Nitric-Sulfuric Acid Blend for Stainless Steel Cleaning
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Solution Overview
Problem
Current acid cleaners for stainless steel surfaces often face issues with corrosion, particularly when using high nitric acid, which can cause vapor staining and environmental concerns, and existing corrosion inhibitors like copper sulfate are not entirely effective or pose health risks.
Innovation Solution
Aqueous acid cleaning compositions combining nitric acid with sulfuric acid at specific weight ratios, which act as a corrosion inhibitor, reducing corrosion rates and environmental impact while maintaining cleaning effectiveness, and being more cost-effective than phosphoric acid-based cleaners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high nitric acid is used for cleaning stainless steel, then cleaning effectiveness is improved, but vapor staining and environmental harm increase
Solution Approach 1:
The patent changes the chemical composition parameters by using sulfuric acid instead of nitric acid as the primary cleaning agent, and adds specific corrosion inhibitors (nitric acid at 0.1-5% by weight, silicates, phosphates, or carboxylic acids) to maintain cleaning effectiveness while reducing vapor staining and environmental harm associated with high nitric acid formulations
Solution Approach 2:
The patent introduces intermediary substances (corrosion inhibitors such as nitric acid at low concentrations, silicates, phosphates, or carboxylic acids) that mediate between the cleaning action of sulfuric acid and the stainless steel surface, preventing harmful effects while maintaining cleaning effectiveness
2Reliability
If traditional corrosion inhibitors like copper sulfate are used, then corrosion protection is improved, but health risks and effluent disposal problems increase
Solution Approach 1:
The patent replaces expensive and problematic corrosion inhibitors like copper sulfate with cheaper, safer alternatives such as nitric acid at low concentrations (0.1-5% by weight), silicates, phosphates, or carboxylic acids, which provide effective corrosion protection without health risks or effluent disposal problems
Solution Approach 2:
The patent uses intermediary corrosion inhibitor substances (nitric acid at low concentrations, silicates, phosphates, or carboxylic acids) that protect the stainless steel surface from corrosion by sulfuric acid without introducing health risks or environmental contamination associated with copper sulfate
3Reliability
If phosphoric acid-based cleaners are used, then corrosion inhibition is improved, but cost increases
Solution Approach 1:
The patent replaces expensive phosphoric acid-based corrosion inhibitors with cheaper alternatives, specifically sulfuric acid combined with low-cost corrosion inhibitors such as nitric acid at 0.1-5% by weight, silicates, phosphates, or carboxylic acids, achieving effective corrosion inhibition at lower cost
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 compositions significantly reduce corrosion rates on stainless steel surfaces, achieving up to 99.97% lower corrosion compared to sulfuric acid alone, with negligible staining and reduced environmental impact, making them suitable for food and beverage processing equipment.
Implementation Method 1
Stainless steels have a passive film of chromium oxide that forms in the presence of oxygen due to the chromium present in the steel. This layer blocks most corrosion from spreading into the metal's internal structure.
Implementation Method 2
Acid cleaning is a process by which a solution of a mineral and/or organic acid in water sometimes in combination with a wetting agent or detergent or both, is employed to remove iron and other metallic contamination, light oxide films, soil and similar contaminants.
Implementation Method 3
The chromium forms a passive layer of chromium III oxide (Cr2O3) when exposed to oxygen.
Data Source
AI summary
The present invention relates to aqueous, sulfuric acid cleaners which employ the use of nitric acid as a corrosion inhibitor for cleaning metal and other surfaces, particularly stainless steel and for inhibiting corrosion. Method of use and manufacturing of the same are also disclosed.