— A hydrothermal upgrading process was developed for removal of heavy metals, including arsenic, lead, zinc and copper, and upgrading bio-oil from P. vittata and a heavy metals removal efficiency of >99% and crude bio-oil upgrading efficiency of 83.76% were attained under the determined conditions. The hydrothermal upgrading bio-oil …
arsenic xide into crystalline scorodite (FeAs0 4 • 2HzO) using acidic nitrate solu tions at temperatures ranging from 140°C to 160"C. A schematic process flow sheet is proposed. The reasons for processing arsenic xide, especially baghouse dust from met allurgical operations, lie in its toxic charac
— Arsenic exposure through drinking water has established health impacts (), and although existing science supports the assumption that effects will be similar from food, the role of diet in population arsenic exposures has been less studied.Most epidemiologic studies describing arsenic's effects have relied on drinking water concentrations or urine …
— The invention claimed is: 1. An arsenic removal method, comprising: a leaching step of leaching a non-ferrous smelting intermediate comprising a copper arsenic compound in the form of an intermetallic compound in the presence of monatomic sulfur, and obtaining a leaching solution comprising arsenic; a solution adjusting step of …
— With new environmental legislation, demand arose for a simple and low-cost technology for arsenic waste processing into the disposable form. One of the cheapest methods consists of precipitation with lime. It has been proven however, that resulting solids are unstable when exposed to atmospheric carbon dioxide [1].
— This method is typically not used for residential treatment because it requires frequent adjustments to optimize the process and remove all of the arsenic. 7 – Oxidation with filtration. Oxidation with …
— The choice of a sulfuric acid or alkaline method of waste processing is defined by the technological possibilities of separating arsenic from the resulting …
— The aim of this study was to propose an intermediate processing stage (ii), between alkaline pretreatment (i) and gold leaching (iii), to remove the greatest amount …
— Soaking will be an alternative process to remove arsenic in brown rice. Abstract. One of the main food crops in the world, rice can accumulate high levels of arsenic from flooded paddy soils, which seriously threatens human health. Soaking, a common processing method for brown rice products, especially for brown rice noodles, was …
— Arsenic poisoning is a global health issue affecting millions of people worldwide through environmental and occupational exposure, as well as intentional suicide and homicide attempts. Although arsenic homicides commonly receive media publicity, the primary source of arsenic toxicity to the general population is by contaminated water, …
— Batch pressure leach test work was conducted in 4 L autoclaves. Various compositions of feed solids, including both concentrates and/or the arsenic dust described above, and quench solutions (process water and acid plant effluent) were tested over a range of operating temperatures (200–230 °C) to select the conditions for pilot plant testing.
The purpose of this briefing is to provide a general overview about the occurrences of arsenic, its economic uses, and its environmental and health impacts. ... The mining, mineral processing and metallurgical industries support and strictly follow state and federal regulations to ensure protection of the environment and the health of industry ...
As described in the following sections of this chapter, it has been possible to demonstrate that methylation of As in many species is an enzymatically catalyzed process that is consistent with Challenger's original scheme for this process. A single protein, arsenic (+3 oxidation state) methyltransferase (AS3MT), catalyzes both reduction and ...
The half-life of inorganic arsenic in humans is about 10 hours [Rossman 2007]. Arsenic undergoes biomethylation in the liver. Approximately 70% of arsenic is excreted, mainly in urine [Rossman 2007]. Arsenic is excreted in the urine; most of a single, low-level dose is excreted within a few days after ingestion.
Arsenic is a worldwide environmental pollutant and a human carcinogen. It is well recognized that the toxicity of arsenicals largely depends on the oxidoreduction states (trivalent or pentavalent) and methylation levels (monomethyl, dimethyl, and trimethyl) that are present during the process of metabolism in mammals.
WASTE MANAGEMENT Waste Management 19 (1999) 55±59 Processing of arsenic waste by precipitation and solidi®cation P. Palfy*, E. Vircikova, L. Molnar Faculty of Metallurgy, Technical University of Kosice, Kosice, Slovakia Accepted 6 January 1998 Abstract As a consequence of more stringent environmental legislation being applied in Slovakia, …
— While the exact mechanism is unclear, aberrant changes in genome and gene expression are suggested as an underlying process. Carcinogenic metals such as arsenic, cadmium, and chromium can disrupt DNA synthesis and repair (Clancy et al., 2012; Koedrith et al., 2013). The toxicity and carcinogenicity of heavy metals are dose dependent.
— Arsenic can also be methylated in the process of biological methylation, facilitated by microorganisms such as fungi, bacteria, algae, and phytoplankton. This methylation process can lead to the formation of organo-As compounds, including monomethylarsonous acid [CH 3 As (OH) 2 ], dimethylarsonous acid [(CH 3 ) 2 As (OH) …
— However, for the arsenic removal process to be considered in arsenopyrite processing, it must not negatively impact the gold recovery in the subsequent thiosulfate leaching stage. Contrary to what was achieved for arsenic, the preceding stage of arsenic dissolution with oxalic acid, significantly decreased the gold extraction, from 81% to 32% ...
— Arsenic speciation analysis on the collected samples showed that As associated with δ-MnO 2 was present as As(V) and no As(III) was observed in the effluent during the desorption phase (Lafferty et al ... Using a process-based modeling approach, this study evaluated a conceptual model that reflects the widely accepted mechanisms …
Various pyrometallurgical methods for treating copper concentrates that contain appreciable arsenic are reviewed. Various aspects of the engineering of these treatment methods are discussed. The methods discussed include: complete oxidation with arsenic fixation;...
— With new environmental legislation, demand arose for a simple and low-cost technology for arsenic waste processing into the disposable form. One of the cheapest methods consists of precipitation with lime. It has been proven however, that resulting solids are unstable when exposed to atmospheric carbon dioxide[1]. Another wide-spread and ...
— Arsenic may be present in food from the environment where foods are grown, raised, or processed. ... processing, and manufacturing foods that contain lower levels of environmental contaminants ...
— Arsenic is a naturally occurring element in the environment. Rock, soil, water, air, plants and animals all contain some level of arsenic. Arsenic combines with inorganic and organic substances to form many different compounds. Inorganic compounds. Arsenic combines with oxygen, chlorine and sulfur to create inorganic arsenic compounds.
— The presence of arsenic in water bodies depends on pH, the redox condition of the solution, sorption, and exchange reactions. The World Health Organization (WHO) has established a guideline value of a maximum of 10 μg/L for arsenic in drinking water.Historically, arsenic has been used in fertilizers and medicines, and as a wood …
This paper presents the effect of pH and redox potential on the potential mobility of arsenic (As) from a contaminated mineral processing waste. The selected waste contained about 0.47 g kg(-1) of As and 66.2 g kg(-1) of iron (Fe). The characteristic of the waste was identified by acid digestion, X- …
Arsenic is commonly found as an impurity in sulfide ores, and is produced commercially for use in pesticides, wood preservatives, metal alloys, and other technologies. It is also listed as critical mineral under Presidential executive order 13817, because it has important uses in our economy, …
— Arsenic is used industrially as an alloying agent, as well as in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives and ammunition. Arsenic is also used in the hide tanning …
Arsenic contaminations, often adversely influencing the living organisms, including plants, animals, and the microbial communities, are of grave apprehension. Many physical, chemical, and biological techniques are now being explored to minimize the adverse affects of arsenic toxicity. Bioremediation of arsenic species using arsenic loving bacteria has …
— In bacteria, the arsenic resistance system (ars) operon is located in chromosomes or plasmids. The ars genes function as detoxifiers of inorganic arsenic compounds. In the detoxification process of As(III), the extrusion of As(III) is catalyzed by the arsenite efflux permease (Ars B), which is encoded by the ars B gene of the ars …
— Table IV shows the level of development of some technology responses for processing complex arsenic-containing materials.30, 31 Most of these technologies have been developed to process high-arsenic …
— Arsenic is trapped via precipitation, adsorption, and ion exchange mechanisms. Zero-valent iron, montmorillonite, and zeolites have been used as reactive …
— 1. Introduction. Arsenopyrite, the main arsenic-containing mineral, has emerged as the major source of environmental arsenic pollution. However, despite the ubiquity of arsenopyrite and the potential environmental impact and health hazards of arsenic on the environment, limit information is available regarding the stability and …
— F.D.A. inspectors also said that the supplier, Valley Processing of Sunnyside, Wash., used rotting or moldy apples and pears, in addition to expired concentrate, to make juice.
— The oxidation process was performed by continuous EC of the applied aerobic iron because it occurs in the electrochemical reactor (see Fig. 3) and average arsenic sludge generated from the process (35.8–70.64 mL L-1 per cycle). The oxidation process represents electrochemical coagulation, and As(III) oxidizes at pH conditions of …
— The existence of arsenic in soil systems is a fate to the environment since it is mobile and being transported to other systems because of its bioavailability and …
— Mineral deposits contain arsenic, combined with sulfur and metals such as cobalt, copper, gold and iron, from which it can be recovered as arsenic xide during …
— In a previous study, the positive effect on gold extraction from arsenopyrite was shown to coincide with the release of arsenic during the two processing stages (Mesa Espitia and Lapidus, 2015). The refractory mineral studied in this research required an alkaline pretreatment with NaOH, prior to the gold leaching with sodium thiosulfate to ...
