New Insights into the Mechanism of the Catalytic Decomposition of Hydrogen Peroxide by Activated Carbon: Implications for Degradation of Diethyl Phthalate

This study investigated the catalytic decomposition of H₂O₂ by activated carbon (AC) and its implications for degradation of diethyl phthalate (DEP). It was found that AC exhibited excellent catalytic ability for decomposition H₂O₂ and degradation of DEP. HNO₃ modification altered the surface characteristics of AC together with the concentrations and types of AC free radicals (FRs), which further promoted generation of ^•OH. Positive correlations were found between FR concentration and generation of ^•OH (<i>R</i>² = 0.856) and between the proportion of surface-bound hydroxyl groups (C–OH) and the decomposition rate of H₂O₂ (<i>R</i>² = 0.776), indicating that FRs in AC were the main contributor to ^•OH generation, whereas C–OH groups were predominantly responsible for decomposition of H₂O₂. Electron capturing studies demonstrated that the decomposition reaction likely involves the transfer of FR electrons to H₂O₂ to induce formation of ^•OH

Thermodynamic Mechanism and Interfacial Structure of Kaolinite Intercalation and Surface Modification by Alkane Surfactants with Neutral and Ionic Head Groups

Intercalation and surface modification of clays with surfactants are the essential process to tailor the clays’ surface chemistry for their extended applications. A full understanding of the interaction mechanism of surfactants with clay surfaces is crucial to engineer clay surfaces for meeting a particular requirement of industrial applications. In this study, the thermodynamic mechanism involved in the intercalation and surface modification of methanol preintercalated kaolinite by three representative alkane surfactants with different head groups, dodecylamine, cetyl­trimethyl­ammonium chloride (CTAC), and sodium stearate, were investigated using the adaptive biasing force accelerated molecular dynamics simulations. In addition, the interaction energies of surfactants with an interlayer environment (alumina surface, siloxane surface, and interlayer methanol) of methanol preintercalated kaolinite were also calculated. It was found that the intercalation free energy of CTAC with a cationic head group was relatively larger than that of stearate with an anionic head group and dodecylamine with a neutral head group. The attractive electrostatic and van der Waals interactions of surfactants with an interlayer environment contributed to the intercalation and surface modification process with the electrostatic force playing the significant role. This study revealed the underlying mechanism involved in the intercalation and surface modification process of methanol preintercalated kaolinite by surfactants, which can help in further design of kaolinite-based organic clays with desired properties for specific applications

Reduction of Carbadox Mediated by Reaction of Mn(III) with Oxalic Acid

Manganese­(III) geocomponents are commonly found in the soil environment, yet their roles in many biogeochemical processes remain unknown. In this study, we demonstrated that Mn^III generated from the reaction of MnO₂ and oxalic acid caused rapid and extensive decompositions of a quinoxaline-di-<i>N</i>-oxide antibiotics, viz carbadox. The reaction occurred primarily at the quinoxaline-di-<i>N</i>-oxide moiety resulting in the removal of one O from N1-oxide and formation of desoxycarbadox. The reaction rate was accelerated by increasing amounts of Mn^III, carbadox and oxalate. The critical step in the overall reaction was the formation of a quinoxaline-di-<i>N</i>-oxide/Mn^III/oxalate ternary complex in which Mn^III functioned as the central complexing cation and electron conduit in which the arrangement of ligands facilitated electron transfer from oxalate to carbadox. In the complex, the CC bond in oxalate was cleaved to create CO₂^–• radicals, followed by electron transfer to carbadox through the Mn^III center. This proposed reaction mechanism is supported by the reaction products formed, reaction kinetics, and quantum mechanical calculations. The results obtained from this study suggest that naturally occurring Mn^III–oxalic acid complexes could reductively decompose certain organic compounds in the environment such as the antibiotic quinoxaline-di-<i>N</i>-oxide

A Mechanistic Understanding of Hydrogen Peroxide Decomposition by Vanadium Minerals for Diethyl Phthalate Degradation

The interaction of naturally occurring minerals with H₂O₂ affects the remediation efficiency of polluted sites in in situ chemical oxidation (ISCO) treatments. However, interactions between vanadium­(V) minerals and H₂O₂ have rarely been explored. In this study, H₂O₂ decomposition by various vanadium-containing minerals including V­(III), V­(IV), and V­(V) oxides was examined, and the mechanism of hydroxyl radical (^•OH) generation for contaminant degradation was studied. Vanadium minerals were found to catalyze H₂O₂ decomposition efficiently to produce ^•OH for diethyl phthalate (DEP) degradation in both aqueous solutions with a wide pH range and in soil slurry. Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) analyses, and free radical quenching studies suggested that ^•OH was produced via single electron transfer from V­(III)/V­(IV) to H₂O₂ followed a Fenton-like pathway on the surface of V₂O₃ and VO₂ particles, whereas the oxygen vacancy (OV) was mainly responsible for ^•OH formation on the surface of V₂O₅ particles. This study provides new insight into the mechanism of interactions between vanadium minerals and H₂O₂ during H₂O₂-based ISCO

Key Role of Persistent Free Radicals in Hydrogen Peroxide Activation by Biochar: Implications to Organic Contaminant Degradation

We investigated the activation of hydrogen peroxide (H₂O₂) by biochars (produced from pine needles, wheat, and maize straw) for 2-chlorobiphenyl (2-CB) degradation in the present study. It was found that H₂O₂ can be effectively activated by biochar, which produces hydroxyl radical (^•OH) to degrade 2-CB. Furthermore, the activation mechanism was elucidated by electron paramagnetic resonance (EPR) and salicylic acid (SA) trapping techniques. The results showed that biochar contains persistent free radicals (PFRs), typically ∼10¹⁸ unpaired spins/gram. Higher trapped [^•OH] concentrations were observed with larger decreases in PFRs concentration, when H₂O₂ was added to biochar, indicating that PFRs were the main contributor to the formation of ^•OH. This hypothesis was supported by the linear correlations between PFRs concentration and trapped [^•OH], as well as <i>k</i>_obs of 2-CB degradation. The correlation coefficients (<i>R</i>²) were 0.723 and 0.668 for PFRs concentration vs trapped [^•OH], and PFRs concentration vs <i>k</i>_obs, respectively, when all biochars pyrolyzed at different temperatures were included. For the same biochar washed by different organic solvents (methanol, hexane, dichloromethane, and toluene), the correlation coefficients markedly increased to 0.818–0.907. Single-electron transfer from PFRs to H₂O₂ was a possible mechanism for H₂O₂ activation by biochars, which was supported by free radical quenching studies. The findings of this study provide a new pathway for biochar implication and insight into the mechanism of H₂O₂ activation by carbonaceous materials (e.g., activated carbon and graphite)

Reductive Hexachloroethane Degradation by S₂O₈^•– with Thermal Activation of Persulfate under Anaerobic Conditions

Despite that persulfate radical (S₂O₈^•–) is an important radical species formed from the persulfate (PS) activation process, its reactivity toward contaminant degradation has rarely been explored. In this study, we found that S₂O₈^•– efficiently degrades the contaminant hexachloroethane (HCA) under anaerobic conditions, whereas HCA degradation is negligible in the presence of oxygen. We observed dechlorination products such as pentachloroethane, tetrachloroethylene, and Cl^– during HCA degradation, which suggest that HCA degradation is mainly a reductive process under anaerobic conditions. Using free radical quenching and electron paramagnetic resonance (EPR) experiments, we confirmed that S₂O₈^•– forms from the reaction between sulfate radical (SO₄^•–) and S₂O₈^2–, which are the dominant reactive species in HCA degradation. Density functional theory (DFT) calculations were used to elucidate the pathways of HCA degradation and S₂O₈^•– radical decomposition. Further investigation showed that S₂O₈^•– can efficiently degrade HCA and DDTs in soil via reduction during the thermal activation of PS under anaerobic conditions. The finding of this study provide a novel strategy for the reductive degradation of contaminant when PS-based in situ chemical oxidation used in the remediation of soil and groundwater, particularly those contaminated with highly halogenated compounds

Degradation of Organic Dyes via Bismuth Silver Oxide Initiated Direct Oxidation Coupled with Sodium Bismuthate Based Visible Light Photocatalysis

Organic dye degradation was achieved via direct oxidation by bismuth silver oxide coupled with visible light photocatalysis by sodium bismuthate. Crystal violet dye decomposition by each reagent proceeded via two distinct pathways, each involving different active oxygen species. A comparison of each treatment method alone and in combination demonstrated that using the combined methods in sequence achieved a higher degree of degradation, and especially mineralization, than that obtained using either method alone. In the combined process direct oxidation acts as a pretreatment to rapidly bleach the dye solution which substantially facilitates subsequent visible light photocatalytic processes. The integrated sequential direct oxidation and visible light photocatalysis are complementary manifesting <i>a</i> > 100% increase in TOC removal, compared to either isolated method. The combined process is proposed as a novel and effective technology based on one primary material, sodium bismuthate, for treating wastewaters contaminated by high concentrations of organic dyes

Table_3_From tumor mutational burden to characteristic targets analysis: Identifying the predictive biomarkers and natural product interventions in cancer management.DOCX

High-throughput next-generation sequencing (NGS) provides insights into genome-wide mutations and can be used to identify biomarkers for the prediction of immune and targeted responses. A deeper understanding of the molecular biological significance of genetic variation and effective interventions is required and ultimately needs to be associated with clinical benefits. We conducted a retrospective observational study of patients in two cancer cohorts who underwent NGS in a “real-world” setting. The association between differences in tumor mutational burden (TMB) and clinical presentation was evaluated. We aimed to identify several key mutation targets and describe their biological characteristics and potential clinical value. A pan-cancer dataset was downloaded as a verification set for further analysis and summary. Natural product screening for the targeted intervention of key markers was also achieved. The majority of tumor patients were younger adult males with advanced cancer. The gene identified with the highest mutation rate was TP53, followed by PIK3CA, EGFR, and LRP1B. The association of TMB (0–103.7 muts/Mb) with various clinical subgroups was determined. More frequent mutations, such as in LRP1B, as well as higher levels of ferritin and neuron-specific enolase, led to higher TMB levels. Further analysis of the key targets, LRP1B and APC, was performed, and mutations in LRP1B led to better immune benefits compared to APC. APC, one of the most frequently mutated genes in gastrointestinal tumors, was further investigated, and the potential interventions by cochinchinone B and rottlerin were clarified. In summary, based on the analysis of the characteristics of gene mutations in the “real world,” we obtained the potential association indicators of TMB, found the key signatures LRP1B and APC, and further described their biological significance and potential interventions.</p

Image_2_From tumor mutational burden to characteristic targets analysis: Identifying the predictive biomarkers and natural product interventions in cancer management.JPEG

High-throughput next-generation sequencing (NGS) provides insights into genome-wide mutations and can be used to identify biomarkers for the prediction of immune and targeted responses. A deeper understanding of the molecular biological significance of genetic variation and effective interventions is required and ultimately needs to be associated with clinical benefits. We conducted a retrospective observational study of patients in two cancer cohorts who underwent NGS in a “real-world” setting. The association between differences in tumor mutational burden (TMB) and clinical presentation was evaluated. We aimed to identify several key mutation targets and describe their biological characteristics and potential clinical value. A pan-cancer dataset was downloaded as a verification set for further analysis and summary. Natural product screening for the targeted intervention of key markers was also achieved. The majority of tumor patients were younger adult males with advanced cancer. The gene identified with the highest mutation rate was TP53, followed by PIK3CA, EGFR, and LRP1B. The association of TMB (0–103.7 muts/Mb) with various clinical subgroups was determined. More frequent mutations, such as in LRP1B, as well as higher levels of ferritin and neuron-specific enolase, led to higher TMB levels. Further analysis of the key targets, LRP1B and APC, was performed, and mutations in LRP1B led to better immune benefits compared to APC. APC, one of the most frequently mutated genes in gastrointestinal tumors, was further investigated, and the potential interventions by cochinchinone B and rottlerin were clarified. In summary, based on the analysis of the characteristics of gene mutations in the “real world,” we obtained the potential association indicators of TMB, found the key signatures LRP1B and APC, and further described their biological significance and potential interventions.</p

Table_7_From tumor mutational burden to characteristic targets analysis: Identifying the predictive biomarkers and natural product interventions in cancer management.DOCX

High-throughput next-generation sequencing (NGS) provides insights into genome-wide mutations and can be used to identify biomarkers for the prediction of immune and targeted responses. A deeper understanding of the molecular biological significance of genetic variation and effective interventions is required and ultimately needs to be associated with clinical benefits. We conducted a retrospective observational study of patients in two cancer cohorts who underwent NGS in a “real-world” setting. The association between differences in tumor mutational burden (TMB) and clinical presentation was evaluated. We aimed to identify several key mutation targets and describe their biological characteristics and potential clinical value. A pan-cancer dataset was downloaded as a verification set for further analysis and summary. Natural product screening for the targeted intervention of key markers was also achieved. The majority of tumor patients were younger adult males with advanced cancer. The gene identified with the highest mutation rate was TP53, followed by PIK3CA, EGFR, and LRP1B. The association of TMB (0–103.7 muts/Mb) with various clinical subgroups was determined. More frequent mutations, such as in LRP1B, as well as higher levels of ferritin and neuron-specific enolase, led to higher TMB levels. Further analysis of the key targets, LRP1B and APC, was performed, and mutations in LRP1B led to better immune benefits compared to APC. APC, one of the most frequently mutated genes in gastrointestinal tumors, was further investigated, and the potential interventions by cochinchinone B and rottlerin were clarified. In summary, based on the analysis of the characteristics of gene mutations in the “real world,” we obtained the potential association indicators of TMB, found the key signatures LRP1B and APC, and further described their biological significance and potential interventions.</p