Phenylarsonic Acid Compounds Research Articles

Autocatalytic effect of in situ formed (hydro)quinone intermediates in Fenton and photo-Fenton degradation of non-phenolic aromatic pollutants and chemical kinetic modeling

While the electron-shuttling properties of (hydro)quinones can facilitate the redox cycling of iron species (Fe2+ and Fe3+), the impact of in situ formed (hydro)quinones from degradation of non-phenolic aromatic pollutants in Fenton-type processes has not been reported. This study investigated the catalytic effect of (hydro)quinone intermediates produced from degradation of p-arsanilic acid (p-ASA) and roxarsone (ROX) in Fenton and photo-Fenton processes, and its chemical kinetic modeling. The bimolecular rate constants of the reactions of OH with p-ASA and ROX were determined to be (2.79 ± 0.29) × 109 and (2.03 ± 0.07) × 109 M−1·s−1, respectively. However, ROX degraded faster than p-ASA in Fenton process under the same conditions, which was attributed to the greater catalytic effect of the in situ formed (hydro)quinone intermediates. p-Hydroquinone, p-benzoquinone, and 1,2,4-benzenetriol were identified among the oxidation intermediates of p-ASA, while 2-nitrohydroquinone, 2-nitrobenzoquinone, 1,2,4-benzenetriol, and 2-hydroxy-benzoquinone were found for ROX oxidation. The autocatalytic degradation of p-ASA and ROX in Fenton and photo-Fenton processes could be well described by a chemical kinetic model after accounting for the reactions of the (hydro)quinone intermediates. Both experimental and modeling results consistently showed that the redox cycling of iron promoted by the in situ formed (hydro)quinone intermediates was critical for the oxidation of p-ASA and ROX in Fenton process. Chemical kinetic modeling revealed that (hydro)quinone-related reactions and photo-reduction of Fe3+-complexes were responsible for producing the vast majority of OH that sustained the continuous degradation of p-ASA and ROX in photo-Fenton process with the presence of limited amount of Fe2+. The autocatalytic effect observed for phenylarsonic acid compounds and the chemical kinetic model developed in this study could guide the development of Fenton and solar photo-Fenton treatment for other non-phenolic aromatic pollutants.

Removal of phenylarsonic acid compounds by porous nitrogen doped carbon: Experimental and DFT study

Phenylarsonic acids are deemed as emerging contaminants, and their removal by carbonaceous materials has aroused wide attentions. However, the adsorption behaviors and mechanisms on nitrogen doped carbon still remain unclear. Herein, nitrogen doped porous carbons (NC-x) for adsorbing p-arsanilic acid and roxarsone were fabricated by hydrothermal and following activation treatment of peanut shell. The results revealed that NC-750 which was activated at 750 °C exhibited high BET surface area of 1331.11 m2/g, total pore volume of 0.97 cm3/g and average pore size of 2.91 nm, and its maximum equilibrium capacities based on Sips model for p-arsanilic acid and roxarsone were 287.3 mg/g and 462.6 mg/g, respectively. The sufficient adsorption space, rich defect structure and high affinity of nitrogen-containing groups endow NC-750 with high adsorption capacities, and the adsorption mechanisms involve with pore-filling, hydrogen bonding and π-π interactions. Density functional theory (DFT) calculation demonstrated that p-arsanilic acid was electron donor while roxarsone was electron acceptor, and graphitic nitrogen was conducive to the π-π interactions while pyrrolic nitrogen and pyridinic nitrogen were preferential for hydrogen bonding interactions. This work can provide reference for understanding the adsorption behaviors and interfacial mechanisms between phenylarsonic acid and nitrogen doped carbonaceous materials.

Removal of Phenylarsonic Acid Compounds by Porous Nitrogen Doped Carbon: Experimental and Dft Study

Removal of Phenylarsonic Acid Compounds by Porous Nitrogen Doped Carbon: Experimental and Dft Study

Removal of p-arsanilic acid and phenylarsonic acid from water by Fenton coagulation process: influence of substituted amino group

Phenylarsonic acid compounds, which were widely used in poultry and swine production, are often introduced to agricultural soils with animal wastes. Fenton coagulation process is thought as an efficient method to remove them. However, the substituted amino group could apparently influence the removal efficiency in Fenton coagulation process. Herein, we investigated the optimal conditions to treat typical organoarsenic contaminants (p-arsanilic acid (p-ASA) and phenylarsonic acid (PAA)) in aqueous solution based on Fenton coagulation process for oxidizing them and capturing the released inorganic arsenic, and elucidated the influence mechanism of substituted amino group on removal. Results showed that the pH value and the dosage of H2O2 and Fe2+ significantly influenced the performance of the oxidation and coagulation processes. The optimal conditions for removing 20 mg L-1-As in this research were 40mg L-1 Fe2+ and 60mg L-1 H2O2 (the mass ratio of Fe2+/H2O2 = 1.5), initial solution pH of 3.0, and final solution pH of 5.0 adjusting after 30-min Fenton oxidation reaction. Meanwhile, the substituted amino group made p-ASA much more easily be attacked by ·OH than PAA and supply one more binding sites for forming complexes with Fe3+ hydrolysates, resulting in 36% higher oxidation rate and 7% better coagulation performance at the optimal conditions.

Adsorption and desorption of phenylarsonic acid compounds on metal oxide and hydroxide, and clay minerals

Adsorption and desorption of p-arsanilic acid (p-ASA) and roxarsone (ROX) on six soil minerals, including hematite (α-Fe2O3), goethite (α-FeOOH), ferrihydrite (Fe(OH)3), aluminum oxide (α-Al2O3), manganese oxide (γ-MnO2), and kaolinite, were studied, and the impact of solution matrices on their adsorption was systematically evaluated. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals occurred quickly (mostly within 2 h), and could be well described by the pseudo second-order kinetic model. The apparent maximum adsorption capacities of α-Fe2O3, α-FeOOH, Fe(OH)3, α-Al2O3, γ-MnO2, and kaolinite (at an initial pH of 7.0) for p-ASA were 1.7, 0.9, 2.5, 0.08, 1.1, and 0.02 μmol/m2, while those for ROX were 1.6, 0.7, 2.4, 0.1, 0.5, and 0.05 μmol/m2, respectively. Besides adsorbing p-ASA/ROX, γ-MnO2 also caused their oxidation. Experimental results suggest that formation of inner-sphere complexes through the arsonic acid group is the primary mechanism for adsorption of p-ASA/ROX on iron (hydro)oxides and γ-MnO2, while outer-sphere complexation plays a critical role in their adsorption on α-Al2O3 and kaolinite. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals was affected by solution pH, co-existing metal ions (Ca2+, Mg2+, Al3+, Cu2+, Fe3+, and Zn2+), oxyanions (H2PO4−, HCO3−, and SO42−), and humic acid. The solid-to-liquid partition coefficients of p-ASA during the desorption from α-Fe2O3, α-FeOOH, Fe(OH)3, α-Al2O3, γ-MnO2, and kaolinite were 0.47, 2.69, 4.38, 0.03, 30.4, and 0.1 L/g, while those of ROX were 0.28, 1.68, 3.48, 0.02, 4.0, and 0.02 L/g, respectively. Agricultural soils with lower contents of organic carbon exhibited higher adsorption capacities towards p-ASA/ROX, which indicates that soil minerals play a key role in the adsorption of phenylarsonic acid compounds while organic matter could have strong inhibitory effect. These findings could help better understand and predict the transport and fate of p-ASA/ROX in surface soils with low contents of organic matter.

Structure-Reactivity Relationships in the Adsorption and Degradation of Substituted Phenylarsonic Acids on Birnessite (δ-MnO2).

Phenylarsonic acid compounds could be oxidized by manganese oxides in surface soils, resulting in quick release of inorganic arsenic. This study investigated the structure-reactivity relationships in the adsorption and oxidative degradation of six substituted phenylarsonic acids on the surface of a major type of manganese oxides, birnessite (δ-MnO2), using batch experiments conducted under acidic to neutral conditions. The initial adsorption rates of the substituted phenylarsonic acids on δ-MnO2 decreased in the order of phenylarsonic acid (PAA) > 4-aminophenylarsonic acid (p-ASA) ≈ 2-aminophenylarsonic acid (2-APAA) > 4-hydroxyphenylarsonic acid (4-HPAA) > 2-nitrophenylarsonic acid (2-NPAA) > 4-hydroxy-3-nitrophenylarsonic acid (ROX), which could be attributed to steric hindrance of the substituents and the hydrophobicity of these compounds. The oxidation rates of these structural analogues by δ-MnO2 decreased in the order of p-ASA ≈ 2-APAA > 4-HPAA > ROX, while 2-NPAA and PAA were nonreactive because of the lack of electron-donating substituents on their aromatic rings. The redox reactivity of these compounds agrees well with the electron density at C1, which is determined by the types and position of the substituents on the aromatic ring. Although cleavage of the arsonic acid group from the aromatic ring was the predominant transformation pathway, a range of adduct products also formed through cross-coupling of the radicals and radical substitution. The contribution of radical coupling and substitution in overall degradation decreased in the order of p-ASA > 2-APAA > 4-HPAA > ROX, which results from the varying reactivity and steric hindrance of the substituents. These insights could help better understand and predict the fate of substituted phenylarsonic acids in manganese oxide-rich surface soils and the associated environmental risk of arsenic pollution.

Phenylarsonic acid compounds with broad-spectrum and potent cytotoxic activity against human cancer cells.

The in vitro cytotoxic activity profile of nine novel phenylarsonic acid (CAS 98-05-5, PAA) compounds against 17 human cancer cell lines including (a) ovarian cancer cell lines ES-2, PA-1, CAOV-3, OVCAR-3, (b) testicular cancer cell lines Ntera-2, Tera-2, N2NICP, 833K, and 64CP, (c) multiple myeloma cell lines ARH77, HS-Sultan, RPMI-8226, and U266, and (d) acute lymphoblastic leukemia (ALL) cell lines NALM-6, MOLT-3, ALL-1, and RS4; 11, was determined by the MTT assay. The lead compounds, 2-methylthio-4-[(4'-aminophenylazo)-phenylarsonic acid] pyrimidine (PHI-370) and 2-methylthio-4-(4'-phenylarsonic acid)-aminopyrimidine (PHI-380) caused apoptotic death in all 17 cancer cell lines at low micromolar concentrations, as documented by TUNEL assays and confocal laser scanning microscopy. PHI-380 was also tested and found to be very active against primary tumor cells isolated from surgical biopsy specimens of 14 patients with therapy-refractory non-small cell lung cancer, breast cancer, colon cancer, lymphoma, hepatoblastoma, or Wilm's tumor as well. Because of their broad-spectrum and potent anticancer activity and ability to induce apoptosis in primary tumor cells from therapy-refractory cancer patients, PAA compounds such as PHI-370 and PHI-380 may provide the basis for effective salvage regimens for patients with recurrent cancer.

Phenylarsonic Acid Compounds with Broad‐Spectrum and Potent Cytotoxic Activity Against Human Cancer Cells.

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Organic Phenyl Arsonic Acid Compounds with Potent Antileukemic Activity

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Organic phenyl arsonic acid compounds with potent antileukemic activity

A series of 12 organic arsonic acid compounds has been synthesized and evaluated against human B-lineage (NALM-6) and T-lineage (MOLT-3) acute lymphoblastic leukemia (ALL) cell lines. The lead compounds 2-trichloromethyl-4-[4′-(4″-phenylazo)phenylarsonic acid]aminoquinazoline (compound 19, PHI-P518; IC 50=1.1±0.5 μM against NALM-6 and 2.0±0.8 μM against MOLT-3) and 2-methylthio-4-(2′-phenylarsonic acid)aminopyrimidine (compound 15, PHI-P381; IC 50=1.5±0.3 μM against NALM-6 and 2.3±0.5 μM against MOLT-3) exhibited potent antileukemic activity at low micromolar concentrations.

Effect of Cupric Sulfate on the Prophylactic Efficacy of 2-Acetylamino-5-Nitrothiazole, Nifursol and Ipronidazole against Histomoniasis in Turkeys ,

BOWEN and Sullivan (1971) and Bowen et al. (1971) reported certain effects of dietary cupric sulfate (0.025, 0.05 or 0.10%) in young turkeys. Body weight gain was decreased when cupric sulfate was added to diets containing 22 parts per million (p.p.m.) of penicillinstreptomycin, 1:3. It would appear that high levels of cupric sulfate interfered with the growth promoting activity of penicillin and/or streptomycin. In another study, dietary cupric sulfate additions significantly (P<0.05) reduced the prophylactic efficacy of three phenylarsonic acid compounds against histomoniasis in young turkeys.Several non-arsonic acid compounds have proven effective for prevention and treatment of histomoniasis. Nifursol, 2-acetylamino-5-nitrothiazole and ipronidazole are three such compounds. Jungherr and Winn (1950), McGregor (1952) and Grumbles et al. (1952) have shown that 0.05 to 0.10 percent of 2-acetylamino-5-nitrothiazole in the diet would in most instances prevent histomoniasis lesions and mortality. The recommended level of 2-acetylamino-5-nitrothiazole for the prevention of…

Effect of Long-Time Feeding of Certain Arsonic Acids to Chickens

IN RECENT years, it has been shown that certain phenylarsonic acid compounds increase growth rate in young chickens and turkeys (Frost 1953; Morehouse 1949). Sometimes the growth response has been in addition to that provided by antibiotics and sometimes it has not (Bird, 1952a). The exact mode of action of these compounds in promoting growth is unknown but indications are that the beneficial effects result from their action upon the intestinal microflora —as is the case with antibiotics.In applying these findings to practical feeds two arsenicals have been incorporated generally in commercial broiler feeds —3-nitro-4-hydroxyphenylarsonic acid (“3-nitro”) and p-amino phenylarsonic acid (arsanilic acid). Although these chemicals would do the same for flock-replacement pullets as for broilers, they have not been used much for the growing flock because there is less interest in fast, early growth and improved pigmentation in birds intended for egg production.Very little research has been …