Nanofiltration Membrane Separation of Cobalt and Nickel Salts
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Solution Overview
Problem
Existing methods for recovering cobalt and nickel from aqueous solutions, such as solvent extraction and ion exchange resin, are inefficient, environmentally impactful, and require large facilities due to low selective separability and the need for significant organic solvent use.
Innovation Solution
A method using a nanofiltration membrane with specific permeability characteristics and a polyamide separation layer to selectively separate and recover cobalt and nickel salts from an aqueous solution, enhanced by a complex forming step and multiple separation stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solvent extraction method is used to recover nickel and cobalt, then recovery efficiency is improved, but environmental impact increases due to large amount of organic solvent use and facility scale increases
Solution Approach 1:
The patent replaces the chemical solvent extraction system with a membrane filtration system. The nanofiltration membrane physically separates cobalt and nickel ions from the aqueous solution through size exclusion and charge-based rejection, eliminating the need for organic solvents while maintaining high recovery efficiency
Solution Approach 2:
The patent employs a nanofiltration membrane with specific pore size and charge characteristics to selectively retain cobalt and nickel ions. The membrane's porous structure allows water and small molecules to pass through while blocking metal ions, enabling solvent-free separation and recovery
2Device complexity
If ion exchange resin method is used to recover nickel and cobalt, then recovery process is simplified, but selective separability decreases and additional solvent extraction is required
Solution Approach 1:
The patent changes the separation mechanism from chemical ion exchange to physical membrane filtration with size and charge-based selectivity. By adjusting membrane parameters (pore size, surface charge) and operating conditions (pH, pressure), the system achieves high selective separability while maintaining process simplicity
Solution Approach 2:
The nanofiltration membrane combines multiple functional characteristics (porous structure, surface charge, hydrophilicity) into a single composite material that simultaneously provides both simplification and high selective separability, eliminating the need for subsequent solvent extraction steps
3Quantity of substance
If conventional nanofiltration membrane is used, then organic solvent permeability is improved, but sucrose permeability increases and selective separability decreases
Solution Approach 1:
The patent applies local quality by creating regions of different pore sizes and charge densities within the membrane structure. The membrane has hydrophilic channels that preferentially allow water and small organic molecules to pass while maintaining charged regions that reject metal ions through electrostatic repulsion
Solution Approach 2:
The patent uses a specifically designed porous nanofiltration membrane with controlled pore size distribution and surface properties. The porous structure is optimized to allow passage of isopropyl alcohol and water while blocking cobalt and nickel ions through combined size exclusion and electrostatic repulsion mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves high selective separability and efficient recovery of cobalt and nickel without large facilities, reducing environmental impact and operational costs.
Implementation Method 1
a separation step of separating, by using a nanofiltration membrane, a cobalt salt and a nickel salt from a rare metal-containing aqueous solution
Implementation Method 2
when a 1,000 mg/L glucose aqueous solution, a 1,000 mg/L sucrose aqueous solution, and a 1,000 mg/L isopropyl alcohol aqueous solution, each having a pH of 6.5 and a temperature of 25° C., individually permeate through the nanofiltration membrane
Implementation Method 3
the nanofiltration membrane includes a base material, a support membrane on the base material, and a separation function layer on the support membrane, and the separation function layer includes a polyamide
Data Source
AI summary
A method of separating and recovering a cobalt salt and a nickel salt includes a separation step of separating, by using a nanofiltration membrane, a cobalt salt and a nickel salt from a rare metal-containing aqueous solution containing at least both the cobalt salt and the nickel salt as rare metals, in which the nanofiltration membrane has a glucose permeability of 3 times or more a sucrose permeability, the sucrose permeability of 10% or less, and an isopropyl alcohol permeability of 50% or more when a 1,000 mg/L glucose aqueous solution, a 1,000 mg/L sucrose aqueous solution, and a 1,000 mg/L isopropyl alcohol aqueous solution, each having a pH of 6.5 and a temperature of 25° C., individually permeate through the nanofiltration membrane at an operating pressure of 0.5 MPa.