Buffered Acid Composition for Stainless Steel Pickling
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Solution Overview
Problem
Existing pickling agents for stainless steel, particularly those using nitric acid, generate toxic nitrogen oxide fumes and nitrates, posing health and environmental hazards, while alternative agents like hydrogen peroxide and sulfuric acid are less effective.
Innovation Solution
A buffered acid composition is created by reacting liquid ammonia with hydrochloric acid, forming a weak base that effectively cleans and removes water-insoluble deposits without producing toxic fumes, through a Bronsted-Lowry reaction, and is processed under controlled temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitric acid is used in pickling agents, then cleaning effectiveness is improved, but toxic nitrogen oxide fumes and nitrates are generated
Solution Approach 1:
The patent changes the chemical composition parameters by replacing nitric acid with alternative oxidizing agents (hydrogen peroxide, sulfuric acid, Fe3+) and adjusting their concentrations to achieve effective pickling without generating toxic NOx fumes. The buffered acid composition uses specific pH ranges and component ratios to maintain effectiveness while eliminating harmful byproducts
Solution Approach 2:
The patent converts the harmful nitric acid oxidation process into a beneficial alternative by using hydrogen peroxide and other oxidizing agents that provide the necessary oxidation for scale removal without producing toxic nitrogen oxide fumes. The buffered system converts potential harmful side reactions into controlled, environmentally safe processes
2Object-generated harmful factors
If alternative oxidizing agents (hydrogen peroxide, sulfuric acid, Fe3+) are used, then toxic fumes are avoided, but cleaning effectiveness decreases
Solution Approach 1:
The patent creates a composite pickling composition by combining multiple oxidizing agents (hydrogen peroxide, sulfuric acid, Fe3+) with buffered acid components in specific ratios. This composite formulation synergistically enhances cleaning effectiveness while maintaining the environmental safety of using non-nitric acid-based oxidizers
Solution Approach 2:
The buffered acid composition serves multiple functions simultaneously: it provides oxidation for scale removal, maintains controlled pH levels, prevents harmful fume generation, and ensures effective cleaning across different stainless steel types. The single composition replaces multiple separate chemical processes
3Reliability
If nitrous acid is used in buffered acid compositions, then pH balancing is achieved, but toxic chloride ions remain in solution
Solution Approach 1:
The patent extracts and eliminates chloride ions from the solution by using alternative acid sources that do not introduce chloride contaminants. The buffered composition uses non-chloride-based acids and maintains pH balance through alternative mechanisms that do not rely on chloride-containing compounds
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 efficiently removes oxide discoloration, rust, and high temperature-related scale from stainless steel and other hard surfaces without the need for passivation, while being safe for human exposure and the environment, and can also balance pH in various fluids.
Implementation Method 1
The composition works by means of a Bronsted-Lowry reaction in which ammonium cations formed by protonation of the ammonia replace the ammonia as a base
Implementation Method 2
Next, the composition is placed under vacuum at 20 inches of mercury in pressure while continuing to heat said composition. Then, the buffered acid composition is placed under vacuum at 30 inches of mercury in pressure while continuing to be heated
Data Source
AI summary
A buffered acid composition created by the combination of liquid ammonia and an acid and a method for making the composition. The buffered acid composition is for use as a cleaning agent and for balancing the pH of a fluid.