pH-Adjusted PHA Agglomeration for Particle Size Control

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Solution Overview

Problem

Industrial separation and purification of poly-3-hydroxyalkanoic acid (PHA) produced by microorganisms face challenges in achieving PHA particles with arbitrary volume mean particle diameter and low contaminants without using salts, polymeric coagulants, or high temperature treatments, while minimizing organic solvent usage and preventing molecular weight reduction.

Innovation Solution

Adjusting the pH of the aqueous PHA suspension to an acidic region, preferably below 2, allows PHA agglomeration at a temperature lower than its melting point without adding coagulants, resulting in PHA agglomerates with reduced fine powders and superior productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If PHA particles are directly recovered as primary particles from aqueous suspension, then separation and purification are achieved, but fine powders increase making handling difficult

Engineering Contradiction:

ImprovePHA particle size controlVSAvoidProduct handling

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent changes the pH parameter of the aqueous suspension to an acidic region (pH 2-6), which causes PHA particles to aggregate into larger granules. This aggregation transforms the particle size distribution from fine primary particles to coarser agglomerates, improving handling properties while maintaining separation and purification effectiveness.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If salts or polymeric coagulants are added to aggregate PHA particles, then agglomeration is achieved, but separation of additives from PHA becomes difficult affecting quality

Engineering Contradiction:

ImprovePHA agglomeration efficiencyVSAvoidPHA purity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent utilizes the inherent properties of PHA in acidic conditions to achieve self-aggregation without external coagulants. By adjusting the pH to the acidic region, PHA particles naturally aggregate through electrostatic interactions and hydrophobic effects, eliminating the need for additive separation and maintaining high purity.

Inventive Principle:

Principle #25Self-service

3Productivity

If heating to around melting point of PHA is carried out to aggregate particles, then agglomeration is achieved, but molecular weight of PHA decreases

Engineering Contradiction:

ImprovePHA agglomerationVSAvoidPHA molecular weight

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent changes the pH parameter instead of using temperature as the aggregation mechanism. By adjusting pH to the acidic region, PHA aggregates at temperatures below its melting point, avoiding thermal degradation and molecular weight reduction while still achieving effective agglomeration.

Inventive Principle:

Principle #35Parameter changes

4Productivity

If aluminum sulfate or other coagulants are used to aggregate solids in slurry, then aggregation is achieved, but all components in aqueous suspension are aggregated not selectively aggregating PHA

Engineering Contradiction:

ImproveSolid-liquid separationVSAvoidPHA selective aggregation

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating specific acidic conditions (pH 2-6) that affect only PHA particles. This localized chemical environment causes selective aggregation of PHA while leaving other cellular components in the suspension unaffected, enabling selective separation based on pH-responsive properties of PHA.

Inventive Principle:

Principle #3Local quality

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 enables the production of PHA agglomerates with a volume mean particle diameter of at least 20 µm and low organic nitrogen content, avoiding quality issues and molecular weight reduction, while reducing contamination and organic solvent usage.

Implementation Method 1

adjusting the pH value of an aqueous suspension containing poly-3-hydroxyalkanoic acid to the acidic region, thereby obtaining agglomerates of the poly-3-hydroxyalkanoic acid

Methodology Applied

Scientific EffectAgglomeration: Coagulation

Data Source

PatentEP2366794B1Method for producing poly-3-hydroxyalkanoate and agglomerate of poly-3-hydroxyalkanoate

Publication Date: 2017.02.22 KANEKA CORP

AI summary

When industrially separating and purifying poly-3-hydroxyalkanoic acid produced by a microorganism, to obtain poly-3-hydroxyalkanoic acid agglomerates having an arbitrary volume mean particle diameter with favorable productivity and with decreased amount of an organic solvent used is enabled while decreasing contaminants derived from constitutive components of cellular bodies. According to the present invention, agglomerates of poly-3-hydroxyalkanoic acid are obtained by adjusting the pH of an aqueous poly-3-hydroxyalkanoic acid suspension to fall within an acidic region.