Arsenic in Santa Catarina soils

Arsenic (As) is one of the most harmful chemical elements known to man and to the environment, mainly due its high toxicity and wide distribution; the content of this element within the soils is a genuine concern, thus making it paramount to know its natural contents in a regional context. The present study aimed to determine the natural Arsenic content in the A horizon of 31 soil profiles from the state of Santa Catarina, Brazil, which is useful in determining reference values, monitoring, remediation of contaminated areas, legal regulation and Brazilian laws. Soil samples were prepared following the USPEA 3051A SW-846 method and were previously chemically reduced from As(V) to AS(III) by using the BCR method. The determination was performed in an Inductively Coupled Plasma - Optical Emission Spectrometry - Hydride Generation (ICP-OES-HG at cold vapor). Results obtained from the soil groups reveal the materials of basaltic origins as the ones with more As content while those of sediment origins had lesser content. Evaluated soil profiles fit into the following descending order regarding their As content: Latossolos, according to EMBRAPA (Oxisols according to Soil Taxonomy) > Nitossolo (Ultisols, Oxisols (Kandic), Alfisols) > Chernossolos (---) = Cambissolo (Inceptisols) = Argissolo (Ultisols) > Neossolos (Entisols). Keywords: arsenic content, reference value, soils, trace element.

Methods of Synthesis of Oxides of Iron and Removing Compounds Arsenic in Water

Environmental pollution by heavy metals has been extensively researched using different materials and techniques but, this problem has not been fully resolved. High adsorption capacity of iron oxides such as hematite, magnetite, goethite and, ferrihydrite to remove arsenic are described in this review. There are many international investigations about the minerals of iron oxides and they describe the composition, properties, synthesis methods and involved variables. Active carbon, silicones and polymers had been used to obtain composites with iron oxides and they have gave better results to remove different anions and cations. The aim in this paper is to introduce studies already carried out and encourage research in this topic to take advantage of the particular characteristics of iron oxides and use them in the environmental remediation. In addition, it is important to introduce the natural iron oxides availability that have a lot of field to study. The literature search on the subject was carried out in Science Direct and high impact articles related to natural or synthetic oxides were used. Keywords: Arsenic, hematite, magnetite, goethite, iron composites. Resumen La contaminación ambiental por metales se ha estudiado mucho con diferentes materiales y técnicas, pero aún no se ha logrado resolver por completo este problema. La alta capacidad de adsorción de los óxidos de hierro como la hematita, magnetita, goetita, ferrihidrita, para la remoción de arsénico en agua son descritos en este trabajo de revisión. Existen muchas investigaciones internacionales de los óxidos de hierro en las que se expone la composición de estos minerales, las propiedades, métodos de síntesis y las variables que intervienen. El carbón activo, las siliconas y los polímeros son materiales que se han usado para formar compositos con estos óxidos que han contribuido a obtener mejores resultados en la remoción de diferentes aniones y cationes. Con este trabajo se pretende difundir estudios ya realizados e incentivar la investigación en este campo para aprovechar las características particulares de los óxidos de hierro y usarlos como remediadores ambientales. Ademas, es importante dar a conocer la existencia de óxidos de hierro naturales que dejan mucho campo por estudiar.

Arsenic contamination in India: Causes, effects and treatment methods

Herein the present study focuses on arsenic (As) contamination in groundwater, which plagues a vast section of the population of the world. Even the conservative estimates by the World Health Organization (WHO) estimate the number of people plagued by arsenic contaminated drinking water to be around 140-200 million. The Ganga- Brahmaputra fluvial plains in India and Padma-Meghna fluvial plains in Bangladesh are said to be one of the worst groundwater calamities to the humans. The Arsenic levels in drinking water in some of the most populated states in India are disproportionately higher than those defined by WHO guidelines. The paper, thus, delves into the anomaly in permissible limits defined by WHO and regional governments and its consequential effects. It briefly analyses the major sources of Arsenic contamination and its health effects in India. The study also looks closely into the states and districts plagued by the As contamination and explores the prominent treatment methods employed in as removal from the drinking water. Keywords: Arsenic, Adsorption, Geogenic, Arsenopyrite, Oxidation treatment

Analisis Kadar Arsen (As) pada Sayur Kubis Hijau (Brassica oleracea L.) Pasca Erupsi Gunung Sinabung

ount Sinabung has had an impact on the lives of surrounding farmers after the eruption. One of the negative impacts is the exposure of plants and animals around them to dangerous chemical compounds, especially heavy metals. This work aimed to analyze the levels of arsenic (As) in green cabbage (Brassica oleracea L.) which was exposed after two months of the eruption. The sampling method was done using a simple random sampling technique at five points. The digestion process was carried out using hydrochloric acid and nitric acid. Arsenic analysis was performed using the atomic absorption spectroscopy (AAS) at 193.7 nm with vapor hydride generation accessories. Concentration of arsenic exposed to green cabbage at five sampling points was 0.4102, 0.4936, 0.4501, 0.6425, and 0.6534 mg/Kg. The results obtained were lower than the maximum limit of arsenic contamination in vegetables, namely 1.0 mg/Kg based on SNI No. 7387:2009.Keywords: arsenic, Brassica oleracea L, AAS, SNI, Mount SinabungGunung Sinabung memiliki pengaruh kepada kehidupan petani di sekitarnya pasca erupsi. Salah satu dampak negatifnya adalah terpaparnya tumbuhan dan hewan di sekitar terhadap senyawa kimia yang berbahaya, khususnya logam berat. Penelitian ini bertujuan untuk menganalisis kadar arsen (As) yang terdapat pada sayur kubis hijau (Brassica oleracea L.) yang terpapar setelah dua bulan erupsi. Pengambilan sampel dilakukan dengan menggunakan teknik simple random sampling di lima titik. Proses destruksi dilakukan dengan menggunakan asam klorida dan asam nitrat. Analisis arsen dilakukan dengan menggunakan atomic absorption spectroscopy (AAS) pada panjang gelombang 193,7 nm yang dilengkapi vapour hydride generation accessories. Kadar arsen yang terpapar pada sayur kubis hijau pada lima titik pengambilan sampel berturut turut sebesar 0,4102; 0,4936; 0,4501; 0,6425, dan 0,6534 mg/Kg. Kadar arsen yang diperoleh lebih rendah dari batas maksimum cemaran arsen dalam sayuran yakni 1,0 mg/Kg berdasarkan SNI No. 7387:2009.Kata kunci: arsen, Brassica oleracea L., AAS, SNI, Gunung Sinabung

Arsenic in Chemical and Metallurgical Conversions of Copper-zinc Concentrates

Due to the deterioration of the quality of obtained sulfide-copper concentrates, arsenic circulates and accumulates in the intermediate products, which reduces the quality of the metal and associated product – sulfuric acid. A method of estimation the distribution of impurity elements can be created using the recycling of sulfide concentrates by various technologies (including autogenous smelting, matte conversion and flotation of slags). This technique is based on solving balance equations for iron, copper and arsenic with known compositions of the resulting products. The obtained data were used to assess of the extraction of arsenic into produce outputs (slag, matte, dust, etc.). In this study, the concentration of arsenic in the dust of metallurgical processes and sludge for cleaning acid solutions is confirmed. The increased temperature in the electrostatic precipitator of gas purification of autogenous processes lead to a partial transition of arsenic into the gas stream directed to the sulfuric acid production. It is possible to regulate the fraction of transition of arsenic to dust and sulfuric acid while changing the operating temperature in the electrostatic precipitator. To a lesser extent arsenic is concentrated in the tails of flotation of slag (11.7%) and metallic copper (2.9%). These data are useful for substantiating measures for the wastes recycling and improvement of the ecological environment in the enterprise operating districts. Keywords: arsenic, autogenous melting, matte conversion, slag flotation, purified gas treatment, distribution, dust, sludge

Arsenic Adsorption by Some Iron Oxide Minerals: Influence of Interfacial Chemistry

The dramatic increase in hydrometallurgical extraction of gold from arsenic bearing gold ores has inevitably resulted in the release of arsenic into the environment worldwide. Residual arsenic minerals in tailings storage facilities can be oxidised and mobilise arsenic into the environment. This can contaminate soils, ground and surface waters and eventually biota. In spite of well-established technologies and recent advances in arsenic remediation, there are limited knowledge and understanding of the iron oxide substrate (goethite, hematite and magnetite) mineralogy and the fate of arsenic on the surface charge of these iron oxide substrates in an aqueous media during adsorption. The aim of the present study was to investigate the influence of interfacial chemistry on arsenic adsorption onto selected iron oxide particles to assist in developing a better understanding and new knowledge in arsenic removal from contaminated waters. Bulk mineralogy and partial chemical composition of selected iron oxide minerals were obtained using quantitative x-ray diffractometry (QXRD) and acid digestion followed by metal determination using inductively coupled plasma optical emission spectrometry (ICP-OES) respectively. Zeta Potential measurements involving iron oxide particles as arsenic adsorbents were carried out to elucidate the influence of interfacial chemistry on the adsorption behavior of arsenic from solution. The study confirmed that the iron oxide minerals were predominantly hematite, magnetite and goethite with goethite containing significant amounts of quartz. Arsenic adsorption was pH dependent and strongly influenced the zeta potential and isoelectric point (IEP) of the iron oxide particles. The zeta potential of all substrates studied was strongly positive at pH 2 but indicated a reversal at pH ~ > 9. The interaction between substrates, arsenic and its hydrolysable products resulted in significant decrease in the magnitude of zeta potential and change in IEP indicating specific adsorption. Keywords: Arsenic, Adsorption, Iron Oxide Minerals, Zeta Potential

Development of Technology of Arsenic Removal from Acidic Waste Solutions in the Form of Arsenic Trisulfide

During the laboratory tests the conditions of arsenic removal from acidic waste solutions of metallurgical enterprise in the form of arsenic trisulfide were determined. The technology based on the reduction of pentavalent arsenic to trivalent state with sodium pyrosulfite solution and following arsenic trisulfide precipitation from acidic solution after treatment with sodium sulfide solution was proposed. The arsenic removal proceeds with mechanical stirring, dosing the calculated amounts of reagents and collecting emissions of hydrogen sulfide. With such treatment, about 95% of arsenic, which was in the initial solution, passes into the precipitate. An enlarged laboratory experiment was carried out and the precipitate with 42.6% of arsenic and 46.9% of sulfur was obtained. The precipitate yield was ∼25.7 kg (dry weight) out of 1 m3 of the initial arsenic containing solution. Keywords: arsenic, arsenic trisulfide, acidic waste solutions, sodium sulfide, sodium pyrosulfite

First step concerning improvement of arsenic removal by adapted Kanchan filters in the lowlands of Nepal

In the Terai region of Nepal (the southern lowlands of the country) the arsenic concentration of extracted ground water used as drinking water frequently exceeds the actual World Health Organization (WHO) drinking water guideline concentration of 10 μg/L. Single household filters (so called Kanchan filters) are employed to eliminate as from the well water. Being assembled to remove as utilizing zero-valent (ZVI) media, their efficiency was observed to vary to a high degree depending on design, ground water composition and the current operating conditions. Based on these concerns three field campaigns were organized in order to test ground water composition and filter handling on spot. This report depicts for the first time the results of this screening regarding removal efficiencies and clearly disclose future adaptation of the design and enhancement of the Kanchan filters uniquely used in Nepal. Removal efficiency varied between 5.81 % to 97.1 % depending on material, usage and mode of operation. The measurements of improvement include the replacement of nails and sand regularly; increasing the contact time between ground water and nails; preventing the nails from drying in order to maintain oxidizing settings; proper and regularly repeated instructions of the users. Keywords: Arsenic; Kanchan filters; Removal efficiency

Application of Monoclinic Bismuth Vanadate in Photooxidation of Arsenic-Polluted Water

HighlightsPhotooxidation of trivalent arsenic to pentavalent arsenic was catalyzed by s-m BiVO4 under visible light irradiation.The roles of catalyst, light, and oxygen were investigated.The photooxidation mechanism was studied, and a possible reaction route is proposed.Abstract. Oxidation is a necessary step for inorganic arsenic removal. In this study, monoclinic bismuth vanadate (BiVO4) was synthesized to photooxidize trivalent arsenic to pentavalent arsenic in water in the presence of light and oxygen. Light irradiation initiates photooxidation after physical absorption of arsenite on BiVO4. Addition of oxygen slightly improved the photooxidation efficiency. Photooxidation parameters were optimized; 2.6 mM of BiVO4 synthesized at pH 2 was effective to photooxidize 0.1 M of arsenite in alkaline solution, and 99.8% removal of trivalent arsenic was achieved with a photooxidation efficiency of 85.5%. Photooxidation by BiVO4 might be initiated by hydroxyl radicals resulting from irradiation by visible light. Appropriate BiVO4 morphology and alkalinity of the reaction mixture facilitated photooxidation. Keywords: Arsenic, BiVO4, Photooxidation, Speciation.

The Use of Bauxite as an Arsenic Filter

Arsenic (As) has the potential to negatively affect soils and groundwater quality, and cause several public health challenges. It is usually concentrated and released during metal mining of ores that contains arsenic-bearing minerals. Remediation strategies are in place to avoid pollution. In this study, bauxite from Awaso, Ghana, was characterised, and its ability to sequester As was tested under varying conditions of temperature, Eh and pH. The study showed that the best particle size in the range utilised was 80% passing 2 mm as it allowed easy percolation, and As removal was about 95%. The reaction is a favourable pseudo-second order reaction that is spontaneous and thermodynamically stable and compares well with the Langmuir Sorption Isotherm. About 80% sorption was achieved within 20 minutes of contact with low desorption rate of less than 1.8%. The study thus concludes that bauxite is a good filter for arsenic. Keywords: Arsenic, Bauxite, Filter, Sorption, Isotherm