Expanded Graphite Adsorption for Hydrocarbon Removal
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Solution Overview
Problem
Current methods for treating water contaminated with low concentrations of dispersed or emulsified hydrocarbons, such as those found in produced water, are inefficient and costly, requiring long treatment times and producing secondary contamination due to the use of chemical reagents.
Innovation Solution
A process utilizing expanded graphite with specific surface area, apparent density, and carbon:oxygen ratio characteristics, mixed at high speeds to effectively adsorb and separate hydrocarbons from water, allowing for rapid separation and filtration to achieve stringent decontamination within 30 minutes or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical/physical processes are used for treating produced water, then treatment effectiveness is improved, but treatment cost increases significantly
Solution Approach 1:
The patent changes the physical parameters of graphite by expanding it to increase surface area from typical values to 50-100 m²/g, and controls the carbon:oxygen ratio ≥100 to optimize hydrophobicity. These parameter changes enable the graphite to effectively adsorb hydrocarbons at low concentrations without requiring expensive chemical reagents, thus improving treatment effectiveness while controlling costs.
Solution Approach 2:
The patent uses expanded graphite as a disposable adsorbent material that can be easily separated from water after use. The graphite is applied in small quantities (0.1-10 g per liter of water) and then removed with the adsorbed hydrocarbons, eliminating the need for expensive chemical regents and complex treatment systems.
2Reliability
If chemical reagents are used for hydrocarbon removal, then decontamination efficiency is improved, but secondary contamination is produced
Solution Approach 1:
The patent converts the naturally hydrophobic property of graphite into a beneficial adsorption mechanism. The expanded graphite's hydrophobic surfaces automatically attract and bind hydrocarbon molecules from water through physical adsorption, eliminating the need for chemical reagents that would cause secondary contamination. The process uses the material's inherent properties rather than chemical reactions.
3Reliability
If conventional adsorption methods are used for low concentration hydrocarbons, then treatment time is extended, but removal efficiency is maintained
Solution Approach 1:
The patent achieves rapid adsorption (within 5-30 minutes) by changing two key parameters of graphite: expanding it to increase surface area to 50-100 m²/g, and maintaining a high carbon:oxygen ratio ≥100 to optimize hydrophobicity. These parameter changes dramatically increase the adsorption kinetics, allowing efficient removal of low concentration hydrocarbons (≤1 g/l) in a practical time frame suitable for industrial applications.
Solution Approach 2:
The patent segments the graphite structure into expanded flake forms with increased surface area and controlled morphology. This segmentation increases the available adsorption sites and improves mass transfer kinetics, enabling rapid adsorption of hydrocarbons from water without requiring extended treatment times.
4Quantity of substance
If expanded graphite with high surface area is used, then adsorption capacity is improved, but separation from water becomes more difficult
Solution Approach 1:
The patent optimizes the apparent density of expanded graphite to a specific range (0.5-5.0 g/l) that balances adsorption capacity with separability. This density parameter ensures the graphite floats on water for easy removal while maintaining sufficient surface area (50-100 m²/g) for effective adsorption. The controlled carbon:oxygen ratio ≥100 further ensures hydrophobicity, preventing water absorption that would complicate separation.
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 significantly reduces treatment time, achieving maximum hydrocarbon adsorption in under 30 minutes, with the ability to reuse expanded graphite for multiple cycles, effectively bringing residual hydrocarbon content below regulatory limits while minimizing graphite residues in the treated water.
Implementation Method 1
mixing said expanded graphite with said water containing hydrocarbons in a vessel, whereby said hydrocarbons are adsorbed by said expanded graphite
Implementation Method 2
allowing said expanded graphite containing said adsorbed hydrocarbons to separate from said water and form a layer of expanded graphite on the top of said water
Data Source
AI summary
Process for the treatment of water containing low quantities of hydrocarbons (as dispersed or dissolved or emulsified) by means of expanded graphite having an apparent density from 2 to less than 5 g/l, wherein said hydrocarbons are present in a quantity less than or equal to 1 g/l, a specific surface area from 50 to 100 m2/g and a carbon/oxygen ratio (C:O)≥100. The expanded graphite is mixed vigorously for a short time with the water contaminated by hydrocarbons and easily separated at the end of the treatment.