Citric and Ascorbic Acid Reagent for Soil Decontamination

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Solution Overview

Problem

Current methods for decontaminating soils polluted with metals and radioactive nuclides are expensive, difficult to implement, and do not allow for the reuse of treated soils, as they leave residual waste and require complex installations.

Innovation Solution

A process using a combination of citric acid and ascorbic acid, in specific proportions, to form complexes with metals and radioactive nuclides, allowing for their effective separation and removal from soils at ambient temperature, without producing secondary waste, and enabling the reuse of treated soils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional decontamination methods (vitrification, complexation) are used, then radioactive waste is trapped in soil, but the soil cannot be reused and the process is expensive and difficult to implement

Engineering Contradiction:
Improvedecontamination effectivenessVSAvoidsoil reusability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent extracts radioactive contaminants from soil using a leaching solution containing citric acid and ascorbic acid. The solution selectively dissolves radioactive metals and nuclides from the soil matrix, separating them from the soil particles. This extraction approach allows the soil to be recovered and reused while removing the contaminants to a separate stream for disposal or further treatment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical parameters of the leaching solution by using a specific combination of citric acid (a chelating agent) and ascorbic acid (a reducing agent). This parameter change enables the solution to effectively bind and solubilize radioactive contaminants under ambient conditions, achieving both effective decontamination and soil reusability without requiring extreme temperatures or pressures.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional decontamination methods are used, then radioactive waste is trapped, but the process is expensive and difficult to implement

Engineering Contradiction:
Improvedecontamination effectivenessVSAvoidimplementation complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a disposable leaching solution based on citric acid and ascorbic acid that can be applied to contaminated soil and then discarded or regenerated. This approach eliminates the need for expensive, complex equipment required by conventional methods like vitrification. The simple chemical solution can be prepared and applied using basic mixing and filtration equipment, significantly reducing implementation complexity and cost.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Loss of substance

If leaching with citrate and reducing agent is used, then 70% of contaminants are removed, but the process requires multiple reagents and complex formulations

Engineering Contradiction:
Improvecontaminant removal efficiencyVSAvoidreagent formulation complexity
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple reagents (citrate complexing agent and ascorbic acid reducing agent) into a single integrated leaching solution. This combination achieves effective contaminant removal through synergistic action: citric acid chelates radioactive metals while ascorbic acid reduces them to more soluble forms. The unified formulation simplifies the process compared to using separate treatment steps, reducing operational complexity while maintaining high removal efficiency.

Inventive Principle:
Principle #5Merging (Combining)

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 process achieves complete decontamination of soils, allowing for their reuse in agriculture, industry, or housing, while being cost-effective and practical to implement, with the added benefit of recycling treatment water and potentially recovering valuable materials.

Implementation Method 1

mixing of the contaminated soil with (industrial) treatment water comprising a combination of reagents consisting of a mixture of citric acid and ascorbic acid

Methodology Applied
Scientific EffectComplexation: Chemical Bonding

Implementation Method 2

The reagent combination consists of citric acid and ascorbic acid, excluding any other compound... formation of complexes (citrate compounds)

Methodology Applied
Scientific EffectChelation: Chemical Bonding

Implementation Method 3

separation of the remediated soil and the (industrial) treatment water containing acid complexes (citric acid and ascorbic acid) and radioactive metals and/or nuclides by removing the (industrial) treatment water under continuous mixing and pumping

Methodology Applied
Scientific EffectSeparation by pumping and mixing: Stirring

Data Source

PatentEP3077131B1Combination of reagents and method for removing pollution from polluted soils using the same
Publication Date: 2019.09.25 DE LOES PIERRE
  • EP3077131B1 patent drawingFigure 1

AI summary

The present invention provides a reagent combination and a method, which uses said effective reagent combination, to remove pollution from ground polluted by metals and/or radioactive nuclides. Said method is practical to use and inexpensive. The reagent combination comprises about 80 to 90 wt% of citric acid and about 10 to 20 wt% of ascorbic acid in relation to the total weight of the reagent combination, preferably about 85 wt% of citric acid and 15 wt% of ascorbic acid in relation to the total weight of the reagent combination.