Reduction Of Toxicity Research Articles

Sequential DBD plasma-assisted tandem tri-electrodes Fenton process for enhanced antibiotics treatment and denitrification

Ozone generated by dielectric barrier discharge (DBD) plasma has the potential for water treatment; however, its limitations, including water solubility, performance in complex matrices, and resistance to some pollutants. This study explored a sequential DBD plasma assisted by a tandem tri-electrode Fenton (S-PEF) process, using a three-stage treatment approach for degrading antibiotics (sulfamethoxazole, SMX; amoxicillin, AMX; and norfloxacin, NOF) in continuous flow mode for 220-bed volumes. Initially, antibiotics such as SMX and AMX underwent degradation in DBD plasma gas, which housed the mixing chamber. The more resilient NOF was removed by hydroxyl radicals (OH) in the following anodic chamber of the tandem trielectrodes by Fenton assisted oxidation. The continuous cyclic redox regeneration of Fe in tandem trielectrodes prevents secondary Fe sludge pollution. Finally, NO3-N and NO2-N were denitrified into N2 with 95 % selectivity in a cathodic chamber using copper oxide nanowires. This sequential treatment is crucial to mitigating the competitive effects of CO32− and humic acid in wastewater since O3 is less susceptible to them compared to OH. The S-PEF completely degraded all antibiotics regardless of water temperature (10 and 25 °C) compared to sole plasma treatment. Finally, toxicity assessments using an ecological structure–activity relationship (ECOSAR) and E. coli disinfection assays showed a significant reduction in toxicity. This study highlights the promising potential of the S-PEF as an advanced technology for wastewater treatment.

Food processing drives the toxic lectin reduction and bioactive peptide enhancement in Pinellia ternata

Processing can change the properties and flavors of food. Many plants in the Araceae family can be used as food or medicine, but their raw materials are usually toxic, such as Pinellia ternata tuber (PTT). After processing (processed PTT, PPTT), its toxicity is reduced. However, the mechanism remains unclear. In this study, a novel approach integrating liquid chromatography-mass spectrometry, feature-based molecular networking (FBMN), de novo sequencing, and protein database searching was applied to rapidly discover and characterize peptides in PPTT. Potential antihypertensive peptides were screened using in silico methods, angiotensin I-converting enzyme (ACE) inhibitory assay, and molecular docking analysis. A significant decrease was observed in toxic lectins after processing. Meanwhile, a total of 1,954 mass spectral nodes were discovered in PPTT, of which 130 were annotated as peptides by FBMN. These peptides, ranging from 2 to 21 amino acids, were rapidly identified using PEAKS. Notably, 98 peptides were derived from lectins, most of which increased after processing. Approximately 30% of identified peptides were screened for potential high antihypertensive activity in silico. Five peptides exhibited inhibitory effects on ACE, with two showing IC50 values of 131 and 185 μM. Dynamic profiling indicated that 7 to 9 days of processing is optimal for reducing toxicity and enhancing efficacy. More importantly, these peptides were also found in commercial PPTT, confirming their bioactivity contributions. These findings provide insights into the mechanism by which food processing drives the toxic lectin reduction and bioactive peptide enhancement in PTT, providing a novel approach to rapidly discover bioactive peptides, which can be extended to other foods in Araceae family.

Bacterial bioaugmentation for paracetamol removal from water and sewage sludge. Genomic approaches to elucidate biodegradation pathway

Wastewater treatment plants (WWTPs) are recognized as significant contributors of paracetamol (APAP) into the environment due to their limited ability to degrade it. This study used a bioaugmentation strategy with Pseudomonas extremaustralis CSW01 and Stutzerimonas stutzeri CSW02 to achieve APAP biodegradation in solution in wide ranges of temperature (10-40oC) and pH (5-9), reaching DT50 values < 1.5hours to degrade 500mgL-1 APAP. Bacterial strains also mineralized APAP in solution (<30%), but when forming consortia with Mycolicibacterium aubagnense HPB1.1, mineralization significantly increased (up to 74% and 58% for CSW01+HPB1.1 and CSW02+HPB1.1, respectively), decreasing DT50 values to only 1 and 9 days. Despite the complete degradation of APAP and its high mineralization, residual toxicity throughout the process was observed. Three APAP metabolites were identified (4-aminophenol, hydroquinone and trans-2-hexenoic acid) that quickly disappeared, but residual toxicity remained, indicating the presence of other non-detected intermediates. CSW01 and CSW02 degraded also 100% APAP (50mgkg-1) adsorbed on sewage sludge, with DT50 values of only 0.7 and 0.3 days, respectively, but < 15% APAP was mineralized. A genome-based analysis of CSW01 and CSW02 revealed that amidases, deaminases, hydroxylases, and dioxygenases enzymes were involved APAP biodegradation, and a possible metabolic pathway was proposed. Environmental ImplicationThe wide use of paracetamol (APAP) involves ecological risks, being considered an emerging pollutant. APAP excreted by humans ends up in WWTPs, where its elimination is not complete, remaining in part in the effluent treated waters (discharged into surface waters used for soil irrigation) and in part adsorbed on sewage sludge (used as fertilizer in agricultural soils). APAP bioremediation in WWTPs is the unique opportunity to remove it from both matrices before its dispersion in the environment.The novelty of this study is the isolation of two bacterial strains from sewage sludge, P. extremaustralis CSW01 and S. stutzeri CSW02, that could degrade very high concentrations of APAP and their main formed metabolites, both in water and, for the first time, in sewage sludge, in very short periods of time, and even reach high percentages of APAP mineralization in water. Moreover, CSW01 and CSW02 were active under wide ranges of temperature and pH, and are therefore excellent candidates for the chance to achieve a reduction of APAP toxicity in the environment. In addition, by a genome-based analysis, enzymes possibly involved in APAP biodegradation have been identified and a possible degradation pathway has been proposed.

EJS-4 Dose-optimization studies of modern oncology drugs for reduction of toxicity and cost

EJS-4 Dose-optimization studies of modern oncology drugs for reduction of toxicity and cost

Toxicological assessment of reactive blue 19 dye aqueous solutions under UV-LED light

Abstract The dye-contaminated industrial effluent causes serious health issues when it gets mixed with underground water without primary treatment. The current project was designed to treat reactive blue-19 dye aqueous solutions in the presence of hydrogen peroxide (H2O2) and titanium dioxide (TiO2) under UV-LED light. The characterization of the photocatalyst was carried out via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for structure, purity, and surface study. The effect of various factors such as pH, TiO2 dose, UV-LED light exposure time, H2O2, and dye concentration, on the degradation rate and cytotoxicity reduction was evaluated and optimized through the Response Surface Methodology (RSM). The maximum degradation of dye solution and chemical oxygen demand (COD) reduction was achieved at 98.81 and 86.22 %, respectively for 50 ppm solution, using UV-LED/H2O2(3 %)/TiO2(6 g/L) hybrid process. The toxicity evaluation through the Allium cepa test demonstrated a 62.40, 65.2, and 56.97 % increase in root length (RL), root count (RC), and mitotic index (MI), respectively, following treatment with the UV-LED/H₂O₂/TiO₂ combined process for 150 min. The hemolytic and brine shrimp tests revealed a reduction in toxicity up to 92.18 and 84.08 %, respectively, after applying the same treatment. Additionally, the Ames test indicated up to 80.94 % reduction in mutagenicity for TA98 and an 84.04 % reduction for TA100 strain when dye samples were treated with UV-LED light in the presence of H₂O₂ and TiO₂ for 150 min. The findings suggested that UV-LED light in conjunction with H2O2 and TiO2 can be a useful tool for the degradation and detoxification of toxic pollutants found in textile wastewater.

Increased oxygen partial pressure enhances toxicity reduction by membrane aerated biofilm reactor treating oil and gas industrial wastewater

Wastewater produced during oil and gas extraction processes is one of the largest residual water streams. Also known as produced water (PW), it has a complex composition and is typically toxic to aquatic ecosystems. This study explores the use of membrane aerated biofilm reactors (MABR) for biological removal of dissolved organic compounds and associated toxicity. Three different oxygen partial pressures (0.2, 0.6 and 1 bar), the last two mimicking subsea pressures at 20 and 40 m below the sea level, respectively, were tested at three different hydraulic retention times (HRT of 24, 12 and 6 h). Reactors were fed both with onshore and offshore PW. Removal rates for organic carbon increased at decreasing HRT. Highest oxygen partial pressure led to best performance at 6 h HRT (30.1 ± 3.0 g-COD m−2 d−1) when treating onshore PW and at all HRT when treating offshore PW, with highest COD removal rate still at 6 h HRT (9.4 ± 1 g-COD m−2 d−1). Removal efficiencies ranged from 78 % when treating onshore PW at 24 h HRT to 36–49 % when treating offshore PW at 6 h HRT. All treatments led to a reduction in toxicity (>92 % reduction for offshore PW), with 0.2 bar oxygen partial pressure showing worst performance, while 0.6 and 1 bar did not show significant differences. The biofilms were dominated by hydrocarbonoclastic, responsible of hydrocarbons biodegradation, and sulfur cycling bacteria. Overall, MABR were effective treating PW and operating at higher oxygen partial pressures yield to better performance, especially at high volumetric loading rates.

Synthesis of a novel biomass-based flame retardant featuring vinyl-terminated chemical cross-linking and application in flame retardancy, smoke suppression, toxicity reduction and mechanical enhancement of PAN composite fibers

To develop green and efficient polyacrylonitrile (PAN) fibers with excellent fire safety properties, a new biomass-based flame retardant (PPC@VA) with vinyl-terminated groups was prepared based on the reaction of hexachlorocyclotriphosphonitrile, teat polyphenols, ethylenediamine and vinylphosphonic acid. Subsequently, it was mixed with spinning solution to obtain PPC@VA/PAN through wet spinning, which were then chemically cross-linked via thermal initiation to achieve CC-PPC@VA/PAN fibers. CC-PPC@VA/PAN showed a significant improvement in flame retardancy with a limiting oxygen index value of 32.5 %. The peak of smoke production rate, total smoke production and CO production rate were lowered by 81.9 %, 77.8 % and 91.3 %. Besides, the hazardous gas HCN was greatly suppressed. Owing to the macromolecular entanglement, hydrogen bonding and covalent cross-linking, CC-PPC@VA/PAN improved elongation at break and tensile strength by 19.2 % and 72.1 %. Also, chemical cross-linking contributed to decrease the migration of P/N-based flame retardants, lower the potential risk of water eutrophication and increased the service life of the fibers.

Enhanced self-cementation of arsenic-contaminated soil via activation of non-thermal plasma-irradiated ferromanganese: A mechanistic investigation

The self-cementation characteristics of arsenic (As)-contaminated soil were comprehensively investigated in this study. Different non-thermal plasma-irradiated binary (hydro)oxides of polyvalent ferromanganese (poly-Fe-Mn) were synthesized and exploratorily dispersed to soil samples to activate solidification and stabilization during the self-cemented process. The maximum compressive strength of 56.35 MPa and the lowest leaching toxicity of 0.004 mg/L were obtained in the proof test under optimal conditions (i.e., the mass ratio of the poly-Fe-Mn to the soil sample of 0.05; the mass ratio of the composite alkali activator (NaOH + CaO) to the soil sample of 0.25; the mass ratio of CaO to NaOH of 1.5; the mass ratio of the DI water to the binder of 0.515). The composite alkaline activator primarily contributed to the strength formation of the self-cemented matrix while the poly-Fe-Mn significantly influenced the reduction of the As-leaching toxicities. The poly-Fe-Mn maintained diffusion-controlled polycondensation and strengthened the nucleation process during self-cementation. The amount of water and the dosage of poly-Fe-Mn caused an interactive influence on the self-cemented solidification of contaminated soils. The solidified samples with poly-Fe-Mn exhibited better thermal decomposition than their counterparts, reflecting the enhancement of poly-Fe-Mn to the matrix. Some minerals including C-S-H, kaolinite, gehlenite, diopside sodian, augite, and albite were matched in the samples, directly demonstrating the geopolymerization-steered self-cementation of the As soil. The employment of poly-Fe-Mn not only reinforced the immobilization of As pollutants in the matrix but also induced the self-cementation of soils by intensifying the composite alkaline-activated geopolymerization kinetics.

Solar-activated tin oxide photocatalysis for efficient naphthenic acids removal and toxicity reduction in oil sands process water

This research studied, for the first time, the effect of activating tin oxide (SnO2) under simulated solar light for treating real oil sands process water (OSPW). The solar/SnO2 system effectively eliminated fluorophore organic contaminants, classical naphthenic acids (O2-NAs), and oxidized NAs (Oxy-NAs) from OSPW. The best experimental conditions to remove over 90 % of O2-NAs were found to be 0.5 g/L SnO2 under 8 h of irradiation. HO• and O2•– species identified by electron paramagnetic resonance (EPR) analysis played an important role in the degradation of NAs and other contaminants in real OSPW. The initial toxic effects of untreated OSPW were noticeably reduced after treatment, with a reduction of approximately 50 % in acute toxicity using Microtox® bioassay and over 80 % in the level of bioavailable hydrocarbons. In addition, the process also demonstrated a significant reduction in immunotoxicity as measured using an immune cell bioassay and reduced the toxic effects on Staphylococcus warneri using an adapted bacterial minimal inhibitory concentration (MIC) viability assay. These results suggest that treated OSPW by SnO2 under solar light has high environmental compatibility, indicating it is safe for reuse in further applications.

Protective and Therapeutic Effects of Medicinal Plants Against Food Additive-Induced Toxicity.

For thousands of years, people have used medicinal plants and in many parts of the world, traditional medicines continue to play a significant role in the standard treatment of a wide range of illnesses. With changes in modern eating patterns, there has recently been an increase in the use of processed foods. Furthermore, the use of food additives has increased in tandem with the production of processed foods. The dosage levels used for these additives are determined using empirical analyses. However, some additives have demonstrated long-term toxic effects on the human body in toxicity tests. Plants are one of the main sources of biologically active substances and in recent years, many studies have focused on the health benefits of phytochemicals and plant-derived extracts in the treatment and prevention of food additive toxicity. This review clarified studies on several medicinal plants, such as &lt;i&gt;Physalis peruviana&lt;/i&gt; L., &lt;i&gt;Jatropha tanjorensis&lt;/i&gt;, &lt;i&gt;Cymbopogon citratus&lt;/i&gt;,&lt;i&gt; Ficus carica&lt;/i&gt;, &lt;i&gt;Rosmarinus officinalis&lt;/i&gt; L. and others. The findings presented here demonstrate these plants' efficiency and success in preventing and lowering the toxicity of food additives through antioxidant activity reducing oxidative stress, and reduction in renal and hepatic toxicity. Therefore, these plant extracts have a preventive and therapeutic effect in reducing toxicity and may be the best option for reducing the toxicity of food additives in the future. Moreover, additional research is required to confirm the biologically active components found in medicinal plants that are effective in reducing this toxicity.

Anaerobic dynamic membrane bioreactor treating sulfamethoxazole wastewater: advantages of dynamic membrane and its fouling mechanism

Discharge of improperly treated sulfamethoxazole (SMX) wastewater seriously threats environmental security and public health. Anaerobic dynamic membrane bioreactors (AnDMBRs) technology would be cost-effective for SMX wastewater treatment, considering its low cost and satisfactory treatment efficiency. The performance of AnDMBR, though demonstrated to be excellent in treating many types of wastewaters, was for the first time investigated for treating SMX wastewater. Particular efforts were devoted to elucidating the advantages of dynamic membrane (DM) and the governing mechanism responsible for DM fouling with the presence of SMX. The threshold SMX concentration for AnDMBR was found to be 90 mg/L and the AnDMBR exhibited excellent removal efficiency of COD (90.91 %) and SMX (88.95 %) as well as satisfactory acute toxicity reduction rate (88.84 %). It was noteworthy that the DM made indispensable contributions to the removal of COD (14.26 %) and SMX (22.20 %) as well as the acute reduction of toxicity (25.81 %). The presence of SMX significantly accelerated DM fouling mainly by increasing its specific resistance, which was attributed to the increased content of small particles, high-valence metal ions and EPS content (mainly hydrophobic proteins), resulting in a denser DM structure with lower porosity. Besides, the biofouling-related bacteria (Firmicutes) was found to be enriched in the DM with the presence of SMX.

Health risk assessment of metal contamination in Malaysian rice (Oryza sativa): The impact of parboiling on toxic metal reduction prior to cooking

SummaryMetal contamination in rice grains is a critical global issue, posing serious health risks and affecting food safety, especially in countries like Malaysia where rice is a staple food. This study aimed to assess the effectiveness of various cooking treatments, with a focus on parboiling before absorption cooking (PBA), in reducing metal contamination in Malaysian rice. Metal levels were measured using tandem inductively coupled plasma mass spectrometry (ICP‐MS/MS), and health risks were assessed following USEPA guidelines. Parboiling before absorption cooking was found to eliminate 77.9% of toxic metals and 68.4% of essential metals while keeping arsenic (As), cadmium (Cd) and lead (Pb) concentrations below permissible limits. Deterministic health risk assessment indicated that PBA reduced hazard index by 84.5% and lifetime carcinogenic risk (LCR) from As exposure by 88.9%. Hazard quotient for nickel (Ni) and zinc (Zn) remained acceptable for all age groups except for As in children, where LCR exceeded permissible limits. Monte Carlo simulations revealed that over 95% of individuals across age groups faced unacceptable non‐carcinogenic and carcinogenic risks from As exposure, regardless of cooking method. In conclusion, PBA effectively lowered metal concentrations and health risks, especially for toxic metals in rice. Future studies could enhance risk assessment accuracy by analysing metal bioavailability and speciation of metals particularly As.

Crude oil degrading efficiency of formulated consortium of bacterial strains isolated from petroleum-contaminated sludge.

Crude oil contamination has been widely recognized as a major environmental issue due to its various adverse effects. The use of inhabitant microorganisms (native to the contaminated sites) to detoxify/remove pollutants owing to their diverse metabolic capabilities is an evolving method for the removal/degradation of petroleum industry contaminants. The present study deals with the exploitation of native resident bacteria from crude oil contaminated site (oil exploration field) for bioremediation procedures. Fifteen (out of forty-four) bioremediation-relevant aerobic bacterial strains, belonging to the genera of Bacillus, Stenotrophomonas, Pseudomonas, Paenibacillus, Rhizobium, Burkholderia, and Franconibacter, isolated from crude oil containing sludge, have been selected for the present bioremediation study. Crude oil bioremediation performance of the selected bacterial consortium was assessed using microcosm-based studies. Stimulation of the microbial consortium with nitrogen or phosphorous led to the degradation of 60-70% of total petroleum hydrocarbon (TPH) in 0.25% and 0.5% crude oil experimental sets. CO2 evolution, indicative of crude oil mineralization, was evident with the highest evolution being 28.6mgmL-1. Ecotoxicity of treated crude oil-containing media was assessed using plant seed germination assay, in which most of the 0.25% and 0.5% treated crude oil sets gave positive results thereby suggesting a reduction in crude oil toxicity.

In vivo Imaging and Pharmacokinetics of Percutaneously Injected Ultrasound and X-ray Imageable Thermosensitive Hydrogel loaded with Doxorubicin versus Free Drug in Swine.

Intratumoral injections often lack visibility, leading to unpredictable outcomes such as incomplete tumor coverage, off-target drug delivery and systemic toxicities. This study investigated an ultrasound (US) and x-ray imageable thermosensitive hydrogel based on poloxamer 407 (POL) percutaneously delivered in a healthy swine model. The primary objective was to assess the 2D and 3D distribution of the hydrogel within tissue across three different needle devices and injection sites: liver, kidney, and intercostal muscle region. Secondly, pharmacokinetics of POL loaded with doxorubicin (POLDOX) were evaluated and compared to free doxorubicin injection (DOXSoln) with a Single End Hole Needle. Utilizing 2D and 3D morphometrics from US and x-ray imaging techniques such as Computed Tomography (CT) and Cone Beam CT (CBCT), we monitored the localization and leakage of POLDOX over time. Relative iodine concentrations measured with CBCT following incorporation of an iodinated contrast agent in POL indicated potential drug diffusion and advection transport. Furthermore, US imaging revealed temporal changes, suggesting variations in acoustic intensity, heterogeneity, and echotextures. Notably, 3D reconstruction of the distribution of POL and POLDOX from 2D ultrasound frames was achieved and morphometric data obtained. Pharmacokinetic analysis revealed lower systemic exposure of the drug in various organs with POLDOX formulation compared to DOXSoln formulation. This was demonstrated by a lower area under the curve (852.1 ± 409.1 ng/mL·h vs 2283.4 ± 377.2 ng/mL·h) in the plasma profile, suggesting a potential reduction in systemic toxicity. Overall, the use of POL formulation offers a promising strategy for precise and localized drug delivery, that may minimize adverse effects. Dual modality POL imaging enabled analysis of patterns of gel distribution and morphology, alongside of pharmacokinetics of local delivery. Incorporating hydrogels into drug delivery systems holds significant promise for improving the predictability of the delivered drug and enhancing spatial conformability. These advancements can potentially enhance the safety and precision of anticancer therapy.

P19-38 In vitro assessment of tobacco free nicotine pouches reveals marked reductions in toxicity when compared to cigarettes

P19-38 In vitro assessment of tobacco free nicotine pouches reveals marked reductions in toxicity when compared to cigarettes

A new strategy for constructing ZIF-67@PBA core-shell 3D cross-heterostructures for improving fire safety of TPU at ultra-low addition amount

Thermoplastic polyurethane (TPU) has an extensive application in many different industries. However, serious fire hazards and smoke toxicity have been the main reason limiting its wide application. Therefore, it is necessary and urgent to perform flame retardant and smoke suppression treatment for TPU. In recent years, metal-organic framework compounds (MOFs) have very promising application prospects in the fields of flame-retardant polymer composites. However, there is a problem of low flame-retardant efficiency for the original MOFs alone in polymer composites. It is reported the multi-level and multi-structured flame-retardant system has better flame-retardant efficiency than the traditional structures. So, the dual MOF core-shell heterostructure may have more effective heat reduction and smoke suppression than any single component. In this paper, a core-shell 3D cross-heterostructures nanohybrid (ZIF-67H@PBA) was prepared using ZIF-67H as the host MOF and Prussian blue nanocubes (PBA) as the guest MOF. It has been found that TPU/ZIF-67H@PBA composites with ultra-low additions have excellent fire safety. Compared with those of pure TPU, the peak heat release rate (PHRR), total smoke release (TSP), and smoke factor (SF) of the samples with 0.5wt% ZIF-67H@PBA were reduced by 33.6 %, 47 %, and 61 %, respectively. At the same time, a cone calorimeter (CCT), a homemade soot sampling device and a gas chromatography-mass spectrometry (GC–MS) coupling with each other were constructed and used to demonstrate the most realistic effects of flame retardants in terms of smoke suppression and toxicity reduction. This work provides a new strategy to design TPU flame retardants.

Facilely tuning the triazine-heptazine ratios in crystalline g-C3N4 for efficient photo-degradation of tylosin

Intrinsically, g-C3N4 has high-density defects, insufficient efficiencies of photogenerated charge carrier separation and transfer, and inadequate photocatalytic ability against antibiotics. A facile crystallinity engineering on g-C3N4 assisted by molten-salts and simultaneously fine-tuning the triazine-heptazine ratio led to forming type-II homojunctions, without introducing foreign atoms and being metal-free. It was successfully achieved through modulating the calcination temperatures and using KCl-LiCl. The salts accelerated deamination reaction kinetics, tuned the unit ratio, and improved the degree of carbon nitride polymerization. At a triazine-heptazine ratio of 74:26 obtained at 450 °C, 10 mg/L of tylosin was completely mitigated within 9 min by the catalyst. Active radicals including O2− and OH were boosted from charge carriers under visible light, and the recombination of photogenerated excitons was relieved on the interfaces of the homojunctions. Breaking glycosidic bonds and dropping off deoxyglycosyl moieties are considered the main degradation mechanism. The cytotoxicity and acute toxicity of the degradation product are classified as harmless. In addition, 3D-molecular docking between the transformation products and target proteins (L4 and L22) in ribosome confirms toxicity reduction. This work paves a way for efficient and harmless photocatalytic degradation of tylosin by facilely modulating the unit ratio and enhancing the crystallinity of carbon nitride without introducing foreign atoms.

Efficient co-removal of aqueous Cr(VI) and ciprofloxacin by alkali lignin-derived carbon supported nanoscale zero-valent iron via adsorption and redox synergistic mechanisms

Developing an efficient co-removal strategy is crucial for the treatment of combined contaminants with heavy metals and antibiotics due to their great threat to sustainable advancement and ecological preservation. Herein, the efficient co-removal of aqueous hexavalent chromium (Cr(VI)) and ciprofloxacin (CIP) is achieved via a newly developed composite of nanoscale zero-valent iron particles embedded into alkali lignin-derived carbon (nZVI/ALC) without external assistance (such as light, advanced oxidants). nZVl/ALC demonstrates superior co-removal efficiencies of Cr(VI) (99.9 %) and CIP (89.9 %) with high removal kinetic rate constants of 1.595 and 0.779 min−1, respectively. The underlying mechanisms involving the co-removal of Cr(VI) and CIP verify that Cr(VI) ions are adsorbed onto the skeleton of nZVI/ALC originating from the electrostatic interaction, and CIP molecules adsorbed on nZVl/ALC act as a bridge, complexing with the Cr(VI) ions to promote Cr(VI) removal. Meanwhile, the CIP adsorption by nZVI/ALC involves hydrogen bonding, π-π interaction, and complexation. The coexisting Cr(VI) ions are transformed into Cr(III) components with abundant electron transfer, leading to the generation of more •O2– radicals, thus the self-generating reactive oxygen species (•OH, •O2– and 1O2) in ambient-air condition promote CIP degradation in the binary system. The CIP molecules’ degradation pathways mainly include piperazine ring cracking, piperazine epoxidation, quinolone ring opening and defluorination according to the analysis of HPLC-MS and FuKui function, along with the gradual reduction in toxicity throughout the degradation process of CIP molecules. This study offers a new insight on the co-removal of Cr(VI) and CIP, which would provide promising guidance for the remediation of compound wastewater with heavy metals and antibiotics.

Mechanistic investigation of azo dye removal from carbon-deficient dyeing wastewater using horizontal-vertical constructed wetlands

Azo dye degradation can be achieved by simulating a series of anaerobic and aerobic conditions within the constructed wetland (CW) system. The current investigation evaluated the effectiveness of a baffled horizontal-vertical CW system, planted with Typha angustifolia, simulating anaerobic-aerobic conditions to treat carbon-deficient synthetic dyeing wastewater containing 100 mg/L Reactive Yellow 145 (RY145) azo dye. In the absence of an available carbon source in dyeing wastewater, an optimum quantity of sodium acetate was supplemented as the substrate for microbial degradation of RY145. Influent dyeing wastewater characteristics were 5555 ADMI colour, 461 mg/L chemical oxygen demand (COD) and 39 mg/L total nitrogen (TN). During the operation period, the CW system achieved 97% colour, 87% COD, 95% ammonium nitrogen (NH4+-N) and 71% TN removals at 4 d hydraulic retention time (HRT). Favourable environmental conditions, such as low redox conditions and substrate availability in horizontal CW, contributed to a significant reduction in colour (96%). Most TN reduction (67%) happened in horizontal CW by denitrification and plant assimilation. The metagenomic study revealed that Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes were responsible for pollutant degradation within horizontal CW. The UV–visible spectra and high-resolution liquid chromatograph mass spectrometer (HR-LCMS) analysis confirmed that dye degradation intermediates generated from the breakage of azo bonds were eliminated in vertical CW with high redox conditions. The results of the phytotoxicity and fish toxicity experiments demonstrated a substantial toxicity reduction in the CW system-treated effluent.

Potency Evaluations of Recombinant Botulinum Neurotoxin A1 Mutants Designed to Reduce Toxicity.

Recombinant mutant holotoxin BoNTs (rBoNTs) are being evaluated as possible vaccines against botulism. Previously, several rBoNTs containing 2-3 amino acid mutations in the light chain (LC) showed significant decreases in toxicity (2.5-million-fold-12.5-million-fold) versus wild-type BoNT/A1, leading to their current exclusion from the Federal Select Agent list. In this study, we added four additional mutations in the receptor-binding domain, translocation domain, and enzymatic cleft to further decrease toxicity, creating 7M rBoNT/A1. Due to poor expression in E. coli, 7M rBoNT/A1 was produced in an endogenous C. botulinum expression system. This protein had higher residual toxicity (LD50: 280 ng/mouse) than previously reported for the catalytically inactive rBoNT/A1 containing only three of the mutations (>10 µg/mouse). To investigate this discrepancy, several additional rBoNT/A1 constructs containing individual sets of amino acid substitutions from 7M rBoNT/A1 and related mutations were also endogenously produced. Similarly to endogenously produced 7M rBoNT/A1, all of the endogenously produced mutants had ~100-1000-fold greater toxicity than what was reported for their original heterologous host counterparts. A combination of mutations in multiple functional domains resulted in a greater but not multiplicative reduction in toxicity. This report demonstrates the impact of production systems on residual toxicity of genetically inactivated rBoNTs.