Acylation Process Membrane Fouling Prevention
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Solution Overview
Problem
The existing polysaccharide acylation processes face challenges in efficiently recovering acylated polysaccharides and removing organic impurities without clogging filtration membranes, often requiring surface-active agents like lignosulfonates, especially in aqueous waste streams from polysaccharide acylation processes.
Innovation Solution
A process involving the reaction of polysaccharides with an acylating agent, followed by washing with water containing low Ca2+ ions (0.05 to 15 mg/l), allowing for nanofiltration or reverse osmosis without surface-active agents, effectively recovering acylated polysaccharides and carboxylic acids while preventing membrane fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface-active agents like lignosulfonates are added to aqueous waste streams, then organic impurities can be removed and membrane fouling is prevented, but the process complexity and chemical usage increase
Solution Approach 1:
The patent extracts and removes the harmful organic impurities (hemicelluloses) from the aqueous waste stream through nanofiltration or reverse osmosis membranes before they can cause fouling. This eliminates the need for surface-active agents by directly separating the problematic substances rather than using chemical additives to prevent their adverse effects.
Solution Approach 2:
The patent introduces an intermediary substance (Ca2+ ions at controlled concentrations of 0.05 to 15 mg/l) that modifies the properties of organic impurities to prevent them from adhering to membrane surfaces. This intermediary approach allows the system to handle impurities without requiring surface-active agents, thus reducing process complexity while maintaining fouling prevention.
2Manufacturing precision
If nanofiltration or reverse osmosis is applied to remove organic impurities, then purification efficiency increases, but membrane clogging occurs without proper pretreatment
Solution Approach 1:
The patent applies preliminary action by adding Ca2+ ions to the aqueous waste stream before nanofiltration or reverse osmosis treatment. This pre-treatment step modifies the organic impurities (hemicelluloses) to reduce their tendency to foul membranes, ensuring that the subsequent high-precision filtration does not result in clogging. The Ca2+ concentration is carefully controlled at 0.05 to 15 mg/l to achieve optimal pretreatment效果.
3Productivity
If surface-active agents are used to prevent agglomeration of impurities, then filtration performance is maintained, but operational costs and environmental impact increase
Solution Approach 1:
The patent applies self-service by using Ca2+ ions to induce a beneficial effect where the organic impurities (hemicelluloses) themselves become less problematic. The Ca2+ ions modify the impurities' properties to prevent agglomeration and fouling inherently, eliminating the need for external surface-active agents. This self-service approach maintains filtration performance while avoiding additional chemical usage and associated costs.
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 approach enables efficient recovery of acylated polysaccharides and carboxylic acids in high purities, allowing for recycling and minimizing membrane clogging, even at high volume reductions, without the need for surface-active agents, thus improving the polysaccharide acylation process efficiency.
Implementation Method 1
it has surprisingly been found that precipitation of calcium salts can be prevented if the concentration of Ca2+ ions in the water used is equal to or lower than 15 mg/l
Implementation Method 2
the aqueous phase is subjected to at least one nanofiltration or reverse osmosis step to recover a permeate containing carboxylic acid
Data Source
AI summary
The invention concerns a process for the manufacture of an acylated polysaccharide which comprises. (a) reacting a polysaccharide with an acylating agent to produce an acylated polysaccharide and (b) washing the acylated polysaccharide with water containing from 0.05 to15mg/l Ca2+-ions. (c) recovering the washed acylated polysaccharide and an aqueous phase containing carboxylic acid from step (b).