Degradation mechanisms and toxicity determination of bisphenol A by FeOx-activated peroxydisulfate under ultraviolet light.

Ultraviolet light (UV)-assisted advanced oxidation processes (AOPs) are commonly used to degrade organic contaminants. However, this reaction system's extensive comprehension of the degradation mechanisms and toxicity assessment remains inadequate. This study focuses on investigating the degradation mechanisms and pathways of bisphenol A (BPA), generation of reactive oxygen species (ROS), and toxicity of degradation intermediates in UV/PDS/ferrous composites (FeOx) systems. The degradation rate of BPA gradually increased from the initial 11.92% to 100% within 120 min. Sulfate radicals (SO4.-), hydroxyl radicals (.OH), superoxide anions (O2.-), and singlet oxygen (1O2) were the primary factors in the photocatalytic degradation of BPA in the UV/PDS/FeOx systems. The main reactions of BPA in this system were deduced to be ß-bond cleavage, hydroxyl substitution reaction, hydrogen bond cleavage, and oxidation reaction. A trend of decreasing toxicity for the degradation intermediates of BPA was observed according to the toxicity investigations. The efficient degradation of BPA in UV/PDS/FeOx systems provided theoretical data for AOPs, which will improve the understanding of organic contaminants by FeOx in natural industry wastewater.

The role of superoxide anion to Cr(VI) reduction by pine biochar.

It has been reported that Cr(VI) can be reduced by biochar because of its redox activity. Considering the anionic form of Cr(VI), we hypothesize that the reduction in aqueous phase is significant. However, the contribution of different reactive oxygen species in the biochar-Cr(VI) reaction system has not been distinguished. Herein, we quantitatively identified Cr(VI) adsorption and reduction in biochar systems. The reduction content of Cr(VI) was 1.5 times higher in untreated conditions than in anaerobic conditions. The disappearance of·O2- under anaerobic conditions illustrated that·O2- may be involved in the reduction of Cr(VI). Quenching of·O2- resulted in a decrease of Cr(VI) reduction by 34%, while 1O2 was negligible, probably due to the stronger electron-donating capacity of·O2-. The degradation of nitrotetrazolium blue chloride (quenching agent of·O2-) confirmed that the reduction process of·O2- mainly occurred in the liquid-phase. Boehm titration and quantification of·O2- further elucidated the significant correlation (P < 0.05) between phenolic groups and the formation of·O2-, which implied that phenolic groups acted as the primary electron donors in generating·O2-. This study highlights the importance of the liquid-phase reduction process in removing Cr(VI), which provides theoretical support for biochar conversion of Cr(VI).

Degradation of triclosan by peroxydisulfate/peroxomonosulfate binary oxidants activation under thermal conditions: Efficiency and mechanism.

Peroxydisulfate (PDS) and peroxymonosulfate (PMS) could be efficiently activated by heat to generate reactive oxygen species (ROS) for the degradation of organic contaminants. However, defects including the inefficiency treatment and pH dependence of monooxidant process are prominent. In this study, synergy of heat and the PDS-PMS binary oxidant was studied for efficient triclosan (TCS) degradation and apply in rubber wastewater. Under different pH values, the degradation of TCS followed pseudo-first-order kinetics, the reaction rate constant (kobs) value of TCS in heat/PDS/PMS system increased from 1.8 to 4.4 fold and 6.8-49.1 fold when compared to heat/PDS system and heat/PMS system, respectively. Hydroxyl radicals (·OH), sulfate radicals (SO4·-) and singlet oxygen (1O2) were the major ROS for the degradation of TCS in heat/PDS/PMS system. In addition, the steady-state concentrations of ·OH/1O2 and SO4·-/·OH/1O2 increased under acidic conditions and alkaline conditions, respectively. It was concluded that the pH regulated the ROS for degradation of TCS in heat/PDS/PMS system significantly. Based on the analysis of degradation byproducts, it was inferred that the dechlorination, hydroxylation and ether bond breaking reactions occurred during the degradation of TCS. Moreover, the biological toxicity of the ten byproducts was lower than that of TCS was determined. Furthermore, the heat/PDS/PMS system is resistant to the influence of water substrates and can effectively improve the water quality of rubber wastewater. This study provides a novel perspective for efficient degradation of TCS independent of pH in the heat/PDS/PMS system and its application of rubber wastewater.

Plasma exchange plus glucocorticoids in the treatment of immune checkpoint inhibitor-induced myocarditis: A case series and review.

Immune checkpoint inhibitors (ICIs), including antiprogrammed cell-death (PD)-1/anti-PD-ligand (PDL-1) monoclonal antibodies, are effective at improving the prognosis of patients with cancer. Among immune-related adverse events, myocarditis associated with anti-PD-1/anti-PD-L1 antibodies is rare but lacks effective treatment and mortality is very high. In this study, the authors extracted data from the previous 8 years from electronic medical records housed in the hospital information system to identify patients hospitalized with myocarditis putatively caused by anti-PD-1/anti-PD-L1 tumor therapy. Clinical data from these patients are reported. Four patients who developed myocarditis after undergoing treatment with anti-PD-1/anti-PD-L1 antibodies for malignant tumors, all of whom responded favorably to therapy consisting of plasma exchange and glucocorticoids for myocarditis, and all patients improved and were discharged from hospital. Plasma exchange plus systemic glucocorticoids may be effective for treating anti-PD-1/anti-PD-L1 antibody-induced myocarditis in patients with cancer.

Biochar conductivity and electron donating capability control Cr(VI) bioreduction.

Biochar can facilitate Cr(VI) bioreduction, but it is still undetermined which biochar property control this process. We observed that the apparent Cr(VI) bioreduction by Shewanella oneidensis MR-1 could be identified as a fast and a relatively slow processes. The fast-bioreduction rates (rf0) were 2-15 times higher than the slow-bioreduction rates (rs0). In this study, we investigated the kinetics and efficiency of biochar in promoting Cr(VI) reduction by S. oneidensis MR-1 in the neutral solution using a "dual-process model" (fast and slow processes), and analyzed the mechanisms of biochar concentration, conductivity, particle size and other properties on these two processes. The correlation analysis of these rate constants and biochar properties was carried out. The fast-bioreduction rates were associated with higher conductivity and smaller particle sizes of biochar, which facilitated the direct electron transfer from Shewanella oneidensis MR-1 to Cr(VI). The Cr(VI) slow-bioreduction rates (rs0) were mainly determined by the electron donating capability of biochar and independent of the cell concentration. Our results suggested that Cr(VI) bioreduction was mediated by both electron conductivity and redox potential of biochar. This result is instructive for biochar production. Manipulating biochar properties to control fast and slow Cr(VI) reduction may be helpful to effectively remove or detoxify Cr(VI) in the environment.

Hydrogen Peroxide/Phosphoric Acid Modification of Hydrochars for Sulfamethoxazole and Carbamazepine Adsorption: The Role of Oxygen-Containing Functional Groups.

Emerging pollutants, such as sulfonamide antibiotics and pharmaceuticals, have been widely detected in water and soils, posing serious environmental and human health concerns. Thus, it is urgent and necessary to develop a technology for removing them. In this work, a hydrothermal carbonization method was used to prepare the hydrochars (HCs) by pine sawdust with different temperatures. To improve the physicochemical properties of HCs, phosphoric acid (H3PO4) and hydrogen peroxide (H2O2) were used to modify these HCs, and they were referred to as PHCs and HHCs, respectively. The adsorption of sulfamethoxazole (SMX) and carbamazepine (CBZ) by pristine and modified HCs was investigated systematically. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicated that the H2O2/H3PO4 modification led to the formation of a disordered carbon structure and abundant pores. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy results suggested that carboxyl (-COOH) and hydroxyl (-OH) functional groups of HCs increased after modification, which is the main reason for the higher sorption of SMX and CBZ on H3PO4/H2O2-modified HCs when compared with pristine HCs. In addition, the positive correlation between -COOH/C=O and logKd of these two chemicals also suggested that oxygen-containing functional groups played a crucial role in the sorption of SMX and CBZ. The strong hydrophobic interaction and π-π interaction between CBZ and pristine/modified HCs resulted in its higher adsorption when compared with SMX. The results of this study provide a novel perspective on the investigation of adsorption mechanisms and environmental behaviors for organic contaminants by pristine and modified HCs.

FexO4-enhanced degradation of bisphenol A in visible light/peroxydisulfate system: production of singlet state oxygen.

In this study, ferrous composites (FexO4) were prepared by microreactor to activate peroxydisulfate (PDS) for the degradation of bisphenol A (BPA) with visible (Vis) light irradiation. X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) were used to characterize the morphology and crystal phase of FeXO4. Photoluminescence (PL) spectroscopy combined with amperometric tests were used to determine the role of PDS on the performance of photocatalytic reaction. The main reactive species and intermediates for BPA removal were determined by electron paramagnetic resonance (EPR) measurement and quenching experiments. The result indicated that singlet state oxygen (1O2) contributed more to the BPA degradation than that of other reactive radicals (·OH, SO4·- and ·O2-); these reactive radicals and 1O2 formed by the reaction between photo-generated electrons (e-) and holes (h+) of FexO4 and PDS. During this process, the consumption of e- and h+ also improved their separation efficiency and thus enhanced the degradation of BPA. In addition, the photocatalytic activity of FexO4 in Vis/FexO4/PDS system was 3.2-fold and 6.6-fold higher than that of single FexO4 and PDS under Vis light, respectively. The Fe2+/Fe3+ cycle could effectively drive the photocatalytic activation of PDS through indirect electron transfer and the formation of reactive radicals. This work illustrated that the degradation of BPA was rapidly in Vis/FexO4/PDS system mainly through 1O2, which further improve our understanding on the efficient removal of organic contaminants in the environment.

"Seminal testosterone", rising viewpoint of local spermatogenesis in nonobstructive azoospermia: One center long-term bidirectional cohort study.

Objective: Reproductive hormones are a traditional good method to evaluate spermatogenesis but might not accurately represent local spermatogenesis. To find a more accurate method, seminal reproductive hormones were studied. Methods: A bidirectional cohort study was performed. A total of 126 infertile men from 2018 to 2019 were retrospectively analyzed. They were divided into nonobstructive azoospermia (NOA), oligozoospermia (OLZ) and normal (NOR) groups. A prospective study was conducted on patients in the NOA and OLZ groups for 2 years. Microscopic testicular sperm extraction was performed for NOA patients, who were divided into a focal spermatogenesis group (FS) and an idiopathic azoospermia group (IA). Drug treatment was for OLZ patients, who were divided into a valid group (VA) and an invalid group (IN). The differences in sperm parameters and reproductive hormones were compared. ANOSIM analysis was used between and within groups. Pearson correlation analysis, CO inertia analysis and Proctor's analysis were for relationships. ROC curve for the specificity and sensitivity. Time series analysis was for the trends between hormones and time. Results: The b-FSH, b-LH, s-T and ΔT in the NOA group were significantly higher than those in the OLZ and NOR groups. However, the s-FSH, s-E2, s-P, ΔFSH, ΔLH, ΔP and ΔE2 were lower. Thirty-one NOA patients underwent MTSE, of whom 12 had sperm (FS) and 19 had no sperm (IA). The s-FSH and s-E2 of the FS group were higher than those of the IA group. Twenty-six OLZ patients completed 30 days of treatment, of which 11 had an improved sperm count (VA) and 15 had no (IN). The ΔT of the VA group was higher than that of the IN group. After follow-up for 2 years, 18 patients' results showed that b-FSH, b-LH and s-T were different over time, with delays of 19, 3 and -19 days. SC is closely related to pH, s-FSH, s-LH, s-E2, s-P, s-T, b-FSH, b-LH, ΔFSH, ΔLH, ΔP, ΔE2 and ΔT. There were complex common trends and relationships between different kinds of hormones. s-FSH, s-LH, s-E2, s-P, s-T, b-FSH and b-LH were useful to judge spermatogenesis, of which s-T, b-FSH and b-LH were more sensitive. If s-T, b-FSH and b-LH reached 64.4, 9.4 and 4.7, respectively, their prediction performance was the strongest. Conclusion: Seminal testosterone is sensitive for judging local spermatogenesis in nonobstructive azoospermia patients, which may be the direction of local spermatogenesis in nonobstructive azoospermia. Clinical trial registration: http://www.chictr.org.cn/index.aspx, identifier ChiCTR2200060463.

Prevalence of atrial fibrillation and the risk of cardiovascular mortality among hypertensive elderly population in northeast China.

Little is known about the epidemiology and impact of atrial fibrillation (AF) on cardiovascular diseases (CVD) mortality among hypertensive elderly population in northeast China. The community-based study included 4497 hypertensive elderly residents aged ≥65 years who lived in northeast China from September 2017 to March 2019. Information on CVD deaths was obtained from baseline until July 31, 2021. Cox proportional hazard regression models were performed in the evaluation of CVD mortality. We identified 101 persons with AF. The prevalence of AF was 2.2% among elderly hypertensive population, which increased significantly with age. The prevalence of AF was higher in men than in women. The awareness rate was 51.5%, higher in urban areas than in rural areas (68.8% vs 43.5%, P = .018). Only 4.0% patients received oral anticoagulant (OAC) therapy among AF patients. Moreover, diabetes (26.7%) and dyslipidemia (37.6%) were highly prevalent in AF patients. Furthermore, 212 persons died due to CVD (14.7/1000 person-years) during a median follow-up of 3.2 years. AF patients had a 3.42 (95% CI: 2.07-5.63) times higher risk of CVD mortality than the patients without AF in the fully adjusted model. Therefore, the burden of AF among hypertensive elderly population in northeast China was considerable. Long-term screening and management strategies for AF and related risk factors are required among hypertensive elderly in northeast China.

An inner-filter-effect based ratiometric fluorescent sensor for the detection of uranyl ions in real samples.

In this work, a ratiometric fluorescence system was designed for the detection of trace UO22+ in water based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and gold nanoclusters (AuNCs). IFE-induced fluorescence quenching was achieved due to the enhanced complementary overlap between the absorption spectra of AuNPs and the emission spectrum of AuNCs after the addition of UO22+. Blue carbon dots (B-CDs) were added to serve as reference fluorophores to expand the color tonality and make human eye recognition easier. The ratiometric fluorescent sensor demonstrated a unique fluorescence color change from red to blue when different doses of UO22+ were added, with a detection limit of 8.4 nM. Furthermore, the ratiometric fluorescent sensor was effectively used for UO22+ determination in real-world water samples, with acceptable recoveries.

Functional Biochar and Its Balanced Design.

Biochar has attracted increasing research attention. Various modification methods have been proposed to enhance a certain biochar function. However, these modifications may also result in an unstable structure, additional energy consumption, secondary pollution, and/or extra cost. Balanced consideration of different aspects will ensure the sustainable development of biochar technology. This review first summarizes the most commonly used methods for biochar modification. These methods are categorized according to the purposes of modification, such as surface area enlargement, persistent free radical manipulation, magnetism introduction, and redox potential enhancement. More importantly, a systematic analysis and discussion are provided regarding the balanced consideration of biochar designs, such as the balance between effectiveness and stability, functions and risks, as well as effectiveness and cost. Then, perspectives regarding biochar modification are presented. This review calls for attention that biochar modifications should not be evaluated for their functions only. A balanced design of biochars will ensure both the practicability and the effectiveness of this technology.

Reduction of silver ions to silver nanoparticles by biomass and biochar: Mechanisms and critical factors.

The reduction of metal ions by biomasses (BMs) and biochars (BCs) is often neglected when evaluating the environmental behavior and risk of heavy metals. In this study, the formation mechanisms of silver nanoparticles (AgNPs) when Ag+ coexists with BMs/BCs were investigated. Four types of BMs (pine sawdust, bagasse, lignin, and cellulose) as well as their BCs were investigated for their roles in transforming Ag+ to AgNPs. The electron donating capacity (EDC) of all the BMs/BCs was larger than zero. The UV-Vis spectrometer and scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDX) analysis confirmed the formation of AgNPs. The quantities of AgNPs formed by BM systems were higher than that by their corresponding BCs. The quantities of formed AgNPs by bagasse and its BCs were the highest when compared with other BMs/BCs, which may be due to their highest EDC values. We found that hydroxyl group (-OH) was the important redox-active functional group in BMs and BCs that contributed to Ag+ reduction according to the results from X-ray photoelectron spectrometric (XPS) and Fourier transform infrared spectroscopic (FTIR) analyses. AgNPs formation was enhanced at elevated pH, probably because of the deprotonated functional groups with high EDC values and electron density. The higher temperature could enhance the formation of AgNPs, suggesting that the reduction of Ag+ by BMs/BC was a thermodynamically favored process. This study illustrated that Ag+ was transformed to AgNPs by BMs and BCs through the redox reactive -OH of BMs/BCs, which further improved our understanding on the formation of AgNPs in the environment.

Pyrolyzed carbon derived from red soil as an efficient catalyst for cephalexin removal.

Red soil, a typical soil type in southern China, has been deemed infertile or nutrient-deficient. In this study, red soil was firstly utilized as a substrate for preparing catalysts, which were then successfully applied to the catalytic wet peroxide oxidation (CWPO) of cephalexin. The highest cephalexin removal was 95.23% and TOC removal was 60.58%, with the catalyst pyrolyzed at 500 °C (RC500). The high iron content and proportion of Fe(II) on the surface of RC500 was responsible for the decomposition of H2O2 into· OH. Moreover, the porous structure and existence of other minerals (such as SiO2 and Al2O3) in the catalyst were also significant for enhancing the catalytic activity of RC500. Afterwards, the influencing parameters, including temperature, pH, the dose of H2O2, and catalyst, were examined for cephalexin degradation. It was noteworthy that RC500 was efficient in treating hospital wastewater when using a self-design pilot device. A density functional theory analysis of cephalexin was conducted to establish the possible position attacked by ·OH, and the possibly ruptured one. Meanwhile, the intermediates generated during CWPO were identified. Finally, a reliable degradation pathway of cephalexin was proposed on the basis of the results.

The role of solvents and oxygen-containing functional groups on the adsorption of Bisphenol A on carbon nanotubes.

The wide application of endocrine disruptors (EDs) has recently created great public concerns because of their toxicities. Previous studies have stated that the effect of oxygen-containing functional groups of carbon nanotubes (CNTs) for Bisphenol A (BPA) sorption, but no study has been quantified the exact contribution of the oxygen-containing functional groups. Moreover, the role of solvents on the adsorption of BPA should be considered. Considering the well properties of CNTs, graphitized (MG), carboxylated (MC) and hydroxylated (MH) multi-walled CNTs were selected as model adsorbents, BPA was used as model adsorbate. Solubility and single point adsorption coefficient (logKd) of BPA were n-hexadecane > water > methanol, suggesting that hydrophobic interaction was the main mechanism for BPA sorption on CNTs. For different functional groups of CNTs, π-π interaction between MH and BPA may be stronger than that of MC, and thus the sorption of BPA on MH was higher than that of MC. Moreover, hydrogen bond resulted in the higher adsorption of BPA on MH when compared with MC. The oxygen-containing functional groups of CNTs played a key role for BPA sorption in methanol because the values of contribution were 20%-45% for -OH and were 5%-25% for -COOH. In n-hexadecane, other factors such as hydrophobic interactions should be considered because the contribution percentages of -OH were ca.15% and the values for -COOH were ca.10%. The results are expected to provide important information on the interaction of EDs and CNTs.

Enhanced adsorption of hydrophobic organic contaminants by high surface area porous graphene.

The relatively low surface area and micropore volume of graphene nanosheets (GNS) limit their potential application as effective adsorbents for hydrophobic organic contaminants (HOCs). In this study, KOH etching was used to develop activated GNS (K-GNS) for adsorption of model HOCs such as naphthalene, phenol, nitrobenzene, and bisphenol A. After activation, the specific surface area (SSA) of K-GNS increased to 885 m2/g, which was three times larger than that of GNS. The micropore volume of K-GNS substantially increased and the C/O ratio was doubled. Accordingly, the adsorption capacity of these HOCs on K-GNS was larger than that of pristine GNS (P-GNS) by 2-8 times. The kinetic data was fitted by the pseudo-second-order model, and the adsorption isotherms of HOCs on P-GNS and K-GNS were fitted by the Freundlich model. The desorption studies showed the K-GNS had a lower rate of release than P-GNS. The high adsorption of naphthalene, phenol, nitrobenzene, and bisphenol A on P-GNS and K-GNS is dominated by hydrophobic and π-π interactions. Additionally, the π-π EDA interaction and hydrogen bond between K-GNS and substituents cannot be ignored.

Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores.

Biochars are being increasingly applied in soil for carbon sequestration, fertility improvement, as well as contamination remediation. Phosphoric acid (H3PO4) pretreatment is a method for biochar modification, but the mechanism is not yet fully understood. In this work, biochars and the raw biomass were treated by H3PO4 prior to pyrolysis. Due to an acid catalysis and crosslink, the micropores of the pretreated particles were much more than those without H3PO4 pretreatment, resulting in the dramatical enhancement of specific surface areas of the pretreated particles. Crystalline cellulose (CL) exhibited a greater advantage in the formation of micropores than of amorphous lignin (LG) with H3PO4 modification. The formation mechanisms of micropores were: (a) H+ from H3PO4 contributes to micropores generation via H+ catalysis process; (b) the organic phosphate bridge protected the carbon skeleton from micropore collapse via the crosslinking of phosphate radical. The sorption capacities to carbamazepine (CBZ) and bisphenol A (BPA) increased after H3PO4 modification, which is ascribed to the large hydrophobic surface areas and more abundant micropores. Overall, H3PO4 pretreatment produced biochars with large surface area and high abundance of porous structures. Furthermore, the H3PO4 modified biochars can be applied as high adsorbing material as well as P-rich fertilizer.

Enhanced adsorption of Cu(II) and Cd(II) by phosphoric acid-modified biochars.

In this research, adsorption of Cu(II) and Cd(II) by biochars was investigated. To enhance the adsorption of these two metal ions, a simple modification of biochars by phosphoric acid (H3PO4) was carried out. The surface area was larger and the contents of oxygen-containing functional groups of modified biochars were more than pristine biochars. In comparison with pristine biochar, modified biochars sorbed Cu(II) and Cd(II) much more strongly. Surface area had significant effects on the sorption of Cu(II) and Cd(II) by modified biochars, it also resulted in the higher sorption for the pristine biochar at high pyrolysis temperature. X-ray photoelectron spectroscopy analyses indicated that the quantities of carboxyl (-COOH) and hydroxyl (-OH) functional groups of modified biochars were larger than those of pristine biochar at the same pyrolysis temperature. Compared with that of pristine biochars, the strong ability of -COOH and -OH of modified biochars to form complexes with Cu(II)/Cd(II) ions resulted in higher adsorption of these two metal ions. The phosphorus-containing groups of modified biochars, such as P=O and P=OOH from the result of Fourier transform infrared spectroscopy, interacted and also formed complexes with metal ions, possibly resulting in the enhanced adsorption of Cu(II) and Cd(II). Thus, sorption of metal ions by modified biochars was controlled by the mechanism of surface complexation between oxygen containing functional groups and metals. In general, the H3PO4 modification was an effective method to prepare biochars with a high affinity for the sorption of heavy metals.

Contribution of hydrophobic effect to the sorption of phenanthrene, 9-phenanthrol and 9, 10-phenanthrenequinone on carbon nanotubes.

Polycyclic aromatic hydrocarbons (PAHs), with diverse sources and acute toxicity, are categorized as priority pollutants. Previous studies have stated that the hydrophobic effect controls PAH sorption, but no study has been conducted to quantify the exact contribution of the hydrophobic effect. Considering the well-defined structure of carbon nanotubes and their stable chemical composition in organic solvents, three multi-walled carbon nanotubes (MWCNTs) were selected as a model adsorbent. Phenanthrene (PHE) and its degradation intermediates 9-phenanthrol (PTR) and 9, 10-phenanthrenequinone (PQN) were used as model adsorbates. To quantify the contribution of the hydrophobic effect for these three chemicals, the effect of organic solvent (methanol and hexadecane) was investigated. Adsorption isotherms for PHE, PTR and PQN were well fitted by the Freundlich isotherm model. A positive relationship between adsorption affinities of these three chemicals and specific surface area (SSA) was observed in hexadecane but not in water or methanol. Other factors should be included other than SSA. Adsorption of PQN on MWCNTs with oxygen functional groups was higher than that on pristine MWCNTs due to π-π EDA interactions. The contribution of hydrophobic effect was 50%-85% for PHE, suggesting that hydrophobic effect was the predominant mechanism. This contribution was lower than 30% for PTR/PQN on functionalized MWCNTs. Hydrogen bonds control the adsorption of PTR, and π-π bonding interactions control PQN sorption after screening out the hydrophobic effect in hexadecane. Hydrophobic effect is the control mechanism for nonpolar chemicals, while functional groups of CNTs and solvent types control the adsorption of polar compounds. Extended work on quantifying the relationship between chemical structure and the contribution of the hydrophobic effect will provide a useful technique for PAH fate modeling.

Organic matter source and degradation as revealed by molecular biomarkers in agricultural soils of Yuanyang terrace.

Three soils with different tillage activities were collected and compared for their organic matter sources and degradation. Two soils (TD and TP) with human activities showed more diverse of chemicals in both free lipids and CuO oxidation products than the one (NS) without human activities. Branched alkanoic acids only accounted for less than 5% of lipids, indicating limited microbial inputs in all three investigated soils. The degradation of lignin in NS and TD was relatively higher than TP, probably because of the chemical degradation, most likely UV light-involved photodegradation. Lignin parameters obtained from CuO oxidation products confirmed that woody gymnosperm tissue (such as pine trees) may be the main source for NS, while angiosperm tissues from vascular plant may be the predominant source for the lignins in TD and TP. Analysis of BPCAs illustrated that BC in NS may be mainly originated from soot or other fossil carbon sources, whereas BC in TD and TP may be produced during corn stalk and straw burning. BC was involved in mineral interactions for TD and TP. The dynamics of organic matter needs to be extensively examined for their nonideal interactions with contaminants.

Contribution of coated humic acids calculated through their surface coverage on nano iron oxides for ofloxacin and norfloxacin sorption.

Sorption of organic contaminants on organo-mineral complexes has been investigated extensively, but the sorption contribution of mineral particles was not properly addressed before calculating KOC, especially for ionic organic contaminants. We measured the surface coverage of a humic acid (HA) on nano iron oxides (n-Fe2O3) in a series of synthesized organo-mineral complexes. The contribution of the coated HA to ofloxacin (OFL) and norfloxacin (NOR) sorption in HA-n-Fe2O3 complexes was over 80% of the total sorption with the surface coverage of 36% and fOC of 1.6%. All the coated HA showed higher sorption to NOR and OFL in comparison to the original HA, suggesting HA fractionation and/or physical re-conformation during organo-mineral complex formation. The decreased KOC with multilayer coating may suggest the importance of site-specific interactions for OFL sorption, while the increased KOC with multilayer coating may suggest the importance of partitioning in hydrophobic region for NOR sorption.