Biochar Pervious Concrete for Passive NOx Absorption
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Solution Overview
Problem
Existing concrete compositions for air pollutant removal, such as nitrogen oxides (NOx), sulfur oxides, ozone, and volatile organic compounds, rely on expensive, non-renewable materials like activated carbon, and there is a need for more effective and environmentally friendly alternatives with reduced carbon footprints.
Innovation Solution
A pervious concrete composition using pyrogenic carbonaceous material, such as biochar, with specific surface areas and porosity characteristics, is developed to enhance the absorption of NOx and other pollutants, replacing traditional activated carbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated carbon is used as adsorbent in concrete, then air pollutant absorption performance is improved, but production cost and carbon footprint increase due to expensive non-renewable resources and high-temperature calcination
Solution Approach 1:
The patent replaces expensive activated carbon with biochar, a cheaper adsorbent material derived from renewable biomass waste. Although biochar has lower production cost, the patent ensures adequate service life by optimizing its incorporation into concrete matrix, allowing the concrete structures to serve as long-term air purification systems without frequent replacement
Solution Approach 2:
The patent changes the production parameters of the adsorbent material by using low-temperature pyrolysis (350-750°C) of renewable biomass instead of high-temperature calcination (800-1100°C) of fossil-based materials. This parameter change reduces energy consumption and carbon footprint while maintaining adsorption functionality
2Reliability
If activated carbon is used in concrete, then NOx absorption is achieved, but specific surface area requirement increases production complexity
Solution Approach 1:
The patent changes the particle size parameters of biochar to optimize the balance between specific surface area and absorption performance. By controlling particle size distribution and incorporating biochar at optimized dosages (5-20% by weight), the patent achieves effective NOx absorption without requiring excessively high specific surface area, thereby simplifying the overall system
3Reliability
If photocatalytic oxides are used in concrete, then urban NOx pollutants are reduced, but production cost increases due to expensive nanosized additives
Solution Approach 1:
The patent replaces expensive nanosized photocatalytic oxides with biochar, a low-cost adsorbent derived from renewable biomass. This substitution significantly reduces material costs while maintaining air purification functionality through adsorption mechanisms, making the technology economically viable for widespread construction applications
Solution Approach 2:
The patent utilizes renewable biomass waste as feedstock for biochar production, transforming waste materials into valuable air purification components. This self-service approach converts available organic waste resources into functional building materials, reducing dependency on expensive imported or synthetically produced additives
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 biochar-based pervious concrete demonstrates improved NOx absorption performance compared to activated carbon, even with lower specific surface area, offering a cost-effective and sustainable solution for air pollutant mitigation.
Implementation Method 1
Adsorption technology within concrete is also reported in literature... The resulting concrete compositions thus passively adsorbs air pollutants
Implementation Method 2
it was found that when used at same addition rate biochar offers increased NOx absorption compared to activated carbon
Data Source
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AI summary
The invention relates to a pervious concrete based on: • a cement, • a particulate pyrogenic carbonaceous material obtained from biomass pyrolysis, said pyrogenic carbonaceous material having a specific surface area ranging from 300 to 1000 m2/g, and • aggregates, said pervious concrete having an porosity of at least 10%, preferably ranging from 10% to 50%, expressed as a percentage with respect to the volume of the final hardened concrete. The invention further relates to the use of the pervious concrete of the invention for removing, at least in part, from the atmosphere gases and volatile compounds including nitrogen oxides, and preferably NOx, sulfur oxides, volatile organic compounds, ozone, carbon monoxide. The invention also relates to a method for preparing the pervious concrete of the invention.