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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 -
Journal of Colloid and Interface Science May 2020Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into...
HYPOTHESIS
Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into the environment. Bimetal ferrites are recognized as promising sorbents in removal of organoarsenicals with formation of FeOAs complexes, and their high saturation magnetization also allows easy sorbent separation.
EXPERIMENTS
Herein, a flower-like CoFeO sorbent was synthesized through an environmental-friendly process.
FINDINGS
The flower-like CoFeO particles have abundant mesopores and a large specific surface area of 48.4 m/g. At an equilibrium concentration of 80 μmol/L, the sorption capacities towards p-arsanilic acid (p-ASA), roxarsone (ROX), 4-hydroxyphenylarsonic acid (4-HPAA), 2-aminophenylarsonic acid (2-APAA), phenylarsonic acid (PAA), and 2-nitrophenylarsonic acid (2-NPAA) were 38.1, 45.7, 38.7, 39.3, 33.0, and 32.8 mg/g, respectively. Langmuir model and pseudo-second-order kinetics could well fit the sorption isotherms and rates. The sorption performance was better under acidic conditions due to enhanced electrostatic attraction. Humic acid (HA) and PO inhibited the sorption through competing for sorption sites, while Fe promoted sorption due to formation of additional FeOAs complexes on sorbent surface. The experimental observations, spectroscopic insights, and density functional theory (DFT) calculations consistently indicate that the sorption of aromatic organoarsenicals on the flower-like CoFeO particles occurs mainly through formation of inner-sphere complexes. The flower-like CoFeO could be regenerated and reused over multiple cycles. The high sorption capacities, together with its magnetic property, make the flower-like CoFeO an attractive sorbent for removing aromatic organoarsenicals from wastewater.
PubMed: 32087406
DOI: 10.1016/j.jcis.2020.02.004 -
Environmental Science and Pollution... Apr 2020Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a...
Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a heterogeneous Fenton process mediated by SiO-coated nano zero-valent iron (SiO-nZVI) was employed to simultaneously remove the p-arsanilic acid (p-ASA, a typical organoarsenic compound) and the released arsenic. The initial pH value significantly influenced on the degradation of p-ASA and at the optimal pH (3.0), p-ASA (10 mg L) could be completely oxidized to As(V), NH, and plentiful phenolic compounds such as phenol and p-hydroquinone via the cleavage of C-N and C-As bonds within 60 min in pure water. Meanwhile, although the formed lepidocrocite and magnetite on the surface of SiO-nZVI significantly limited the reutilization, they played a vital role in the adsorption of the released As(V) and the residual arsenic levels in the effluent were as low as 0.031 mg L, meeting both the drinking water standard of the World Health Organization (WHO) and the surface water standard of China (0.05 mg L). Furthermore, high-level dissolved organic matters (DOM) (> 2 mg C L) exhibited strong interference with both the oxidation of p-ASA and adsorption of arsenic, but the interference could be eliminated by increasing the SiO-nZVI dosage or adding HO. Importantly, this system could completely remediate p-ASA in a short time and simultaneously avoid the secondary pollution caused by inorganic arsenic, which was significant for the remediation of organoarsenic pollutants in swine wastewater.
Topics: Animals; Arsenic; China; Hydrogen Peroxide; Iron; Silicon Dioxide; Swine; Water Pollutants, Chemical
PubMed: 31983004
DOI: 10.1007/s11356-020-07808-2 -
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 -
Applied and Environmental Microbiology Jan 2020The organoarsenical feed additive 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone [ROX]) is widely used and released into the environment. We previously showed a...
-Hydroxyarylamine -Acetyltransferases Catalyze Acetylation of 3-Amino-4-Hydroxyphenylarsonic Acid in the 4-Hydroxy-3-Nitrobenzenearsonic Acid Transformation Pathway of sp. Strain CZ-1.
The organoarsenical feed additive 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone [ROX]) is widely used and released into the environment. We previously showed a two-step pathway of ROX transformation by sp. strain CZ-1 involving the reduction of ROX to 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) and the acetylation of 3-AHPAA to -acetyl-4-hydroxy--arsanilic acid (N-AHPAA) (K. Huang, H. Peng, F. Gao, Q. Liu, et al., Environ Pollut 247:482-487, 2019, https://doi.org/10.1016/j.envpol.2019.01.076). In this study, we identified two genes ( and ), encoding -hydroxyarylamine -acetyltransferases, as responsible for 3-AHPAA acetylation in sp. strain CZ-1. The results of genetic disruption and complementation showed that both genes are involved in ROX biotransformation and that is the major 3-AHPAA acetyltransferase gene. Quantitative reverse transcription-PCR analysis showed that the relative expression level of was 3-fold higher than that of Each of the recombinant NhoAs was overexpressed in BL21 and homogenously purified as a dimer by affinity chromatography. Both purified NhoAs catalyzed acetyl coenzyme A-dependent 3-AHPAA acetylation. The values of 3-AHPAA for NhoA1 and NhoA2 were 151.5 and 428.3 μM, respectively. Site-directed mutagenesis experiments indicated that two conserved arginine and cysteine residues of each NhoA were necessary for their enzyme activities. Roxarsone (ROX) is an organoarsenic feed additive that has been widely used in poultry industries for growth promotion, coccidiosis control, and meat pigmentation improvement for more than 70 years. Most ROX is excreted in the litter and dispersed into the environment, where it is transformed by microbes into different arsenic-containing compounds. A major product of ROX transformation is -acetyl-4-hydroxy--arsanilic acid (N-AHPAA), which is also used as a clinical drug for treating refractory bacterial vaginosis. Here, we report the cloning and functional characterization of two genes encoding -hydroxyarylamine -acetyltransferases, NhoA1 and NhoA2, in sp. strain CZ-1, which catalyze the acetylation of 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) formed by the reduction of ROX to N-AHPAA. This study provides new insights into the function of -hydroxyarylamine -acetyltransferase in the transformation of an important organoarsenic compound.
Topics: Acetylation; Acetyltransferases; Arsenicals; Bacterial Proteins; Enterobacter; Metabolic Networks and Pathways
PubMed: 31676473
DOI: 10.1128/AEM.02050-19 -
Journal of Hazardous Materials Feb 2020Organoarsenicals have been used in poultry production for years, however, studies focused on roxarsone (ROX), with little attention to p-arsanilic acid (ASA). We...
Organoarsenicals have been used in poultry production for years, however, studies focused on roxarsone (ROX), with little attention to p-arsanilic acid (ASA). We assessed arsenic (As) concentration and speciation in chicken meat collected from 10 cities in China. The geometric mean for total As in 249 paired raw and cooked samples was 4.85 and 7.27 μg kg fw, respectively. Among 81 paired raw and cooked samples, ASA and ROX were detected in >90% samples, suggesting the prevalence of organoarsenical use in China. ASA contributed the most (45% on average) to total As in cooked samples, followed by As(V), DMA, As(III), and ROX (7.2-22%). ASA was found to contribute more to total As in chicken meat compared to ROX for the first time. Arsenic in chicken meat showed considerable geographic variation, with higher inorganic arsenic (iAs) being detected from cities with higher ROX and ASA, indicating that organoarsenical use increased iAs concentration in chicken meat. When health risk was estimated, dietary exposure to iAs would result in an increase of 3.2 bladder and lung cancer cases per 100,000 adults. The result supports the removal of organoarsenicals in poultry production from Chinese market and further supports its removal from the global markets.
Topics: Animals; Arsanilic Acid; Arsenic; Arsenicals; Chickens; China; Meat; Roxarsone
PubMed: 31525688
DOI: 10.1016/j.jhazmat.2019.121178 -
Journal of Colloid and Interface Science Oct 2019Arsenic species are regarded as typical water pollutants due to their toxicity. The chemical structures of arsenic species greatly influence their migration and...
Arsenic species are regarded as typical water pollutants due to their toxicity. The chemical structures of arsenic species greatly influence their migration and transformation in the environment. Metal-organic frameworks (MOFs) are used as reliable adsorbents to control arsenic contamination, so it is urgently needed to study the effect of chemical structure of arsenic species during adsorption process. The adsorption behaviors of arsenate (As(V)) and its organic forms such as roxarsone (ROX), p-arsanilic acid (p-ASA) and dimethyl arsenate (DMA) by MIL-101(Fe), a type of highly porosity iron-based MOFs in aqueous environment were detailed investigated. The adsorption kinetics of those arsenic species on MIL-101(Fe) is rapid followed with pseudo-second-order kinetic model. MIL-101(Fe) exhibits excellent adsorption capacities for As(V), ROX, p-ASA and DMA with maximum adsorption capacities of 232.98, 507.97, 379.65 and 158.94 mg g, respectively. The formed FeOAs inner-sphere coordination between arsenic species and the incomplete-coordinated cationic Fe in the MIL-101(Fe) cluster is the primary adsorption mechanism based on FTIR and XPS analysis. Substituent aromatic units in ROX and p-ASA strengthen the adsorption on MIL-101(Fe) through hydrogen bonds and π-π stacking interaction, resulting in higher adsorption capacities far beyond that of As(V) and DMA. The reusability of MIL-101(Fe) is limited by the strong FeOAs coordination. These results confirm MIL-101(Fe) a reliable adsorbent to control the aqueous arsenic species contamination and emphasize the significant role of the chemical structure of arsenic speciation on adsorption performances of MOFs.
PubMed: 31352244
DOI: 10.1016/j.jcis.2019.07.046