Dioxane Removal from Sulfated Detergent Paste
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Solution Overview
Problem
Current methods for minimizing 1,4-dioxane in sulfated detergent products, such as fatty alcohol ethoxy sulfates, are inefficient and impact production capacity and cost, as they either modify the sulfation process or rely on incomplete conversion, failing to effectively reduce 1,4-dioxane to insignificant levels.
Innovation Solution
A process involving the use of an evaporator to vaporize dioxane and water from a dioxane-containing paste, concentrating the paste, and then adjusting the pH and diluting it to achieve a high active sulfate concentration, while optionally using a stripper/dryer with channels and flow restrictions to enhance dioxane removal, achieving a dioxane reduction ratio of at least 7:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the SO3 gas concentration is reduced from 4% to 2.5% to minimize dioxane formation, then the amount of 1,4-dioxane that forms is cut in half, but the production capacity and cost-efficiency of the sulfation plant are dramatically impacted, cutting plant capacity by as much as 50%
Solution Approach 1:
The patent extracts and removes dioxane from the sulfated product through a dedicated removal process using activated carbon filtration and/or distillation, rather than trying to prevent its formation during sulfation. This allows the sulfation process to operate at optimal SO3 concentrations for production efficiency while separately addressing dioxane removal.
Solution Approach 2:
The patent applies preliminary actions by implementing dioxane removal steps (activated carbon treatment and/or distillation) after sulfation but before final product formulation. This sequential approach allows efficient sulfation followed by targeted dioxane elimination, resolving the contradiction between production capacity and dioxane minimization.
2Object-affected harmful factors
If the mole ratio of SO3 to feed is reduced to minimize dioxane formation through incomplete conversion, then dioxane levels are reduced, but the conversion of feed to sulfated product is less complete, impacting production efficiency
Solution Approach 1:
The patent extracts dioxane from the product mixture using activated carbon filtration and/or distillation, allowing the sulfation reaction to proceed to high conversion levels without being constrained by dioxane formation concerns. The extraction step selectively removes dioxane regardless of conversion completeness.
Solution Approach 2:
The patent implements dioxane removal as a preliminary or subsequent step separate from the sulfation conversion process, enabling independent optimization of both conversion completeness and dioxane levels without compromising either parameter.
3Object-affected harmful factors
If conventional evaporation methods are used to remove dioxane, then some dioxane is removed, but the process is inefficient and cannot achieve insignificant dioxane levels without impacting production capacity
Solution Approach 1:
The patent introduces activated carbon as an intermediary substance that selectively adsorbs dioxane from the sulfated product. This intermediary mechanism enables efficient dioxane removal without requiring extensive process modifications that would impact production capacity.
Solution Approach 2:
The patent employs distillation to change the physical state and separation parameters of dioxane from the product mixture, enabling efficient separation based on volatility differences. This parameter-based separation achieves significant dioxane removal while maintaining production efficiency.
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 process effectively reduces 1,4-dioxane to less than 20 ppm in the final product, increasing the active sulfonate content and improving the handling and efficiency of detergent paste production, while maintaining product quality and safety.
Implementation Method 1
supplying heat to the paste in the evaporator, and reducing the vapor pressure in the evaporator, to vaporize dioxane and water from the paste
Implementation Method 2
reducing the vapor pressure in the evaporator, to vaporize dioxane and water from the paste
Implementation Method 3
selectively applying pressure to the paste to avoid vaporization of water; introducing the paste into the channel; supplying heat to the paste in the channel and selectively reducing the pressure along the channel resulting in the flashing of dioxane and water components
Data Source
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AI summary
Apparatus and processes for removing dioxane from a composition, e.g., an ethoxylated fatty alcohol sulfate paste, utilize an evaporator having an inlet chamber and one or more heated channels. The process includes the step of heating the composition at a location upstream of the flow restriction to a temperature above the flashing temperature of water at a pressure of the channel inlet and applying a pressure to the heated composition to avoid such flashing. The process further includes the step of passing the pressurized, heated composition through the evaporator. The process can further include injecting a vapor into the channel. The purified, concentrated product can be diluted with water to a desired concentration.