Reduced Graphene Oxide Manufacture from Kish Graphite
Solution Overview
Problem
Conventional methods for manufacturing reduced graphene oxide from Kish graphite are environmentally unfriendly and inefficient, involving multiple chemical treatments that generate toxic gases and require long processing times, making them difficult to manage at an industrial scale.
Innovation Solution
A method involving sieving, flotation, and acid leaching of Kish graphite, followed by oxidation with ammonium nitrate and controlled oxidation to produce graphene oxide, which is then reduced using a environmentally friendly reducing agent, resulting in high-purity reduced graphene oxide with reduced oxygen content and smaller lateral size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional Hummer Method is used for oxidation with sodium nitrate, sulfuric acid and potassium permanganate, then graphene oxide can be produced, but toxic gases such as NO2, N2O4 and NH3 are generated which are not environmentally friendly
Solution Approach 1:
The patent changes the chemical parameters of the oxidation process by replacing sodium nitrate with ammonium nitrate and adjusting the oxidizing agent to potassium dichromate or sodium chlorate, thereby eliminating toxic gas generation while maintaining effective oxidation of graphite to graphene oxide
Solution Approach 2:
The patent converts the harmful effect of nitrate decomposition into a beneficial outcome by using ammonium nitrate instead of sodium nitrate, which decomposes to produce nitrogen and water vapor instead of toxic nitrogen oxides, thus eliminating environmental harm while preserving the oxidation function
2Manufacturing precision
If chemical pretreatment composition is used for purification of Kish graphite, then the graphite can be purified, but a lot of chemical waste has to be treated and the stability of composition is difficult to control
Solution Approach 1:
The patent extracts and removes the problematic chemical pretreatment composition step entirely, replacing it with a simplified acid leaching process using only dilute sulfuric acid or hydrochloric acid, thereby eliminating the need for complex multi-component chemical compositions and their associated waste treatment issues
Solution Approach 2:
The patent makes the acid leaching step serve multiple functions simultaneously: it acts as both the pretreatment and purification step, eliminating the need for separate flushing and purification steps while achieving effective graphite purification
3Manufacturing precision
If flushing process and purification process are used for pretreatment of Kish graphite, then the graphite can be purified, but the productivity is slowed due to long preparation time
Solution Approach 1:
The patent merges the flushing process and purification process into a single acid leaching step, combining multiple sequential operations into one unified process that achieves the same purification effect in less time, thereby improving productivity without sacrificing purification quality
4Manufacturing precision
If reduction of graphene oxide is performed during 24 hours, then reduced graphene oxide can be obtained, but the productivity is very low
Solution Approach 1:
The patent changes the physical parameters of the reduction process by increasing temperature to 90-110°C and optimizing the reducing agent concentration and type, thereby reducing the reduction time from 24 hours to 2-6 hours while maintaining high-quality reduced graphene oxide production
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 produces high-quality reduced graphene oxide with reduced oxygen content and smaller lateral size, is less polluting, and significantly reduces processing time, making it more efficient and suitable for industrial-scale production.
Implementation Method 1
an oxidation step of the pre-treated kish-graphite obtained after step B) in order to obtain graphene oxide comprising the following successive sub-steps: i. the preparation of a mixture comprising the pre-treated kish-graphite, an acid and ammonium nitrate (NH4NO3)
Implementation Method 2
D. a reduction of graphene oxide into reduced graphene oxide
Implementation Method 3
ii. a flotation step with the fraction b) of kish graphite having a size above or equal to 50 μm
Implementation Method 4
iii. an acid leaching step wherein an acid is added so that the ratio in weight (acid amount)/(kish graphite amount) is between 0.25 and 1.0
Data Source
AI summary
A method for the manufacture of reduced graphene oxide from Kish graphite including the pretreatment of kish graphite, the oxidation of pre-treated kish graphite into graphene oxide and the reduction of graphene oxide into reduced graphene oxide, the reduced graphene oxide and the use of the graphene oxide.