Bayer process during the production of alumina Inorganic Amendments for the Remediation of Cadmium-Contaminated Soils

Red Mud

Red mud is a product of the Bayer process during the production of alumina (Hairi et al., 2015). As the temperature and pressure increases, the solubility of red mud decreases with sodium hydroxide (Nie et al., 2016). Its composition depends upon its parent material from which it is produced (Liu and Wu, 2012). It is present in the form of slurry having 10–30% solid materials (Milačič et al., 2012). Its pH ranging from 10.67 measured by Italian standard soil analysis 1:2.5 ratio and also has greater ionic strength (Hua et al., 2017).

Chemical analysis revealed that it contains silica, iron, calcium, titanium, and aluminum, and has minimal concentrations of elements such as sodium, potassium, chromium, nickel, zinc, copper, etc. Moreover, its chemical composition is given as follows:

Red mud is composed of minerals such as hematite, gibbsite, calcite, quartz, goethite, diaspore, rutile, kaolinite, etc. (Wang and Liu, 2012) measured using an X-ray diffractometer. The specific weight of red mud is 2.77 gcm – 3 measured by a gas pycnometer. According to the particle size distribution, it is a very fine material and has a high surface area (Wang and Liu, 2012).

Red mud has a greater sorption capacity than any other inorganic addition because it has a large amount of hydroxides that are used in the adsorption and precipitation mechanism to remove Cd from water, and it has a large amount of Al and Fe oxides (Wang et al., 2008a). At low pH, red mud works well in removing Cd from the soil (Liu et al., 2011). Cd is more available at low pH; red mud raises the pH and stabilizes the pH due to this Cd adsorption, which increases and decreases the bioavailability of Cd (Worden et al., 2009). The use of red mud to decontaminate Cd is therefore an effective and environmentally friendly technique (Panda et al., 2017).

Anthropogenic Impacts

Though a colossal amount of red mud was discarded into the GOC for over half a century, effects on local marine food webs are unknown. 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). Because red mud is a valuable resource that can be reused (e.g. Paramguru et al., 2005; Pontikes and Angelopoulos, 2013), systematic dumping of millions of tonnes at sea, let alone within a semienclosed Gulf such as the GOC, is not only hazardous but also wasteful.

High levels of metals were found in seagrass (Posidonia oceanica) from the Bay of Antikyra (Malea et al., 1994), an area where levels of polycyclic aromatic hydrocarbons in sediments, and concentrations of polychlorinated biphenyls (PCBs) and dichlorodiphenyl trichloroethane and its metabolites (DDTs) in Mediterranean mussels (Mytilus galloprovincialis) were among the highest sampled throughout Greece (Botsou and Hatzianestis, 2012; Tsangaris et al., 2010, 2011). In the present study, distribution modelling showed no strong correlation between red mud deposits and dolphin occurrence.

Because striped dolphins tend to be epi- and mesopelagic feeders and red mud dumping impacts predominantly the seafloor, avoidance would not be expected. However, indirect effects such as contamination up the food web are possible (Jepson et al., 2016). Bottlenose dolphins are primarily benthic feeders, and thus any use of the area is likely to result in direct and indirect exposure to toxic contaminants, with unknown health effects.

Cadmium iodide
GRM1354-100G	EWC Diagnostics	1 unit	EUR 51.11
Description: Cadmium iodide

Cadmium iodide
GRM1354-500G	EWC Diagnostics	1 unit	EUR 229.86
Description: Cadmium iodide

Cadmium cyanide
C00190	Pfaltz & Bauer	1G	EUR 166.41
Description: CAS N° 542-83-6

Cadmium formate
C00330	Pfaltz & Bauer	25G	EUR 102.3
Description: CAS N° 4464-23-7

Cadmium sulfide
C00600	Pfaltz & Bauer	100G	EUR 209.84
Description: CAS N° 1306-23-6

Cadmium Chloride
06613-42	NACALAI TESQUE	25G	EUR 14

Cadmium Chloride
06613-71	NACALAI TESQUE	1G	EUR 9.8

Cadmium chromate
C00180	Pfaltz & Bauer	100G	EUR 265.69
Description: CAS N° 14312-00-6

Cadmium fluoride
C00305	Pfaltz & Bauer	25G	EUR 129.66
Description: CAS N° 7790-79-6

Cadmium Selenide
C00550	Pfaltz & Bauer	10G	EUR 126.03
Description: CAS N° 1306-24-7

Cadmium selenite
C00560	Pfaltz & Bauer	5G	EUR 123.21
Description: CAS N° 13814-59-0

Cadmium Chloride
C059000	Toronto Research Chemicals	5g	EUR 64

Description: 10108-64-2

Cadmium Sulphate
C059020	Toronto Research Chemicals	5g	EUR 58

Description: 10124-36-4

Cadmium sulphide
GRM4104-25G	EWC Diagnostics	1 unit	EUR 142.05
Description: Cadmium sulphide

Cadmium sebacate
T30683-10mg	TargetMol Chemicals	10mg	Ask for price

Description: Cadmium sebacate

Cadmium sebacate
T30683-1g	TargetMol Chemicals	1g	Ask for price

Description: Cadmium sebacate

Cadmium sebacate
T30683-1mg	TargetMol Chemicals	1mg	Ask for price

Description: Cadmium sebacate

Cadmium sebacate
T30683-50mg	TargetMol Chemicals	50mg	Ask for price

Description: Cadmium sebacate

Cadmium sebacate
T30683-5mg	TargetMol Chemicals	5mg	Ask for price

Description: Cadmium sebacate

Cadmium Molybdate
C00430	Pfaltz & Bauer	100G	EUR 217.39
Description: CAS N° 13972-68-4

Cadmium Phthalate
C00510	Pfaltz & Bauer	1G	EUR 238.82
Description: CAS N° 5064-27-7

Cadmium telluride
C00620	Pfaltz & Bauer	10G	EUR 139.27
Description: CAS N° 1306-25-8

Cadmium Tungstate
C00640	Pfaltz & Bauer	5G	EUR 169.39
Description: CAS N° 7790-85-4

Cadmium Zirconate
C00650	Pfaltz & Bauer	100G	EUR 183.88
Description: CAS N° 12139-23-0

Cadmium carbonate
GRM365-500G	EWC Diagnostics	1 unit	EUR 39.95
Description: Cadmium carbonate

Cadmium telluride
GRM4674-10G	EWC Diagnostics	1 unit	EUR 271.42
Description: Cadmium telluride

CADMIUM ELECTRODE
ISE22B	Consort	ea	EUR 520

Cadmium perchlorate
C00500	Pfaltz & Bauer	25G	EUR 57.3
Description: CAS N° 10326-28-0

Cadmium Metasilicate
C00420	Pfaltz & Bauer	10G	EUR 202.37
Description: CAS N° 13477-19-5

Cadmium Bar, 99.999%
GX4807	Glentham Life Sciences	250g	EUR 411.5

Cadmium Bar, 99.999%
GX4807-250	Glentham Life Sciences	250	EUR 361.7

Cadmium borotungstate
C00120	Pfaltz & Bauer	5G	EUR 200.78
Description: CAS N° 1306-26-9

Cadmium Monocarbonate
C595033	Toronto Research Chemicals	10g	EUR 58

Description: 513-78-0

Cadmium rods 99.99%
C00071	Pfaltz & Bauer	100G	EUR 584
Description: CAS N° 7440-43-9

Cadmium Shot 99.999%
C00072	Pfaltz & Bauer	50G	EUR 149.56
Description: CAS N° 7440-43-9

Cadmium Stannate_x000D__x000D_
C00570	Pfaltz & Bauer	100G	EUR 608.66
Description: CAS N° 12185-56-7

cadmium orthophosphate
20-abx186402	Abbexa	Ask for price Ask for price	5 g 25 g

Cadmium oxide, 99.999%
GX5303	Glentham Life Sciences	25g	EUR 565.75

Cadmium oxide, 99.999%
GX5303-100	Glentham Life Sciences	100	EUR 449.7

Cadmium oxide, 99.999%
GX5303-25	Glentham Life Sciences	25	EUR 182.5

Cadmium oxide, 99.9%
GX6089	Glentham Life Sciences	100g	EUR 111.35

Cadmium oxide, 99.9%
GX6089-100	Glentham Life Sciences	100	EUR 113.1

Cadmium Acetylacetonate
C00090	Pfaltz & Bauer	50G	EUR 316.6
Description: CAS N° 14689-45-3

Cadmium carbonate_x000D__x000D_
C00150	Pfaltz & Bauer	25G	EUR 165.9
Description: CAS N° 513-78-0

Cadmium iodide 99%
C00380	Pfaltz & Bauer	25G	EUR 79.64
Description: CAS N° 7790-80-9

Cadmium iodide, 99%
GX5272	Glentham Life Sciences	250g	EUR 444.37

Cadmium iodide, 99%
GX5272-250	Glentham Life Sciences	250	EUR 387.8

Cadmium acetate 97%
C00080	Pfaltz & Bauer	100G	EUR 225.2
Description: CAS N° 1403722

Cadmium oxalate 98%
C00480	Pfaltz & Bauer	100G	EUR 784
Description: CAS N° 814-88-0