Chemistry Of Arsenic Research Articles

Data mining of arsenic-based small molecules geometrics present in Cambridge structural database

Arsenic, ubiquitous in various industrial processes and consumer products, presents both essential functions and considerable toxicity risks, driving extensive research into safer applications. Our investigation, drawing from 7182 arsenic-containing molecules in the Cambridge Structural Database (CSD), outlines their diverse bonding patterns. Notably, 51% of these molecules exhibit cyclic connections, while 49% display acyclic ones. Arsenic forms eight distinct bonding types with other elements, with significant interactions observed, particularly with phenyl rings, O3 and F6 moieties. Top interactions involve carbon, nitrogen, oxygen, fluorine, sulfur, and arsenic itself. We meticulously evaluated average bond lengths under three conditions: without an R-factor cut-off, with R-factor ≤0.075, and with R-factor ≤0.05, supporting the credibility of our results. Comparative analysis with existing literature data enriches our understanding of arsenic's bonding behaviour. Our findings illuminate the structural attributes, molecular coordination, geometry, and bond lengths of arsenic with 68 diverse atoms, enriching our comprehension of arsenic chemistry. These revelations not only offer a pathway for crafting innovative and safer arsenic-based compounds but also foster the evolution of arsenic detoxification mechanisms, tackling pivotal health and environmental challenges linked to arsenic exposure across different contexts.

Evaluation of Different Extractants to Estimate Bioavailable Arsenic in Soil

ABSTRACT Owing to the similar chemistry of phosphorus (P) and arsenic (As), sodium bicarbonate (0.5 N NaHCO3) is commonly used to extract plant accessible As in soil. This extractant has neither been tested widely in relation to plant As, nor is this extractant compatible with inductively coupled plasma mass spectrometry (ICP-MS) due to the high concentration of dissolved solid. Subsequently, it is of utmost important to design a suitable chemical extraction method in order to estimate plant available As compatibility with ICP-MS. For this purpose, paired soil and plant samples were collected from paddy fields located in Nadia, West Bengal, India. Soil was extracted with 0.5 M NaHCO3, 0.1 N and 0.5 N phosphoric acid (H3PO4), 0.1 N and 0.5 N sulfuric acid (H2SO4), 0.1 N, 0.5 N, 1.0 N, 1.5 N HNO3 and 0.01 M calcium chloride (CaCl2) solution. Arsenic extracted with NaHCO3, H3PO4 and H2SO4 was determined in hydride generation-atomic absorption spectrophotometer (HG-AAS), while ICP-MS served to determine As extracted from soil with HNO3. Olsen-extractable As in soils ranged from 0.48 to 3.57 mg kg−1 with a mean value of 1.45 mg kg−1. The extractable As content in soil varied from 0.01 to 10.1 mg kg−1 across the extractants. In the case of grain As, 0.1 N H3PO4, 0.5 N NaHCO3 and 1.5 N HNO3 extractable As had distinctly higher correlation coefficients (r = 0.49**, r = 0.47**, r = 0.45**) when compared to other extractants. More or less similar relationships of extractable As were obtained with straw As content like that of rice grain. In view of rapidity of the soil test method for As, 1.5 N HNO3 can be recommended for assessing available As in soil.

Prospects on arsenic remediation using organic cellulose-based adsorbents

During the past few years, among the most pressing issues afflicting humanity worldwide has been a lack of access to safe drinking water. Arsenic is thought to be one of the most dangerous contaminants in water bodies, that can cause cancer and is a major environmental concern. This necessitates a substantial amount of investigation to identify innovative techniques for detoxifying water at a cheaper cost, reducing the utilization of toxic chemicals and adverse environmental effects. Recently, researchers have become increasingly interested in using cellulose-based adsorbents to remove arsenic from wastewater. Cellulose is attracting recognition owing to its brilliant physical, chemical, and mechanical characteristics. In addition, cellulose has numerous hydroxyl groups on its surface, which makes it easy to incorporate chemical moieties and enhances its ability to adsorb pollutants. This review is an attempt to emphasize the potential of cellulose-based materials for radically altering the state of the art in the study of arsenic adsorption. In addition, the chemistry of arsenic, the risks that arsenic poses to human health, as well as the ouster of arsenic by modified cellulose, have all been thoroughly investigated and discussed. Furthermore, obstacles to advancing this technology, prospects, and cost analysis are comprehensively explored. It is apparent from the literature search that cellulose-based adsorbents demonstrate excellent capability for arsenic adsorption. However, it is still necessary to determine the commercial application of these adsorbents, which would lead to an improvement in pollution control.

Arsenic chemistry in municipal sewage sludge dewatering, thermal drying, and steam gasification: Effects of Fenton-CaO conditioning

In sludge disposal, Arsenic (As) poses serious secondary pollution due to its high toxicity and low stability. This work systematically studied the effects of Fenton-CaO composite conditioning on As chemistry throughout sludge dewatering, thermal drying, and steam gasification processes. The experimental results showed that, for raw sludge, 40.9% of As was released with filtrate discharging and 26.8–57.3% emitted with flue gas emission. When sludge was conditioned by Fenton-CaO, all of the As in the filtrate was fixed in the sludge cake and the releasing rate of gaseous As was reduced by up to 86.0%. Furthermore, the comprehensive results of the model compounds experiment, sequential extraction, and thermodynamic calculations revealed the effects of Fe/Ca conditioners on As species evolution. In the Fenton pre-oxidation, As(V) was reduced to As(III) due to the decreasing Eh caused by the excessive Fe(II). After adding CaO, As(III)/DMA (dimethyl arsenic) was adsorbed onto the surface of amorphous Fe(OH)3 that was introduced by Fenton's reagent, 50% and 43% of which were then oxidized or demethylated to form As(V)/MMA (monomethyl arsenic), respectively. In the following drying process at 120–180 °C, the FeOOH and CaO derived by residual Fe/Ca conditioners could promote the oxidation of 30% of the rest As(III) by the catalytic effect or directly reacting with it. In the final steam gasification process, the very little As(III) left in the dry sludge was released with the gas phase and the proportion of As(V) in gasification ash almost reached 100%. In short, Fenton-CaO composite conditioning could achieve the near-zero emission of As and reduce the toxicity of the products throughout the whole sludge treatment process.

Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects.

The discovery of the first isolable N-heterocyclic carbene in 1991 ushered in a new era in coordination chemistry. The remarkable bonding properties of carbenes have led to their rapid proliferation as auxiliary ligands for a wide range of transition metals and main group elements. In the case of group 15, while carbene-stabilized nitrogen and phosphorus compounds are extensively studied, the scope of research has shrunk significantly from arsenic to bismuth. This is essentially attributed to the decrease in stability of the C-E bond upon descending the group. Even so, modulating the carbene backbone or introducing alternative synthetic strategies not only alleviates the stability issues but also offers promising results in terms of the bonding and reactivities of these compounds. The purpose of the present perspective is to provide a comprehensive overview of the origins and development of carbene chemistry of arsenic, antimony, and bismuth, as well as to highlight the future prospects of this field.

Hazardous Effects of Arsenic Contaminated Water on the Biological Characteristics of Fishes: A Review

The aim of the current review is to deliberate on arsenic chemistry, its existence in aquatic ecosystem and its effects on the biological systems of fishes which are regarded as potential indicators for any change in water quality. Water is a major storehouse of arsenic which is present in the form of arsenate and arsenite. Anthropogenic activities including unlimited application of arsenic pesticides, industrial activities and mining operations have increased the universal incidence of soluble arsenic above tolerable levels of 0.010 mg/L. Variations in fish behaviour, growth rate, haematological and biological parameters and organ systems have been observed in arsenic contaminated water. Data regarding these parameters indicate that the fish shows aggressive behaviour and its weight increases due to a high arsenic uptake. The production rate of biochemical compounds like carbohydrates, proteins and lipids is reduced due to arsenic bonding with their precursors. Among organ systems, skin is a highly affected organ, while muscles are the least affected due to high arsenic concentration. Low concentration of arsenic results in bioaccumulation, conspicuously in liver and kidney, upon incessant exposure to freshwater fish. This bioaccumulation turns into biomagnification and becomes the cause of lethal diseases in human beings, such as hyperglycaemia, diminution of enzymatic activities and immune system abnormalities. Keeping in view all of these above mentioned facts, it is imperative to take action against excessive arsenic usage and to develop its eco-friendly management ways.

Tuning the Structure, Stability, and Responsivity of Polymeric Arsenical Nanoparticles Using Polythiol Cross-Linkers

The use of organic arsenicals in polymer chemistry and biomaterials science is limited despite the distinctive and versatile chemistry of arsenic. The interchangeable oxidation states of arsenic and the subsequent changes in chemical properties make it a promising candidate for redox-responsive materials. Thus, reversible addition–fragmentation chain transfer (RAFT) polymerization has been employed for the first time to synthesize thermoresponsive organic arsenical containing block copolymers. The polymers undergo simultaneous self-assembly and cross-linking, via the organic arsenical pendant groups, under reductive conditions (to reduce As(V) to As(III)) in the presence of polythiol reagents as cross-linkers. The formation of As–S bonds stabilizes the nanoparticles formed (Dh = 19–29 nm) and enables the stability and responsivity to oxidative stress of the particles, in aqueous and model biological solutions, to be tuned as a function of the number of thiols in the cross-linker or the [SH]/[As] stoichiometric ratio. The parent block copolymers and nanoparticles are nontoxic in vitro, and the tunable responsivity of these nanoparticles and the (bio)chemical activity of organic arsenical reagents could be advantageous for targeted drug delivery and the other bio(nano)medical applications. To the best our knowledge, this is the first time that arsenic–thiolate (As–S) bonding has been employed for stimuli-responsive cross-linking of polymeric nanoparticles.

Arsenic Removal Using "Green" Renewable Feedstock-Based Hydrogels: Current and Future Perspectives.

In the recent times, scanty access to clean water has been one of the most prevalent problems, affecting humankind throughout the world. This calls for a tremendous amount of research to recognize new methods of purifying water at lower cost, minimizing the use of hazardous chemicals and impact on the environment. The interest of the scientific community in the potential applications of renewable feedstock-based hydrogels for heavy-metal adsorption for water remediation has been continuously increasing during the last few decades. This study is an effort to highlight the application of hydrogels for revolutionizing the present research on heavy-metal adsorption, particularly arsenic. Besides, the arsenic chemistry, health hazards of arsenic to human health, and adsorption of arsenic by natural polymer-based hydrogels have been reviewed in detail. In addition, challenges in taking the hydrogel technology forward and future prospectives like cost, handling, and disposal of the adsorbent have been discussed systematically.

Conventional as well as Emerging Arsenic Removal Technologies—a Critical Review

Arsenic poisoning from contaminated drinking water has evolved as one of the major health hazards in recent times. High concentrations of arsenic in water and soil have been found in many parts of the world. Developing countries like Taiwan, Chile, Argentina, Bangladesh, Nepal and Vietnam are most affected by the contamination of groundwater with arsenic. These countries also cannot afford expensive and large-scale treatments to remove arsenic from drinking waters to acceptable limits (10 ppb, as recommended by WHO and US EPA). The aim of this review is to summarize low-cost, effective conventional technologies currently described in the literature for arsenic removal that can be used in the third world and developing countries, compare them with the emerging technologies and discuss their advantages and disadvantages along with a brief analysis of arsenic chemistry.

Review: Arsenic Remediation by Synthetic and Natural Adsorbents

The contagion of toxic metals in water is a serious environmental and health concern and threatening problem worldwide. Particularly arsenic contamination in ground water has became great dilemma in the earlier decades. With advent in research for arsenic remediation, standard of drinking water is improving and now reduced to few parts per million (ppm) level of arsenic in drinking water sources. However, due to continuous enhancement in environmental pollution, remediation techniques are still needed to achieve the drinking water quality standard. Development of novel and economically feasible removal techniques or materials for selective separation of this toxic specie has been the main focus of research. Several arsenic removal techniques, including membrane separation, coagulation, precipitation, anion exchange have been developed. The aim of this article is to review briefly arsenic chemistry and previous and current available technologies that have been reported various low-cost adsorbents for arsenic removal.

Toxicology of arsenic in fish and aquatic systems

Arsenic (As) is found in waters such as seawater, warm springs, groundwater, rivers, and lakes. In aquatic environments, As occurs as a mixture of arsenate and arsenite, with arsenate usually predominating. The unrestricted application of As pesticides, industrial activities, and mining operations has led to the global occurrence of soluble As above permissible levels of 0.010 mg/L. Continuous exposure of freshwater organisms including fish to low concentrations of As results in bioaccumulation, notably in liver and kidney. As a consequence As induces hyperglycemia, depletion of enzymatic activities, various acute and chronic toxicity, and immune system dysfunction. Here we review arsenic chemistry, the occurrence of arsenic in aquatic system, the transformation and metabolism of arsenic; arsenic bioaccumulation and bioconcentration; behavioral changes; and acute and other effects such as biochemical, immunotoxic, and cytogenotoxic effects on fish.

Recent advances in arsenic trioxide encapsulated nanoparticles as drug delivery agents to solid cancers.

Since arsenic trioxide was first approved as the front line therapy for acute promyelocytic leukemia 25 years ago, its anti-cancer properties for various malignancies have been under intense investigation. However, the clinical successes of arsenic trioxide in treating hematological cancers have not been translated to solid cancers. This is due to arsenic's rapid clearance by the body's immune system before reaching the tumor site. Several attempts have henceforth been made to increase its bioavailability toward solid cancers without increasing its dosage albeit without much success. This review summarizes the past and current utilization of arsenic trioxide in the medical field with primary focus on the implementation of nanotechnology for arsenic trioxide delivery to solid cancer cells. Different approaches that have been employed to increase arsenic's efficacy, specificity and bioavailability to solid cancer cells were evaluated and compared. The potential of combining different approaches or tailoring delivery vehicles to target specific types of solid cancers according to individual cancer characteristics and arsenic chemistry is proposed and discussed.

Adding a new dimension to the chemistry of phosphorus and arsenic.

The recently discovered phosphorenes are emerging as promising 2D materials for nanoelectronics. Novel structures and topologies can produce new properties and functionalities, and pave the way for potential new applications. For the first time, we predict two novel highly stable free-standing 2D monolayers of P and As with exotic hypercoordination motifs. This is the first hexacoordinate P and planar hexacoordinate As extended sheet. Ab initio calculations and molecular dynamics simulations demonstrate that these new Cu2X (X = P/As) materials are highly stable and are diamagnetic and metallic. Cu2P is slightly buckled without magnetism. For Cu2As, the exactly planar motif is the ground state. We observe an interesting phenomenon, i.e., buckling quenching of the magnetism in a 2D crystal. To our knowledge, this is the first example of buckling quenching of the magnetism in a 2D crystal. These results add a new dimension to the chemistry of phosphorus and arsenic.

Chemistry of Arsenic in Semi-Arid Alkaline Soils of the Southern High Plains, USA: Sorption Characteristics and Interactions with Soil Constituents

Limited information is available on the chemistry of arsenic (As) in the semi-arid alkaline soils of the Southern High Plains (SHP), USA. This study examined As sorption characteristics and its interactions with soil constituents in important agricultural soils (Amarillo, Arvana, Patricia, and Pullman) of the SHP using sorption isotherm models and sequential fractionation techniques. Results from fractionation of As into five distinct pools showed that about 52.4 % of the added As was found in the exchangeable and non-adsorbed pool in the Amarillo soil, suggesting this soil could have the highest tendency to release sorbed As to the environment, whereas the Pullman soil exhibited the greatest capacity to fix As as over 45 % of the added As was found in the residual fraction. The distribution of As among the soil constituents was a reflection of the characteristics of these soils. Arsenic sorption behaviors were well described by both the Freundlich and Langmuir models. Arsenic sorption maxima (q max) was highest in the Amarillo soil (~2124 mg kg−1), followed by the Pullman, Arvana, and Patricia soils with q max values of 1692, 1370, and 1317 mg kg−1, respectively. The Freundlich distribution coefficient (K d) was highest in the Pullman soil (21.6 L kg−1) and lowest in the Amarillo (1.38 L kg−1). Sorption parameters such as K d, N (sorption intensity constant) and qmax, varied among the soils, and the variability associated with K d and N in these semi-arid soils was explained by soil properties such as pH, organic matter, calcium carbonate, total free iron (Fe), sand, clay, total aluminum, total Fe, and total manganese contents. Findings from this study are important in understanding the environmental fate of As in semi-arid/arid climates and could be extended to other regions with similar soil characteristics.

Arsenic in the Soil Environment: Mobility and Phytoavailability

Abstract This review provides insights on (1) the chemistry of arsenic (As) in the soil environment and factors (e.g., pH, presence, nature, and concentration of competing inorganic and organic ligands), which regulate the sorption/desorption of arsenate and arsenite (the most abundant As species in soils and waters) on/from soil components; (2) the chemical fractionation and speciation of As to identify species that are more mobile and phytoavailable; and finally (3) the uptake of As by selected edible plants and production techniques able to reduce its translocation in plant tissues.

Chemistry, mineralogical, and residence of arsenic in a typical high arsenic coal

The arsenic chemistry, mineral association and distributions in coal were evaluated using density fraction and a low temperature ashing process. A high arsenic coal from Guizhou province in southwestern China was chosen in the study. The results show that light mineral (<2.89g/cm3) fraction and heavy mineral (>2.89g/cm3) fraction were successfully separated from Guizhou coal by means of the process. Phase-mineral composition in low temperature ash and light mineral fraction are almost the same, mostly quartz and kaolinite. In contrast, pyrite dominates in the heavy mineral fraction. Arsenic concentration in Guizhou coal is as high as 265μg/g. An obvious enrichment of arsenic in heavy mineral fraction is observed, and the arsenic concentration is approaching to 650μg/g. Modes of occurrence of arsenic exhibit as multiple forms. Both organic and inorganic associated arsenic in Guizhou coal have been identified. The organic associated arsenic accounts for 28.40% (wt.%) of the total arsenic. The inorganic associated arsenic mostly occurs in pyrite. Direct evidence by using the EDX analysis on 27 pyrite particles confirms that arsenic is occurring in pyrite. Each distinct pyrite particle contains a certain amount of arsenic with an average of 3.5% (wt.%), while the maximum is reaching to 6.7% (wt.%). Endemic arseniasis is highly suspected to be link to the frequent use of coal-burning stove for heating and/or food drying, inhalation of indoor air polluted by arsenic derived from coal combustion in houses, and the contaminated water in Guizhou province, southwestern China.

Soil Profile Arsenic Concentration Distributions in Missouri Soils Having Cambic and Argillic Soil Horizons

Understanding of the pedogenic pathways associated with arsenic (As) transformations in soil is important to understanding arsenic soil chemistry and discriminating between natural background and anthropogenic arsenic (As). Twenty-one soil series, some with multiple pedons, were assessed to determine if the As distributions in soil profiles exhibit discrete maxima that correspond to the presence of agrillic horizons. The majority of pedons exhibiting argillic horizon expression show a Fe-oxyhydroxide and As maxima corresponding precisely with the argillic horizon. Pearson correlation coefficients verify the close correspondence of Fe and As. Soil profiles having cambic horizons, and lacking argillic horizons, may also show As and Fe accumulations at soil depths. Some coarse-textured, well-drained to moderately well-drained Entisols and Inceptisols have Fe-oxyhydroxide accumulation in their cambic horizons, promoting As accumulation. Conversely, silty-textured and poorly drained to somewhat poorly drained Entisols and Inceptisols have C and Cg horizons that show somewhat uniform Fe and As concentrations throughout their soil profiles. Analysis of selected pedons having well-drained to moderately well-drained soil profiles demonstrates that clay fraction Fe and As concentrations are closely correlated and that the As and Fe concentrations are greater than those from the corresponding whole soil. The somewhat poorly drained Crowley pedon exhibited cohesive masses of Fe and Mn accumulation (sand separate) that had greater arsenic concentrations than those of the clay and silt separates. These pedogenic nodules with enhanced arsenic concentrations reveal alternative pathways involving arsenic transformation.

Arsenic(III) and iron(II) co-oxidation by oxygen and hydrogen peroxide: Divergent reactions in the presence of organic ligands

Iron-catalyzed oxidation of As(III) to As(V) can be highly effective for toxic arsenic removal via Fenton reaction and Fe(II) oxygenation. However, the contribution of ubiquitous organic ligands is poorly understood, despite its significant role in redox chemistry of arsenic in natural and engineered systems. In this work, selected naturally occurring organic ligands and synthetic ligands in co-oxidation of Fe(II) and As(III) were examined as a function of pH, Fe(II), H2O2, and radical scavengers (methanol and 2-propanol) concentration. As(III) was not measurably oxidised in the presence of excess ethylenediaminetetraacetic acid (EDTA) (i.e. Fe(II):EDTA<1:1), contrasting with the rapid oxidation of Fe(II) by O2 and H2O2 at neutral pH under the same conditions. However, partial oxidation of As(III) was observed at a 2:1 ratio of Fe(II):EDTA. Rapid Fe(II) oxidation in the presence of organic ligands did not necessarily result in the coupled As(III) oxidation. Organic ligands act as both iron speciation regulators and radicals scavengers. Further quenching experiments suggested both hydroxyl radicals and high-valent Fe species contributed to As(III) oxidation. The present findings are significant for the better understanding of aquatic redox chemistry of iron and arsenic in the environment and for optimization of iron-catalyzed arsenic remediation technology.

Characterization of Arsenic Contamination on Rust from Ton Containers

The speciation and spatial distribution of arsenic on rusted steel surfaces affect both measurement and removal approaches. The chemistry of arsenic residing in the rust of ton containers that held the chemical warfare agents bis(2-chloroethyl)sulfide (sulfur mustard) and 2-chlorovinyldichloroarsine (Lewisite) is of particular interest, because while the agents have been decontaminated, residual arsenic could pose a health or environmental risk. The chemistry and distribution of arsenic in rust samples were probed using imaging secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX). Arsenic in the III and or V oxidation state is homogeneously distributed at the very topmost layer of the rust samples and is intimately associated with iron. Sputter depth profiling followed by SIMS and XPS shows As at a depth of several nanometers, in some cases in a reduced form. The SEM/EDX ...

Nitrogen, phosphorus, arsenic, antimony, and bismuth

This chapter reviews the literature reported during 2012 on the chemistry of nitrogen, phosphorus, arsenic, antimony, and bismuth.