Nickel

1. Basic Information

2. Physical and Chemical Properties

Nickel is a silvery-white metal that is hard, malleable, and ductile. It has a melting point of 1453°C and a boiling point of 2913°C. Nickel is resistant to corrosion and is often used in alloys to improve corrosion resistance. In its compounds, nickel typically has an oxidation state of +2, although it can also form compounds with oxidation states of +1 and +3. Nickel dissolves slowly in dilute acids and becomes passive when treated with nitric acid.

3. Presence in Water and Health Effects

Nickel can enter water sources through natural weathering of rocks and soil, as well as from industrial activities such as mining, smelting, and electroplating. The concentration of nickel in drinking water is usually less than 10 µg/L. Long-term exposure to nickel in drinking water can cause health effects such as contact dermatitis, kidney damage, and increased risk of lung, nose and larynx cancer. The World Health Organization (WHO) sets the maximum limit for nickel in drinking water at 70 µg/L.

4. Water Treatment Applications and Removal Methods

Some methods used to remove nickel from water include:

• Ion exchange: Cation exchange resins can be used to remove Ni²⁺ ions from water. Special chelating resins such as AmberSep™ M4195 and AmberSep™ M4196 are particularly effective for removing nickel from acidic solutions.
• Reverse osmosis: RO systems can remove up to 97% of nickel from water.
• Chemical precipitation: The addition of bases such as lime or soda ash can precipitate nickel as hydroxide.
• Adsorption: Adsorption media such as activated carbon or zeolite can remove nickel from water.
• Membrane filtration: Nanofiltration and ultrafiltration can be effective in removing nickel.

5. Industrial Uses in Water Treatment

Nickel has several applications in the water treatment industry, although not as many as other metals:

• Catalysts: Some nickel-based catalysts are used in advanced water treatment processes such as catalytic oxidation.
• Corrosion-resistant alloys: Water treatment equipment such as pumps and pipes often use nickel-containing alloys for corrosion resistance.
• Electrodes: Nickel electrodes are sometimes used in water treatment electrochemical processes.

6. Case Study and Real World Application

An electroplating factory in West Java faced the problem of high nickel content in its wastewater. They implemented a multi-stage treatment system consisting of:

1. pH adjustment to precipitate most of the nickel as hydroxide
2. Filtration to remove sediment
3. Ion exchange using specialized chelating resins to remove residual dissolved nickel
4. Reverse osmosis as the final purification stage

The system successfully reduced the nickel concentration in the effluent from an average of 50 mg/L to less than 0.1 mg/L, meeting the set discharge standard.

7. Regulatory Guidelines and Standards

In Indonesia, the Minister of Health Regulation No. 492/MENKES/PER/IV/2010 on Drinking Water Quality Requirements sets the maximum limit of nickel in drinking water at 0.07 mg/L. For industrial wastewater, the maximum limit of nickel varies depending on the type of industry, but generally ranges from 0.1-1.0 mg/L.

Internationally, the WHO guideline for nickel in drinking water is 70 µg/L. The US EPA sets the maximum allowable contaminant level for nickel in public drinking water at 0.1 mg/L.

8. Environmental Impacts and Sustainability Considerations

Nickel can accumulate in sediments and aquatic organisms, causing toxic effects on aquatic ecosystems. Nickel removal from wastewater before discharge into the environment is essential to protect aquatic habitats. Treatment methods such as ion exchange enable nickel recovery and recycling, supporting a circular economy and reducing the environmental impact of new nickel mining.

9. Future Trends and Research

Some research and development areas related to nickel in water treatment include:

• Development of new nanomaterial-based adsorbents for more efficient nickel removal
• Optimization of biosorption processes using microorganisms or plant biomass for nickel removal
• Integration of advanced membrane technology with electrochemical processes for nickel-containing water treatment
• Utilization of artificial intelligence and machine learning for real-time optimization of nickel treatment systems
• Development of in-situ sensors for continuous monitoring of nickel in water treatment systems

10. Interesting Facts Related to Water Treatment

• Although generally considered a contaminant, small amounts of nickel are actually essential for some microorganisms used in biological wastewater treatment.
• Some aquatic plants such as water hyacinth have hyperaccumulator abilities for nickel, making them potential for phytoremediation of nickel-polluted water.
• The nickel electroplating process itself is often used to coat water treatment system components to improve corrosion resistance.
• In some cases, nickel can form complexes with organic matter in water, making it more difficult to remove by conventional methods.
• The use of strong magnets has been investigated as an alternative method for removing nickel particles from water, utilizing the ferromagnetic properties of nickel.