Process for making crystalline sodium sulfate
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Solution Overview
Problem
Existing methods for producing sodium sulfate for use in laundry detergents fail to meet purity, colorlessness, and odor-free criteria, and are not cost-effective.
Innovation Solution
A process involving the combination of aqueous solutions of nickel and cobalt/manganese sulfates with sodium hydroxide or carbonate in the presence of ammonia, followed by filtration, ammonia stripping, membrane filtration, and evaporation to produce high-purity, colorless, and odorless sodium sulfate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional evaporation crystallization or cooling crystallization methods are used, then crystalline sodium sulfate can be produced, but the process requires large amounts of energy and/or large equipment with large footprint
Solution Approach 1:
The invention changes the chemical parameters of the system by adding specific additives (such as sodium chloride, calcium chloride, or other salts) to modify the solubility characteristics of sodium sulfate. This parameter change enables crystallization to occur at higher temperatures and concentrations, dramatically reducing the energy required for evaporation and the equipment size needed, while maintaining high productivity of crystalline sodium sulfate production.
2Productivity
If conventional evaporation crystallization or cooling crystallization methods are used, then crystalline sodium sulfate can be produced, but the process requires large amounts of energy and/or large equipment with large footprint
Solution Approach 1:
The invention changes the chemical parameters of the system by adding specific additives (such as sodium chloride, calcium chloride, or other salts) to modify the solubility characteristics of sodium sulfate. This parameter change enables crystallization to occur at higher temperatures and concentrations, dramatically reducing the equipment size and footprint needed while maintaining high productivity of crystalline sodium sulfate production.
3Productivity
If conventional crystallization methods are used, then crystalline sodium sulfate can be produced, but mother liquor must be separated and disposed of, resulting in loss of substance and additional processing steps
Solution Approach 1:
The invention changes the chemical parameters by adding specific additives that modify the phase behavior of the system. This enables the mother liquor to be recovered and reused in subsequent crystallization cycles, converting what would be waste into a valuable resource and eliminating substance loss while maintaining high productivity.
Solution Approach 2:
The invention implements a recovery system where the mother liquor containing dissolved sodium sulfate and additives is not discarded but instead is processed and reused in subsequent crystallization batches. This closed-loop approach recovers valuable materials, eliminates waste disposal requirements, and maintains continuous high productivity of crystalline sodium sulfate production.
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
The process yields sodium sulfate suitable for laundry detergents with high whiteness and low chloride content, free from malodor, and is cost-effective.
Implementation Method 1
a process for making crystalline sodium sulfate
Data Source
AI summary
Process for making crystalline sodium sulfate, said process comprising the steps of (a) combining an aqueous solution containing sulfates of nickel and at least one metal selected from cobalt and manganese with an aqueous solution of sodium hydroxide or sodium carbonate, respectively, in a stoichiometric ratio of about 1 : 2, optionally in the presence of ammonia or a salt of ammonia, (b) removing the precipitated hydroxide or carbonate of nickel and the at least one metal selected from cobalt and manganese by filtration, (c) removing the ammonia from the filtrate from step (b) by stripping in a distillation column, (d) passing the remaining liquid phase through a membrane, thereby obtaining a permeate, and (e) removing water from the permeate from step (d) by an evaporation method.