Nickel is extracted from limonite, pentlandite and garnierite ores. Nickel presence on earth should have a meteoric origin, since it has little presence in the earth’s crust despite being the 23rd most abundant element of our solar system. Nickel is mainly used for stainless steel and nickel alloys production. Toxicological studies suggest nickel to be toxic for the kidneys and immune system.
Natural waters contain less than 20µg/L of nickel. However, groundwater from contaminated areas may exhibit nickel concentrations above the WHO guideline of 70 µg/l. The Pourbaix or potential/pH diagram in figure 1 of nickel show that the nickel speciation is dominated by its cationic elementary Ni2+ form.
Figure 1 The Pourbaix or potential/pH diagram of nickel species
This is the simplified Pourbaix diagram of nickel in water. Note this graph is not from Jacobi. Reproduction is possible but no disclosure as is. The area between the dotted lines represents the stability zone of water.
How is nickel removed from groundwater?
Resinex™ CH-23 exhibit a very high efficiency in lead and nickel removal in their cationic elementary form (Ni²⁺). As a magnitude of order, the average removal capacity of Resinex™ CH-23 is respectively 20g of Ni²⁺ per litre resin*. Resinex™ CH-23 is a chelating resin removes also efficiently cadmium, cobalt, copper and lead in their elementary cationic form.
Recommended nickel (Ni²⁺) removal operating conditions
One AquaFlow™ can be used for the removal of nickel (Ni²⁺) at a superficial contact time of a minimum of 6 minutes but usually two AquaFlow™ in series, merry-go-round systems are used with a typical flow rate per vessel: 10- 20 BV/h.
How to calculate nickel (Ni²⁺) removal from groundwater
Assume a contaminated groundwater with 0,3 mg/l nickel (Ni²⁺) as an average flow of 30m³/h operating 24/24 -7/7 then we have 0,3 mg/l x 30m³/h x 8600 hpa/(1000 mg/g) /(1000 g/kg) = 77kg per year. This gives at an average loading of 15kg Ni²⁺/m³ Resinex™ CH-23 a consumption of approximately 5m³ per annum. An AquaFlow™ can then be selected from our industrial mobile filter range in order to obtain the desired exchange frequency.
* It is always recommended that you contact our technical expert for sizing of a heavy metal removal system as other metals can interfere in the estimated consumption.