Spent Sulfuric Acid Recycling via UV Gold Silver Nanoparticle Catalysis
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Solution Overview
Problem
Existing methods for recycling spent sulfuric acid from both the semiconductor and chemical industries are inefficient, particularly in removing hydrogen peroxide (H2O2) and achieving effective heat recovery, leading to high energy costs and environmental concerns.
Innovation Solution
A method utilizing gold/silver bimetallic nanoparticles to catalyze the decomposition of H2O2 in spent acid under ultraviolet irradiation, followed by thermal decomposition to produce sulfur trioxide (SO3), which is then converted to sulfur dioxide (SO2) and further processed for heat recovery and regeneration of sulfuric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spent sulfuric acid from chemical industry is subjected to conventional recovery processes, then electronic-grade sulfuric acid can be produced, but the energy cost becomes excessively high making it financially unfeasible
Solution Approach 1:
The patent changes the operational parameters by introducing ultraviolet irradiation to activate the catalyst and controlling the temperature range (20-100°C) for the catalytic decomposition of H2O2. These parameter modifications enable the process to achieve high purity sulfuric acid production with significantly reduced energy consumption compared to conventional high-temperature recovery processes
Solution Approach 2:
The patent replaces conventional thermal decomposition methods with a catalytic system activated by ultraviolet light. Instead of relying solely on high-temperature heating to decompose H2O2 and regenerate sulfuric acid, the system uses photoactivated catalysis, which dramatically reduces the energy input required while maintaining product purity
2Productivity
If hydrogen peroxide is present in spent acid, then the acid can be used for photoresist stripping in semiconductor manufacturing, but it causes container and pipeline leakage creating safety hazards
Solution Approach 1:
The patent extracts and removes hydrogen peroxide from the spent sulfuric acid solution through catalytic decomposition. The H2O2 is converted into water and oxygen gas, which are then separated from the sulfuric acid product. This extraction eliminates the harmful corrosive and oxidizing properties of H2O2 while preserving the useful sulfuric acid for recycling
Solution Approach 2:
The patent converts the harmful hydrogen peroxide into beneficial products - water and oxygen. The H2O2 that previously caused safety hazards is transformed through catalytic decomposition into harmless water and useful oxygen gas, turning a safety risk into a beneficial outcome
3Loss of energy
If conventional heat recovery methods are used in spent acid recovery, then some energy can be recovered, but the heat recovery efficiency remains insufficient to make the process financially viable
Solution Approach 1:
The patent implements continuous heat recovery through multiple heat exchangers arranged in series. The hot sulfuric acid continuously transfers heat to process water and steam generation systems throughout the entire flow path, maximizing energy extraction at multiple stages rather than relying on a single heat recovery point
Solution Approach 2:
The patent utilizes phase transitions of water (liquid to vapor) in the steam generation system to recover energy. By heating process water to generate steam, the system captures latent heat during the phase change, significantly improving overall heat recovery efficiency compared to simple sensible heating
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 method effectively removes H2O2 from spent acid, improves heat recovery efficiency, reduces energy costs, and enables sustainable circulation of electronic-grade and industrial-grade sulfuric acid, thereby minimizing environmental impact.
Implementation Method 1
A method utilizing gold/silver bimetallic nanoparticles to catalyze the decomposition of H2O2 in spent acid under ultraviolet irradiation
Implementation Method 2
gold/silver bimetallic nanoparticles to catalyze the decomposition of H2O2 in spent acid under ultraviolet irradiation
Implementation Method 3
followed by thermal decomposition to produce sulfur trioxide (SO3), which is then converted to sulfur dioxide (SO2)
Implementation Method 4
Heat recovery from thermal decomposition, exothermic catalytic conversion and SO3 absorption is typically in the form of high-pressure superheated steam
Implementation Method 5
SO3 absorption
Implementation Method 6
Heat recovery from thermal decomposition, exothermic catalytic conversion and SO3 absorption
Data Source
AI summary
The present invention provides a method for recycling sulfuric acid from various industries. The recovery system is constructed that it can process spent acid containing H2O2 and recover waste heat to save energy. The heat from the spent acid recovery process is used to generate electric energy, hot water, and chilled water to reduce its energy consumption, operating cost, and carbon emissions. This system can produce electronic-grade and industrial-grade sulfuric acid at the same time and solve the problem of spent acid disposal from various industries.