions and optimizing the remediation performance during aquifer oxygenation.

Real-time monitoring of in situ chemical oxidation (ISCO) of dissolved TCE by integrating electrical resistivity tomography and reactive transport modeling.

Successful in situ chemical oxidation (ISCO) applications require real-time monitoring to assess the oxidant delivery and treatment effectiveness, and to support rapid and cost-effective decision making. Existing monitoring methods often suffer from poor spatial coverage given a limited number of boreholes in most field conditions. The ionic nature of oxidants (e.g., permanganate) makes time-lapse electrical resistivity tomography (ERT) a potential monitoring tool for ISCO. However, time-lapse ERT is usually limited to qualitative analysis because it cannot distinguish between the electrical responses of the ionic oxidant and the ionic products from contaminant oxidation. This study proposed a real-time quantitative monitoring approach for ISCO by integrating time-lapse ERT and physics-based reactive transport models (RTM). Moving past common practice, where an electrical-conductivity anomaly in an ERT survey would be roughly linked to concentrations of anything ionic, we used PHT3D as our RTM to distinguish the contributions from the ionic oxidant and the ionic products and to quantify the spatio-temporal evolution of all chemical components. The proposed approach was evaluated through laboratory column experiments for trichloroethene (TCE) remediation. This ISCO experiment was monitored by both time-lapse ERT and downstream sampling. We found that changes in inverted bulk electrical conductivity, unsurprisingly, did not correlate well with the observed permanganate concentrations due to the ionic products. By integrating time-lapse ERT and RTM, the distribution of all chemical components was satisfactorily characterized and quantified. Measured concentration data from limited locations and the non-intrusive ERT data were found to be complementary for ISCO monitoring. The inverted bulk conductivity data were effective in capturing the spatial distribution of ionic species, while the concentration data provided information regarding dissolved TCE. Through incorporating multi-source data, the error of quantifying ISCO efficiency was kept at most 5 %, compared to errors that can reach up to 68 % when relying solely on concentration data.

Straightforward Synthesis of Pentagon-Embedded Expanded [11]Helicenes for Radiative Cooling Property.

Two new pentagon-embedded carbo[11]helicenes have been designed and synthesized in a three-step process, which are the first example of carbo[11]helicenes through the post-functionalization of twistacene. TD-DFT analyses indicate that both of them possess high enantiomerization barriers of 42.29 kcal/mol and 40.76 kcal/mol, respectively. They emit strong red fluorescence and can be chemically oxidized into stable cationic radicals upon addition of AgSbF6 evidenced by the bathochromic-shifted absorption spectra and the appearance of electronic paramagnetic resonance (EPR) signals. In addition, such helical derivatives can be chosen as radiative cooling materials in a glass model house, and the maxima of 5.4 °C for the former and 6.5 °C for the latter are found in the comparative tests, which might be caused by the NIR reflective response.