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.

Ion Selective Electrode Std Cadmium 0.1M
ISECD01-5	Scientific Laboratory Supplies	5L	EUR 1247.16

Ion Selective Electrode Std Cadmium 1000ppm
ISECD5	Scientific Laboratory Supplies	500ML	EUR 132.24

Cadmium Chloride, 1 M, 100 ML
M-CSS-151	MiTeGen	4 x 25 ml	EUR 108

Description: Cadmium Chloride, 1 M, 100 ML

Cadmium Sulfate, 1 M, 100 ML
M-CSS-152	MiTeGen	4 x 25 ml	EUR 108

Description: Cadmium Sulfate, 1 M, 100 ML

Kinesis Hollow Cathode Lamp Cadmium 37mm Std
CHR5543	Scientific Laboratory Supplies	EACH	EUR 290.7

Kinesis Hollow Cathode Lamp Cadmium 50mm Standard
CHR5551	Scientific Laboratory Supplies	EACH	EUR 391.02

ICP Std Cadmium 10ug/mL in 2% HNO3
PCD01A6	Scientific Laboratory Supplies	100ML	EUR 78.66

ICP Std Cadmium 10ug/mL in 2% HNO3
PCD01D6	Scientific Laboratory Supplies	50ML	EUR 49.02

Icp Standard Cadmium 2-5% Hno3 1000ug/ml
PCD2A2	Scientific Laboratory Supplies	100ML	EUR 95.76

ICP Std Cadmium 1000ug/mL in 2% HCl
PCD2A3	Scientific Laboratory Supplies	100ML	EUR 95.76

ICP Std Cadmium 1000ug/mL in 2% HCl
PCD2C3	Scientific Laboratory Supplies	500ML	EUR 206.34

ICP Std Cadmium 1000ug/mL in 0.5M HNO3
PCD2C4	Scientific Laboratory Supplies	500ML	EUR 245.1

ICP Std Cadmium 10000ug/mL in 3.5% HNO3
PCD4B4-500ML	Scientific Laboratory Supplies	500ML	EUR 361.38

IC Cation Std Cadmium 1000ppm in 0.005% HNO3
ICCB09	Scientific Laboratory Supplies	500ML	EUR 327.18

IC Cation Std Cadmium 1000ppm in 0.005% HNO3
ICCS09	Scientific Laboratory Supplies	100ML	EUR 126.54

IC Cation Std Cadmium 100ppm in 0.005% HNO3
ICCU09	Scientific Laboratory Supplies	100ML	EUR 109.44

Kinesis Hollow Cathode Lamp Cadmium 37mm unicam Coded
CHR5547	Scientific Laboratory Supplies	EACH	EUR 330.6

Kinesis Hollow Cathode Lamp Cadmium 37mm Varian Coded
CHR5549	Scientific Laboratory Supplies	EACH	EUR 330.6

ICP Std Cadmium 100ug/mL in 2-5% HNO3
PCD1A2	Scientific Laboratory Supplies	100ML	EUR 166.44

ICP Std Cadmium 100ug/mL in 2-5% HNO3
PCD1C3	Scientific Laboratory Supplies	500ML	EUR 230.28

ICP Std Cadmium 1000ug/mL in 2-5% HNO3
PCD2B2	Scientific Laboratory Supplies	250ML	EUR 171

ICP Std Cadmium 1000ug/mL in 2-5% HCl
PCD2B3	Scientific Laboratory Supplies	250ML	EUR 171

ICP Std Cadmium 1000ug/mL in 2-5% HNO3
PCD2C2	Scientific Laboratory Supplies	500ML	EUR 241.68

ICP Std Cadmium 10000ug/mL in 2-5% HNO3
PCD4A2	Scientific Laboratory Supplies	100ML	EUR 167.58

ICP Std Cadmium 10000ug/mL in 2-5% HCl
PCD4B3	Scientific Laboratory Supplies	250ML	EUR 223.44

ICP Std Cadmium 10000ug/mL in 2-5% HNO3
RPCD4B2	Scientific Laboratory Supplies	250ML	EUR 285

Kinesis Hollow Cathode Lamp Cadmium 50mm PE AAnalyst (Lumina)
CHR5553	Scientific Laboratory Supplies	EACH	EUR 494.76

EP Reagent Conc to make Cadmium Std Sol. 0.1% Cd
5000700	Scientific Laboratory Supplies	100ML	EUR 213.18

Cadmium 1000 ug/g (1000 PPM) for AA and ICP 50 grams in Base Oil 75
ORG-CD8-2Z	Scientific Laboratory Supplies	50G	EUR 63.84

Cadmium 5000 ug/g (5000 PPM) for AA and ICP 50 grams in Base Oil 75
ORG-CD8-4Z	Scientific Laboratory Supplies	50G	EUR 77.52

Assurance Grade Cadmium for AA and ICP 1000 ug/mL (1000 PPM) 30mL in 2% HNO3
PLCD2-2M	Scientific Laboratory Supplies	30ML	EUR 30.78

Assurance Grade Cadmium for AA and ICP 1000 ug/mL (1000 PPM) 250mL in 2% HNO3
PLCD2-2T	Scientific Laboratory Supplies	250ML	EUR 86.64

Assurance Grade Cadmium for AA and ICP 1000 ug/mL (1000 PPM) 500mL in 2% HNO3
PLCD2-2X	Scientific Laboratory Supplies	500ML	EUR 111.72

Assurance Grade Cadmium for AA and ICP 1000 ug/mL (1000 PPM) 125mL in 2% HNO3
PLCD2-2Y01	Scientific Laboratory Supplies	125ML	EUR 55.86

Assurance Grade Cadmium for AA and ICP 10000 ug/mL (10000 PPM) 500mL in 5% HNO3
PLCD2-3X	Scientific Laboratory Supplies	500ML	EUR 192.66

Assurance Grade Cadmium for AA and ICP 10000 ug/mL (10000 PPM) 125mL in 5% HNO3
PLCD2-3Y	Scientific Laboratory Supplies	125ML	EUR 92.34

Kinesis Hollow Cathode Lamp Aluminium Cadmium Copper Iron Magnesium Silicon Zinc 50mm Standard HCL-ALCACuFEMGSIZN-50
CHR6101	Scientific Laboratory Supplies	EACH	EUR 687.42

Claritas PPT Grade Cadmium for ICP-MS 1000 ug/mL (1000 PPM) 30mL in 2% HNO3
CLCD2-2M	Scientific Laboratory Supplies	30ML	EUR 44.46

Claritas PPT Grade Cadmium for ICP-MS 1000 ug/mL (1000 PPM) 125mL in 2% HNO3
CLCD2-2Y	Scientific Laboratory Supplies	125ML	EUR 84.36