PHA Filter Cake Washing for Thermal Stability at Mild pH
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Solution Overview
Problem
Existing methods for producing polyhydroxyalkanoate (PHA) require the use of corrosion-resistant devices due to the high acidity needed for thermal stability, leading to increased costs and potential degradation, and there is a need for a method that maintains thermal stability without such devices.
Innovation Solution
A method involving filter-pressing filtration and through-washing of PHA filter cakes to a pH of 4.0 to 5.5, removing catalyst impurities and achieving thermal stability without the need for corrosion-resistant equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pH of aqueous PHA suspension is maintained at not less than 2.5 and less than 4.0 to ensure thermal stability, then thermal stability of PHA is improved, but corrosion-resistant devices are required increasing cost and complexity
Solution Approach 1:
The patent extracts and removes catalyst impurities from the PHA product through a series of washing steps (water washing, alkali solution washing, acid solution washing). This extraction of harmful catalysts allows the PHA to achieve thermal stability without requiring corrosion-resistant equipment, as the remaining pH level (4.0-5.5) is no longer corrosive enough to demand specialized devices.
Solution Approach 2:
The patent changes the pH parameter from the initial acidic range (2.5-4.0) to a higher, non-corrosive range (4.0-5.5) through systematic washing. This parameter transformation maintains thermal stability while eliminating the need for corrosion-resistant devices, directly resolving the technical contradiction.
2Reliability
If acid solution is used to maintain low pH for thermal stability, then thermal stability is improved, but plastic waste generation increases
Solution Approach 1:
The patent implements a multi-stage washing process that discards acid solution and replaces it with water and alkali solutions to achieve pH adjustment. This recovery approach eliminates the need to continuously use fresh acid solution, reducing plastic waste generation while maintaining the thermal stability of the PHA product.
3Reliability
If filtration is performed at low pH to maintain thermal stability, then thermal stability is improved, but manufacturing complexity increases due to corrosion-resistant equipment
Solution Approach 1:
The patent performs preliminary washing actions (water washing, alkali washing, acid washing) before the final filtration and drying steps. This preliminary removal of catalyst impurities ensures that subsequent manufacturing steps can be performed with standard equipment rather than corrosion-resistant equipment, simplifying the overall manufacturing process while maintaining thermal stability.
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 method produces PHA with enhanced thermal stability and reduces plastic waste generation, aligning with sustainable development goals by eliminating the need for corrosion-resistant devices.
Implementation Method 1
a compression step of supplying an aqueous PHA suspension having a pH of not less than 2.5 and less than 4.0 to a filter press and compressing the aqueous PHA suspension
Implementation Method 2
a through washing step of through-washing a filter cake obtained by the compression step, until the filter cake has a pH of 4.0 to 5.5
Data Source
AI summary
An object is to provide a PHA having good thermal stability, even in a pH range in which use of a corrosion-resistant device is not needed. The object is attained by a method for producing a PHA, including: a filter-pressing filtration step including a compression step of compressing an aqueous PHA suspension having a pH of not less than 2.5 and less than 4.0 with use of a filter press; and a through washing step of through-washing a filter cake obtained by the compression step, until the pH becomes 4.0 to 5.5.