pH-Responsive PEI Suds Collapser for Laundry Detergent
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Solution Overview
Problem
Laundry detergents used for hand washing often require multiple rinses to remove surfactant residue, leading to excessive water usage, especially in water-scarce regions, while traditional suds suppressors fail to distinguish between wash and rinse cycles, compromising cleaning efficiency and user perception.
Innovation Solution
An alkaline laundry detergent containing an anionic surfactant and a polyethyleneimine (PEI) suds collapser, activated by pH drop during the rinse cycle, which attracts and complexes with the anionic surfactant to promote faster suds collapse, reducing the need for rinsing without sacrificing cleaning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional suds suppressors are used, then suds volume is reduced, but cleaning efficiency is compromised and user perception of surfactant sufficiency is negative
Solution Approach 1:
The patent applies dynamics by making the suds suppression function conditional rather than static. The polyethyleneimine suds collapser remains inactive during the wash cycle (when alkaline conditions prevail) and becomes active only during the rinse cycle (when pH drops). This dynamic behavior allows the system to provide suds during washing for user satisfaction while collapsing suds during rinsing to reduce water usage, thereby resolving the contradiction between maintaining cleaning perception and reducing rinse requirements.
Solution Approach 2:
The patent utilizes parameter changes, specifically pH change, to control the functionality of the suds collapser. The polyethyleneimine polymer's charge state and surfactant-binding capability change with pH: at alkaline pH during washing, the polymer is less protonated and less effective at binding surfactant, allowing suds formation; at lower pH during rinsing, the polymer becomes more protonated and effectively binds surfactant, collapsing suds. This parameter-based control resolves the contradiction by enabling context-dependent suds management.
2Reliability
If multiple rinses are performed to remove surfactant residue, then cleaning completeness is improved, but water consumption increases significantly
Solution Approach 1:
The patent introduces polyethyleneimine as an intermediary substance that mediates between the surfactant and the rinse water. This polymer acts as a surfactant binder that captures residual surfactant during the rinse cycle, forming complexes that can be more easily removed. The intermediary enables effective surfactant removal with fewer rinses, thus improving cleaning completeness while reducing water consumption.
Solution Approach 2:
The patent applies extraction by actively removing surfactant during the rinse cycle through the polyethyleneimine suds collapser. The polymer extracts bound surfactant from the fabric and rinse water, concentrating it in removable complexes. This active extraction mechanism allows for more effective surfactant removal in fewer rinses compared to passive rinsing, resolving the contradiction between cleaning completeness and water consumption.
3Loss of substance
If acidic compositions with fatty acids are used to collapse suds, then rinse water usage is reduced, but cleaning efficiency of greasy soils is sacrificed
Solution Approach 1:
The patent applies periodic action by separating the washing and rinsing functions into distinct phases with different chemical conditions. The wash cycle maintains alkaline conditions optimal for cleaning greasy soils, while the rinse cycle transitions to lower pH conditions that activate the suds collapser. This periodic alternation between different chemical environments allows the system to achieve both effective cleaning and reduced rinse water usage, resolving the contradiction present in continuously acidic compositions.
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 solution significantly reduces the number of rinses required, conserving water and resources while maintaining effective cleaning performance, as the PEI suds collapser effectively collapses suds during the rinse cycle, addressing the issue of excessive water usage and user perception of surfactant residue.
Implementation Method 1
The polyethyleneimine suds collapser is typically activated by the pH drop during the rinse such that the now protonated amines attract and/or complex with the anionic surfactant during the rinse.
Implementation Method 2
The polyethyleneimine suds collapser is typically activated by the pH drop during the rinse such that the now protonated amines attract and/or complex with the anionic surfactant during the rinse.
Data Source
AI summary
An alkaline laundry detergent for hand washing a fabric contains a sudsing surfactant, a polyethyleneimine suds collapser having the empirical formula (PEI)a(EO)b(PO)c where a is about 100-100,000, b is about 0-60, and c is about from 0-60, and a pH control system. When diluted to form a laundry liquor and during washing the pH control system maintains the pH of the laundry liquor above about 8.