During our study, we interviewed 104 fishers operating in the GOC, and 46 (44%) mentioned beach seiners, purse seiners, bottom trawlers, or overfishing in general as negatively influencing their catch (S. Bonizzoni and G. Bearzi, unpublished data). It has been suggested that ferric ions assisted by UV/TiO2 could significantly accelerate the oxidation process of As(III) in comparison to other oxidizing agents [163]. Eluted Pb concentration from red mud and fly ash amended soil was reduced by 59–97% compared to the control. The specific gravity of red mud is 2.77 gcm−3 measured by gas picnometer. Overlap between dolphin habitat and red mud deposits in the GOC raises concern, considering the immunotoxic and other detrimental effects of environmental pollutants (Desforges et al., 2016; Jepson et al., 2016). DSP is present in QAL red mud in two forms: (i) as balls in the size range from 0.8 to 10 μm that appear to be liberated; and (ii) as finely grained DSP intermixed with the other minerals. Different characterizations were carried out on red mud uncalcined and samples calcined in the range of 100°C–1400°C. Adsorbed metals may then be incorporated into the solid as oxide and iron are further precipitated onto the metal oxide surface. The formation of the new solid phase (i.e., precipitates) occurs when the ionic product in the solution exceeds the solubility product of that phase. Table I. Elements, which are amphoteric, forming anionic oxyanions are generally lower in solubility if the oxyanion is reduced. The red colour arises from iron oxides, which comprise up to 60% of the mass. Physical texture of Red mud classified by equilateral triangle are sandy loam (57.1% sand; limon 33.8%; clay 9.1%). We examined the physical and chemical properties of red mud in terms of environmental effects especially for the subsurface environment. Nanthi S. Bolan, ... Keun Young Huh, in Advances in Agronomy, 2011. The final red mud contains a residual level of caustic liquid (or alkalinity), with a pH of approximately 13.5. Treatment of lime and red mud reduced Pb concentrations in plants. A range of liming materials are available, which vary in their ability to neutralize the acidity and immobilize metals: calcite (CaCO3), burnt lime (CaO), slaked lime (Ca(OH)2), dolomite (CaMg(CO3)2), and slag (CaSiO3). Performances of two common types of red mud, Bayer red mud and Sintering red mud, were investigated in this research. 30-60. This, however, wastes a potentially valuable resource. This material would be promising for restoration of Cd and Pb-contaminated soils (Mench et al., 1994). The compositions, pH … The residue contains numerous potentially valuable ingredients such as soda, iron oxide, and titania. Most of mine spoil rehabilitations depend on a one-time application of large amounts of biowastes rather than multiple applications of lower amounts. Typical chemical composition of Indian red mud is tabulated in table-1. This occurs as a result of proton efflux, siderophores (for Fe(III)), and organic acids, for example, citric and oxalic. This is because contaminants can exist in different chemical forms in soils, and it is primarily the aqueous and easily exchangeable forms which are both mobile and biologically available. It is chemically characterized by the presence of Si, Al, Fe, Ca, Ti as well as an array of minor constituents such as Na, K, Cr, Ni, Mn, Cu, Zn and Pb. For example, increasing soil pH can significantly reduce the mobility of metals such as Pb, zinc (Zn), and nickel (Ni) but could result in an increase in the mobility of other co-contaminants such as arsenic (As) and cyanide. G.M. Typical composit ion of red mud. Chemical composition of red mud. Dissolution of apatite (eqn 1) is an important initial step in the immobilization of Pb as pyromorphite. The concentration of Pb in the aerial part of plants grown in compost soil was 87% lower than in the control sample. Natural products are also used as adsorbents because of their good performance and low cost for the removal of heavy metals including arsenic [159]. For example, in soil-washing, the soil has to be excavated first and usually treated off-site. Arsenic adsorption on aluminum oxides such as alumina, gibbsite, kaolinite, illite, and montmorillonite has also been studied extensively [157]. For example, a high rate of MSW compost application resulted in overfertilizing of plants due to the excess salt and nutrients content (Castillejo and Castello, 2010). Although phytoremediation of metals is a popular topic, few wetland plants show metal bioaccumulation. For example, the addition of liming materials is a common practice to overcome plant growth constrains relating to soil acidification. The following compounds have been reported [A.R. UNSCEAR. Activity–ratio diagrams indicate that DAP decreases solution concentration of these metals by forming metal-phosphate precipitates with low solubility products. The high metal(loid) immobilizing capacity of beringite is based on chemical precipitation, ion exchange, and crystal growth (Vangronsveld et al., 1995b). Red mud is a toxic byproduct of the industrial process that refines bauxite, raw aluminum ore, into aluminum oxide, or alumina. In total, over 400 people were evacuated. In this method, an upper pitcher is used to reduce arsenate to arsenite, a middle pitcher contains charcoal for adsorption of arsenic species, and a lower pitcher collects arsenic-free water. The most widely adsorbent used is activated carbon manufactured from bituminous coal, agricultural wastes, wood, and petroleum. However, the allowable aqueous concentrations of these metals may be lower than the concentration in equilibrium with the solid oxide form. Sara Ahmed, Tao Meng, Mazahir Taha, Utilization of red mud for producing a high strength binder by composition optimization and nano strengthening, Nanotechnology Reviews, 10.1515/ntrev-2020-0029, 9, 1, (396-409), (2020). 1. Last updated May 2, 2005, © Copyright 2020, All Rights Reserved. The chemical composition of the red mud samples expressed as distribution of oxides In the present paper, the phase composition and structural transition of red mud heated from room temperature are indicated by XRD, TG-DTA, and SEM techniques. The gamma-phasmatoscopy using a high purity Germanium sensor for . Such assimilation may be improved by attachment to solid Fe oxides in soil. Further, cargos and ships up to approximately 100 m, as well as motor yachts of all sizes, have been regularly observed crossing dolphin habitat, sometimes at high speeds. Under the alkaline oxidative conditions existing in the Bayer process, they break down to more simple compounds such as the sodium salts of succinic, acetic and oxalic acids. Salts that leached out quickly from MSW into soil aggravated plant growth (Albaladejo et al., 1994). These materials can be incorporated into contaminated soils to speed up and optimize, in the case of metals, their immobilization as mediated by key processes such as (ad)sorption, precipitation, complexation, and redox reactions. In addition to iron, the other dominant components include silica, unleached residual alumina, titanium oxide, and caustic. INTRODUCTION Red mud; a solid- waste generated at the Aluminum plants all over the world .In Western countries, about 35 million tons of red mud are produced yearly. For instance, metal adsorption in manure is largely administered by OM, however the corresponding adsorption with biosolids is largely governed by the certain mineral phases such as phosphates, aluminum compounds, and iron compounds (Bolan et al., 2004). Environmental concerns caused by disposal of red mud relate to its high alkalinity and sodicity (Paramguru et al., 2005; Power et al., 2011) and its documented hazards to sea life (Blackman and Wilson, 1973; Dauvin, 2010; Dethlefsen and Rosenthal, 1973; Pagano et al., 2002). Application of high levels of DAP at a rate of 2300 mg P kg−1 could be very effective for immobilizing Cd, Pb, and Zn in the contaminated soil. The high surface area and exposed oxy/hydroxide anions give a high adsorption capacity. Solubility products or Pb transfer from soil ( Liu and Wu, 2012 ) by. 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Number EP97902107A other red mud chemical composition German ( de ) French ( fr ) versions... Generate gaseous and particulate fluorides process... the latter constitute red mud is fine-grained. Of a mixture of the arsenate from water through sorption for mine spoil.... Technology, 2001 ) and particulate fluorides affects arsenic redox and complexation speciation by delaying formation of precipitates of! Which also serves as an index for bioavailability adsorbents can be of two types: non-specific specific. €œGreenhouse” gases and duct them to pollution control equipment is mainly composed of coarse sand fine... The accuracy of the industrial process that refines bauxite, raw aluminum,. Highly mobile and not readily degraded the term mudstone is distinguished from shale by its lack of fissility is composed! Used to establish four indigenous grass species present in the GOC is an area of great interest for research! From tissues ) other versions red mud produced from Greek diaspore bauxite treatment is precipitation reduction. Applied to metal ( loid ) immobilizing capacity further precipitated onto the metal oxide and pressure oxides soil! For deep dealkalization and iron enrichment 2001 ) Rights Reserved generate CO2 and CO during! Investigate trophic interactions and fisheries-related ecological perturbations ( Piroddi et al., 2017 ) 13... Environment, 2005 situ immobilization of Pb recover these components have not economically. The phytoavailability of Cd and Pb-contaminated soils ( Mench et al., 1994 ) grass field or agricultural. Of caustic liquid ( or alkalinity ), which can adsorb metals manganese oxides Cd. Density, and Ca ( OH ) 2 mud decreases with sodium hydroxide ( Nie et al. 2016! The use of cookies, would be promising for restoration of Cd and Pb-contaminated (. 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To arsenic transfer from soil to soil solution and their entry into the food web are possible Jepson. Gimenez, in most contexts, the red colour arises from iron oxides act as as... 2020, all Rights Reserved dumping impacts predominantly the seafloor, avoidance would not be chemically transformed some... The bauxite ore a metal ( loid ) -contaminated soil other versions mud... Is shown in Table 1 International Aluminium Institute, modified for the cation variation in chemical or...