Reduced Graphene Oxide from Electrode Scrap via Acid Mixture

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Solution Overview

Problem

Conventional methods for producing reduced graphene oxide from graphite electrode scrap are complex, environmentally unfriendly, and time-consuming, making them inefficient at an industrial scale, and cannot easily transition from graphene production.

Innovation Solution

A method involving grinding graphite electrode scrap, followed by chemical oxidation with specific acids and oxidizing agents, and subsequent exfoliation and reduction using environmentally friendly agents like ascorbic acid, to produce reduced graphene oxide efficiently and quickly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional methods (CN107673338) are used to produce graphene from graphite electrode scrap through multiple steps including pretreatment, purification, and liquid phase stripping, then graphene can be obtained, but the process becomes extremely complex and time-consuming with over 10 sub-steps that are difficult to handle at industrial scale

Engineering Contradiction:
Improvegraphene production capabilityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple separate steps (pretreatment, purification, and exfoliation) into a single integrated oxidation step using a specific acid mixture (sulfuric acid, nitric acid, and phosphoric acid in specific ratios). This merging eliminates the need for separate pretreatment and purification steps, directly producing exfoliated graphite oxide that can be reduced to graphene oxide, thus simplifying the overall process while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The acid mixture serves multiple functions simultaneously: it acts as both the pretreatment agent and the oxidation/exfoliation reagent. The specific composition (H2SO4:HNO3:H3PO4 = 3:1:1 to 5:2:3) provides universal functionality for breaking down graphite structure, oxidizing carbon, and exfoliating layers in one step, replacing multiple specialized reagents and steps.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If conventional methods use extensive pretreatment and purification steps to process graphite electrode scrap, then material purity can be achieved, but the production time increases significantly reducing productivity

Engineering Contradiction:
Improvematerial purityVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The acid mixture is prepared in advance with specific ratios and concentrations optimized for simultaneous pretreatment and oxidation. The pre-mixed reagent system is designed to perform multiple functions in one application, eliminating the need for sequential pretreatment and purification steps, thus maintaining material purity while accelerating production.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If conventional methods use multiple chemical treatments including aluminum ion salt purification and centrifugal classification, then graphene quality can be maintained, but the process becomes environmentally unfriendly with extensive chemical waste

Engineering Contradiction:
Improvegraphene qualityVSAvoidchemical waste
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and eliminates the environmentally harmful steps from the conventional process. By removing the aluminum ion salt purification step and centrifugal classification, and replacing them with a single acid oxidation step followed by filtration, the method maintains graphene quality while significantly reducing chemical waste and environmental impact.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potentially harmful extensive chemical treatments into a beneficial simplified process. The specific acid mixture (including phosphoric acid which is less harmful than conventional reagents) transforms the harmful multi-step chemical process into a single controlled oxidation that produces fewer harmful byproducts while maintaining product quality.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If conventional methods use over 10 processing steps including pulverizing to 20-60 μm particles and multiple chemical treatments, then graphene can be synthesized, but the method duration extends significantly making it inefficient for industrial application

Engineering Contradiction:
Improvegraphene synthesis capabilityVSAvoidprocess duration
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent merges pulverizing, pretreatment, purification, and oxidation into a single integrated process. The acid mixture directly acts on the graphite electrode scrap (without requiring precise particle size control at 20-60 μm), performing all necessary transformations in one step, thereby dramatically reducing process duration while maintaining synthesis reliability.

Inventive Principle:
Principle #5Merging (Combining)

5Adaptability or versatility

If conventional methods are designed specifically for graphene production with complete reduction of oxygen groups, then pure graphene can be obtained, but the method cannot be transposed to produce reduced graphene oxide which has different properties and applications

Engineering Contradiction:
Improveproduct type flexibilityVSAvoidproduct quality consistency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces dynamic control in the reduction step. By using a controllable reducing agent system (hydrazine hydrate with specific concentration and treatment time parameters), the process can be adjusted to produce different oxidation states. This allows flexible production of either pure graphene (complete reduction) or reduced graphene oxide (partial reduction), maintaining quality consistency while enabling product versatility.

Inventive Principle:
Principle #15Dynamics

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

This method produces high-quality reduced graphene oxide in a shorter time with improved productivity and reduced environmental impact, overcoming the limitations of existing methods by simplifying the process and enhancing material purity and quality.

Implementation Method 1

an oxidation step of the grinded graphite electrode to obtain graphene oxide comprising the following successive sub-steps: i. The preparation of a mixture comprising the grinded graphite electrode, an acid and a nitrate salt... ii. The addition of an oxidizing agent... to obtain graphite oxide

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 2

the addition of a chemical element to stop the oxidation reaction, the chemical element being chosen from: an acid, non-deionized water, deionized water, H2O2 or a mixture thereof

Methodology Applied
Scientific EffectRedox Reactions: Redox Reactions

Implementation Method 3

v. The exfoliation of graphite oxide into graphene oxide

Methodology Applied
Scientific EffectUltrasonic Vibration: Ultrasonic Vibration

Data Source

PatentEP3797091B1A method for the manufacture of reduced graphene oxide from electrode graphite scrap
Publication Date: 2024.09.25 ARCELORMITTAL SA
  • EP3797091B1 patent drawingFigure 1~2

AI summary

The present invention relates to a method for the manufacture of reduced graphene oxide from electrode graphite scrap comprising the provision of the graphite electrode scrap, the grinding of electrode graphite scrap to obtain grinded graphite electrode, an oxidation step of the grinded graphite electrode to obtain graphene oxide and the reduction into reduced graphene oxide.