Citric Acid Instrument Reprocessing for Scale Removal and Passivation

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Solution Overview

Problem

Existing cleaning compositions for health care instruments and metal surfaces fail to effectively remove scale deposits and rust stains while maintaining the passive layer, leading to corrosion and reduced lifespan, and they often contain phosphorus which is environmentally undesirable.

Innovation Solution

A neutralizer, destainer, and passivating composition comprising citric acid, a nonionic surfactant, and water, which is substantially phosphorus-free, effectively removes scale deposits and rust stains while restoring the passive layer on metal surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphorus-based cleaning compositions are used to remove scale deposits and stains, then cleaning effectiveness is improved, but environmental harm increases and regulatory compliance deteriorates

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidenvironmental harm

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces phosphorus-based cleaning agents with acid-based compositions (citric acid, lactic acid, oxalic acid, tartaric acid, or malic acid), fundamentally changing the chemical parameter of the cleaning composition to achieve effective scale and stain removal without phosphorus-related environmental harm

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses biodegradable organic acids that break down quickly and environmentally friendly, replacing persistent phosphorus-based chemicals with naturally degradable alternatives that provide effective cleaning without long-term environmental accumulation

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If harsh cleaning conditions are applied to remove scale deposits and stains, then cleaning effectiveness is improved, but metal surface corrosion increases and passive layer damage worsens

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidsurface corrosion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses mild organic acids (citric acid, lactic acid, oxalic acid, tartaric acid, or malic acid) instead of harsh alkaline cleaners, changing the pH parameter to provide effective cleaning while maintaining the passive layer and preventing metal surface corrosion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of acid-based cleaning into benefit by selecting specific organic acids that effectively remove scale and stains while simultaneously being gentle enough to protect the metal passive layer, thus turning a potentially corrosive action into a protective cleaning process

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If repeated instrument reprocessing cycles are performed to ensure adequate cleaning, then infection control is improved, but instrument lifespan decreases and functionality deteriorates

Engineering Contradiction:

Improveinfection controlVSAvoidinstrument lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical parameters of the reprocessing composition to use mild organic acids that effectively clean instruments while protecting metal surfaces from corrosion during repeated processing cycles, thus extending instrument lifespan

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies a protective acid-based composition that prevents corrosion and passive layer damage before it can occur during repeated reprocessing cycles, cushioning the instruments against the cumulative effects of harsh cleaning conditions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 composition achieves effective scale control and passivation, prolonging the lifespan of metal surfaces by maintaining the passive layer and preventing corrosion without causing discoloration, as demonstrated by ASTM passivation tests.

Implementation Method 1

The composition comprises at least one acid comprising citric acid... effectively removes scale deposits and rust stains

Methodology Applied

Scientific EffectChelation:

Implementation Method 2

A neutralizer, destainer, and passivating composition comprising citric acid... effectively removes scale deposits and rust stains

Methodology Applied

Scientific EffectAcid-base reaction:

Implementation Method 3

A neutralizer, destainer, and passivating composition... restoring the passive layer on metal surfaces

Methodology Applied

Scientific EffectNeutralization:

Data Source

PatentUS12351775B2Neutralizing instrument reprocessing

Publication Date: 2025.07.08 ECOLAB USA INC

AI summary

A neutralizer, destainer/descaling, and passivating composition and methods of using the same on metal surfaces are disclosed. The compositions are particularly well suited for the treatment of health care surfaces and other hard surfaces in need of treatment. In particular, the neutralizer, destainer/descaling, and passivating composition is an acid-based composition for use in instrument reprocessing.