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Water Research Feb 2024As a widely used feed additives, p-arsanilic acid (p-AsA) frequently detected in the environment poses serious threats to aquatic ecology and water security due to its...
Comparative study of Fe(II)/sulfite, Fe(II)/PDS and Fe(II)/PMS for p-arsanilic acid treatment: Efficient organic arsenic degradation and contrasting total arsenic removal.
As a widely used feed additives, p-arsanilic acid (p-AsA) frequently detected in the environment poses serious threats to aquatic ecology and water security due to its potential in releasing more toxic inorganic arsenic. In this work, the efficiency of Fe(II)/sulfite, Fe(II)/PDS and Fe(II)/PMS systems in p-AsA degradation and simultaneous arsenic removal was comparatively investigated for the first time. Efficient p-AsA abatement was achieved in theses Fe-based systems, while notable discrepancy in total arsenic removal was observed under identical acidic condition. By using chemical probing method, quenching experiments, isotopically labeled water experiments, p-AsA degradation was ascribed to the combined contribution of high-valent Fe(IV) and SOin these Fe(II)-based system. In particular, the relative contribution of Fe(IV) and SO in the Fe(II)/sulfite system was highly dependent on the molar ratio of [Fe(II)] and [sulfite]. Negligible arsenic removal was observed in the Fe(II)/sulfite and Fe(II)/PDS systems, while ∼80% arsenic was removed in the Fe(II)/PMS system under identical acidic condition. This interesting phenomenon was due to that ferric precipitation only occurred in the Fe(II)/PMS system. As(V) was further removed via adsorption onto the iron precipitate or the formation of ferric arsenate-sulfate compounds, which was confirmed by particle diameter measurements, fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Through tuning solution pH, complete removal of total arsenic could achieve in all three systems. Among these three Fe-based technologies, the hybrid oxidation-coagulation Fe(II)/PMS system demonstrated potential superiority for arsenic immobilization by not requiring pH adjustment for coagulation and facilitating the in-situ generation of ferric arsenate-sulfate compounds with comparably low solubility levels like scorodite. These findings would deepen the understanding of these three Fe-based Fenton-like technologies for decontamination in water treatment.
Topics: Arsenic; Arsenates; Arsanilic Acid; Iron; Ferric Compounds; Oxidation-Reduction; Sulfites; Sulfates; Sulfur Oxides; Ferrous Compounds; Water Pollutants, Chemical
PubMed: 38070343
DOI: 10.1016/j.watres.2023.120967 -
Brain Sciences Nov 2019When vestibular function is lost, vestibular compensation works for the reacquisition of body balance. For the study of vestibular dysfunction and vestibular...
When vestibular function is lost, vestibular compensation works for the reacquisition of body balance. For the study of vestibular dysfunction and vestibular compensation, surgical or chemical labyrinthectomy has been performed in various animal species. In the present study, we performed chemical labyrinthectomy using arsanilic acid in mice and investigated the time course of vestibular compensation through behavioral observations and histological studies. The surgical procedures required only paracentesis and storage of 50 µL of -arsanilic acid sodium salt solution in the tympanic cavity for 5 min. From behavioral observations, vestibular functions were worst at 2 days and recovered by 7 days after surgery. Spontaneous nystagmus appeared at 1 day after surgery with arsanilic acid and disappeared by 2 days. Histological studies revealed specific damage to the vestibular endorgans. In the ipsilateral spinal vestibular nucleus, the medial vestibular nucleus, and the contralateral prepositus hypoglossal nucleus, a substantial number of c-Fos-immunoreactive cells appeared by 1 day after surgery with arsanilic acid, with a maximum increase in number by 2 days and complete disappearance by 7 days. Taken together, these findings indicate that chemical labyrinthectomy with arsanilic acid and the subsequent observation of vestibular compensation is a useful strategy for elucidation of the molecular mechanisms underlying vestibular pathophysiologies.
PubMed: 31752103
DOI: 10.3390/brainsci9110329 -
NeuroImage Feb 2021Unilateral damage to the inner ear results in an acute vestibular syndrome, which is compensated within days to weeks due to adaptive cerebral plasticity. This process,...
Unilateral damage to the inner ear results in an acute vestibular syndrome, which is compensated within days to weeks due to adaptive cerebral plasticity. This process, called central vestibular compensation (VC), involves a wide range of functional and structural mechanisms at the cellular and network level. The short-term dynamics of whole-brain functional network recruitment and recalibration during VC has not been depicted in vivo. The purpose of this study was to investigate the interplay of separate and distinct brain regions and in vivo networks in the course of VC by sequential [F]-FDG-PET-based statistical and graph theoretical analysis with the aim of revealing the metabolic connectome before and 1, 3, 7, and 15 days post unilateral labyrinthectomy (UL) in the rat. Temporal changes in metabolic brain connectivity were determined by Pearson's correlation (|r| > 0.5, p < 0.001) of regional cerebral glucose metabolism (rCGM) in 57 segmented brain regions. Metabolic connectivity analysis was compared to univariate voxel-wise statistical analysis of rCGM over time and to behavioral scores of static and dynamic sensorimotor recovery. Univariate statistical analysis revealed an ipsilesional relative rCGM decrease (compared to baseline) and a contralesional rCGM increase in vestibular and limbic networks and an increase in bilateral cerebellar and sensorimotor networks. Quantitative analysis of the metabolic connections showed a maximal increase from baseline to day 3 post UL (interhemispheric: 2-fold, ipsilesional: 3-fold, contralesional: 12-fold) and a gradual decline until day 15 post UL, which paralleled the dynamics of vestibular symptoms. In graph theoretical analysis, an increase in connectivity occurred especially within brain regions associated with brainstem-cerebellar and thalamocortical vestibular networks and cortical sensorimotor networks. At the symptom peak (day 3 post UL), brain networks were found to be organized in large ensembles of distinct and highly connected hubs of brain regions, which separated again with progressing VC. Thus, we found rapid changes in network organization at the subcortical and cortical level and in both hemispheres, which may indicate an initial functional substitution of vestibular loss and subsequent recalibration and reorganization of sensorimotor networks during VC.
Topics: Adaptation, Physiological; Animals; Arsanilic Acid; Brain; Connectome; Fluorodeoxyglucose F18; Glucose; Locomotion; Neural Pathways; Neuronal Plasticity; Nystagmus, Pathologic; Positron-Emission Tomography; Postural Balance; Radiopharmaceuticals; Rats; Vestibular Diseases; Vestibule, Labyrinth
PubMed: 33249212
DOI: 10.1016/j.neuroimage.2020.117588 -
Water Research Jun 2020As a common animal feed additive, p-arsanilic acid (p-AsA) is thought to be excreted with little uptake and unchanged chemical structure, threatening the environment by...
As a common animal feed additive, p-arsanilic acid (p-AsA) is thought to be excreted with little uptake and unchanged chemical structure, threatening the environment by potentially releasing more toxic inorganic arsenic. We herein investigated the removal of arsenic by in situ formed ferric (oxyhydr)oxides with the promotion of p-AsA degradation in Fe(II)/peroxydisulfate (PDS) system. Results showed that under acid conditions, p-AsA degraded very quickly and over 99% of p-AsA (5 μM) was degraded within 10 min at the optimal dosage of Fe(II) (100 μM) and PDS (150 μM) at pH 3, while less than 66.4% of arsenic was removed at pH 3-5. Higher pH (3-7) would inhibit the degradation of p-AsA but promote the arsenic removal. At pH 6-7, over 98.5% of total arsenic was removed, while the degradation efficiency of p-AsA was lower than 52.4%. HPLC-ICP-MS results indicated that the arsenic group was cleaved from p-AsA in the form of As(III) and then rapidly oxidized to As(V). FTIR and XPS analysis indicated that both As(V) products and residual p-AsA were bonded to ferric (oxyhydr)oxides via hydroxyl groups. Common cations (e.g., Na, Ca, Mg) and anions such as Cl, SO, CO had no significant influence on arsenic removal, while SiO, PO and HA inhibited the removal of total arsenic, mainly by affecting the zeta potential of iron particles. In summary, the Fe(II)/PDS process, as an efficient method for partial oxidation and simultaneous adsorption of p-AsA under near-neutral conditions, is expected to control the potential environmental risks of p-AsA.
Topics: Adsorption; Animals; Arsanilic Acid; Arsenic; Ferric Compounds; Ferrous Compounds; Hydrogen-Ion Concentration; Iron; Oxidation-Reduction; Water Pollutants, Chemical
PubMed: 32283433
DOI: 10.1016/j.watres.2020.115752 -
ACS Applied Materials & Interfaces Dec 2020It is very significant that functional porous metal-organic frameworks are used to manufacture hierarchical components to achieve cascading functions that cannot be...
It is very significant that functional porous metal-organic frameworks are used to manufacture hierarchical components to achieve cascading functions that cannot be achieved by a single-layer metal-organic framework (MOF). Here, we report two cases of novel MOFs constructed by the same ligand, - and - (Htpt = 5-[4(1-1,2,4-triazol-1-yl)]phenyl-2-tetrazole), and prepared a --- by a layer-by-layer approach ignoring the lattice mismatch problem. The first - layer is grown on an oriented CuO nanostructured array by a "one-pot" approach. The aligned second - layer can be deposited using liquid-phase epitaxy. Notably, the prepared --- combines adsorption and fluorescence sensing, which exhibited significant adsorption for CrO (203.25 mg g) as typical highly poisonous ions with a fluorescence quenching response. Hence, based on the oxidation-reduction between CrO and -arsanilic acid (-ASA), the --- ability to adsorb CrO could be used to design "on-off-on" mode fluorescence probes to detect -ASA with high sensitivity (limit of detection (LOD) = 0.0556 μg L). -ASA can be degraded into highly toxic inorganic arsenic compounds in the natural environment and has received widespread attention. Therefore, the integration of adsorption and fluorescence properties makes the --- a feasible multifunctional material for pollution control and detection.
PubMed: 33345540
DOI: 10.1021/acsami.0c17875 -
The Science of the Total Environment Jan 2024Although banned in some countries, p-arsanilic acid (ASA) is still widely used as feed additive in poultry production. As a result, ASA is usually released into the...
Although banned in some countries, p-arsanilic acid (ASA) is still widely used as feed additive in poultry production. As a result, ASA is usually released into the aquatic environment without any treatments. Although ASA exhibits low toxicity, it can be transformed into highly toxic aromatic amines and inorganic arsenic species (As (V) as HAsO and HAsO) under natural environmental conditions. Hence, it is necessary to develop efficient technologies for its removal or degradation. In this contribution, electrochemical advanced oxidation technology with boron-doped diamond (BDD) had been initially used to degrade ASA pollutants. A five-level central composite rotatable design (CCRD) was implemented to optimize the various influencing factors involved, among applied current density, NaCl concentration, NaSO concentration and NaHCO concentration on the oxidation efficiency; the latter was assessed in terms of ASA degradation percentage. The results obtained highlighted the unique and important roles of electrolytes during the electrolytic oxidations. Meanwhile, the major degradation byproducts detected were also strongly dependent on the electrolyte adopted. In particular, several oligomer byproducts with novel structures were initially identified in BDD-treated ASA solutions. Two different electrochemical transformation pathways of ASA on BDD anode were thus proposed. This study demonstrated the effectiveness of BDD technology in the degradation of ASA, as well as the potential minor risk of its application in actual ASA wastewater treatment.
PubMed: 37797755
DOI: 10.1016/j.scitotenv.2023.167538 -
Materials (Basel, Switzerland) Dec 2023As a kind of emerging contaminant, organoarsenic compounds have drawn wide concern because of their considerable solubilities in water, and the highly toxic inorganic...
As a kind of emerging contaminant, organoarsenic compounds have drawn wide concern because of their considerable solubilities in water, and the highly toxic inorganic arsenic species formed during their biotic and abiotic degradation in the natural environment. Thus, the effective removal and studying of the adsorption mechanism of organoarsenic compounds are of significant urgency. In this work, MnFeO and MnFeO/graphene were prepared through a facile solvothermal method. From the results of the Transmission Electron Microscope (TEM) characterization, it can be found that MnFeO nanoparticles were uniformly distributed on the surface of the graphene. And the specific surface area of the MnFeO/graphene was about 146.39 m g, much higher than that of the MnFeO (86.15 m g). The interactions between organoarsenic compounds and adsorbents were conducted to study their adsorption behavior and mechanism. The maximum adsorption capacities of MnFeO/graphene towards p-arsanilic acid (p-ASA) and roxarsone (ROX) were calculated to be 22.75 and 30.59 mg g. Additionally, the ionic strength, negative ions, and humus were introduced to investigate the adsorption performance of organoarsenic compounds. Electrostatic adsorption and surface complexation are the primary adsorption mechanisms on account of X-ray photoelectron spectroscopy (XPS) and the Fourier-transform infrared spectroscopy (FT-IR) analysis. This research extends the knowledge into studying the interaction between organoarsenic species and hybrid nanomaterials in the natural environment.
PubMed: 38138778
DOI: 10.3390/ma16247636 -
Journal of Hazardous Materials Jul 2023Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, Rox(V)), an extensively used organoarsenical feed additive, enters soils through the application of Rox(V)-containing...
Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, Rox(V)), an extensively used organoarsenical feed additive, enters soils through the application of Rox(V)-containing manure and further degrades to highly toxic arsenicals. Microplastics, as emerging contaminants, are also frequently detected in soils. However, the effects of microplastics on soil Rox(V) degradation are unknown. A microcosm experiment was conducted to investigate soil Rox(V) degradation responses to polyethylene (PE) microplastics and the underlying mechanisms. PE microplastics inhibited soil Rox(V) degradation, with the main products being 3-amino-4-hydroxyphenylarsonic acid [3-AHPAA(V)], N-acetyl-4-hydroxy-m-arsanilic acid [N-AHPAA(V)], arsenate [As(V)], and arsenite [As(III)]. This inhibition was likely driven by the decline in soil pH by PE microplastic addition, which may directly enhance Rox(V) sorption in soils. The decreased soil pH further suppressed the nfnB gene related to nitroreduction of Rox(V) to 3-AHPAA(V) and nhoA gene associated with acetylation of 3-AHPAA(V) to N-AHPAA(V), accompanied by a decrease in the relative abundance of possible Rox(V)-degrading bacteria (e.g., Pseudomonadales), although the diversity, composition, network complexity, and assembly of soil bacterial communities were largely influenced by Rox(V) rather than PE microplastics. Our study emphasizes microplastic-induced inhibition of Rox(V) degradation in soils and the need to consider the role of microplastics in better risk assessment and remediation of Rox(V)-contaminated soils.
Topics: Roxarsone; Microplastics; Plastics; Soil; Polyethylene
PubMed: 37116328
DOI: 10.1016/j.jhazmat.2023.131483 -
Environmental Science and Pollution... May 2024The widespread used organoarsenicals have drawn attention for decades due to their potential environment risks. In this study, a heterogeneous system of goethite/oxalate...
The widespread used organoarsenicals have drawn attention for decades due to their potential environment risks. In this study, a heterogeneous system of goethite/oxalate irradiated using UVA light (λ = 365 nm) was applied for the removal of ASA, a kind of organoarsenicals used in animal feeding operations as additives, from the aqueous phase through photodegradation. Results showed that the presence of 5 mM of oxalate significantly enhanced the photodegradation efficiency of ASA in the 0.1 g/L of goethite suspended system from 28 to ~100% within 180 min reaction at pH 5. Acid conditions favored the photoreaction rate, compared with neutral and basic conditions. This reaction process was also influenced by the initial concentration of oxalate and ASA. Furthermore, the mechanism study was conducted by quenching experiments and revealed the important roles of ·OH in the degradation of ASA in the goethite/oxalate/UVA system. By analyzing the reaction products, both inorganic arsenic (As(III) and As(V)) and ammonia were detected during the photodegradation of ASA. These findings help to gain a better understanding of the geochemical behavior of ASA in surface water and can also provide a potential treatment method for the organoarsenicals contaminated water.
Topics: Ultraviolet Rays; Oxalates; Photolysis; Minerals; Iron Compounds; Arsanilic Acid; Water Pollutants, Chemical
PubMed: 37594713
DOI: 10.1007/s11356-023-29289-9 -
Chemosphere Dec 2023Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, Rox), a widely used organoarsenical feed additive, can enter soils and be further biotransformed into various arsenic...
Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, Rox), a widely used organoarsenical feed additive, can enter soils and be further biotransformed into various arsenic species that pose human health and ecological risks. However, the pathway and molecular mechanism of Rox biotransformation by soil microbes are not well studied. Therefore, in this study, we isolated a Rox-transforming bacterium from manure-fertilized soil and identified it as Pseudomonas chlororaphis through morphological analysis and 16S rRNA gene sequencing. Pseudomonas chlororaphis was able to biotransform Rox to 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA), N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), arsenate [As(V)], arsenite [As(III)], and dimethylarsenate [DMAs(V)]. The complete genome of Pseudomonas chlororaphis was sequenced. PcmdaB, encoding a nitroreductase, and PcnhoA, encoding an acetyltransferase, were identified in the genome of Pseudomonas chlororaphis. Expression of PcmdaB and PcnhoA in E. coli Rosetta was shown to confer Rox(III) and 3-AHPAA(III) resistance through Rox nitroreduction and 3-AHPAA acetylation, respectively. The PcMdaB and PcNhoA enzymes were further purified and functionally characterized in vitro. The kinetic data of both PcMdaB and PcNhoA were well fit to the Michaelis-Menten equation, and nitroreduction catalyzed by PcMdaB is the rate-limiting step for Rox transformation. Our results provide new insights into the environmental risk assessment and bioremediation of Rox(V)-contaminated soils.
Topics: Humans; Roxarsone; Pseudomonas chlororaphis; Soil; Acetyltransferases; RNA, Ribosomal, 16S; Escherichia coli; Arsenic; Biotransformation; Nitroreductases
PubMed: 37898462
DOI: 10.1016/j.chemosphere.2023.140558