Ethanol in water: the invisible challenge in industrial and environmental detection
The detection of ethanol in water represents a significant technical challenge in industrial and environmental settings. Unlike oils and heavy fuels, which easily separate from water and float on its surface, ethanol is completely miscible. This property eliminates one of the main strategies employed for hydrocarbons regarding the observation or verification of a separate surface layer, rendering traditional methods ineffective when the alcohol is present in a diluted form.
Why do conventional methods fail?
The total miscibility of ethanol in water prevents the formation of distinct phases and makes it impossible for sensors based on differential electrical conductivity, buoyancy or refractive indices to operate. In aqueous solutions, the conductivity of the mixture varies little until high concentrations are reached, compromising the performance of electrochemical sensors. In addition, the refractive index of ethanol is relatively close to that of water, which makes it difficult to use optical sensors.
These limitations become critical in contexts with strict environmental controls, such as biofuel storage areas, industrial effluent treatment plants, refineries, chemical plants and fuel ethanol plants. In these locations, potential leaks in drainage systems, containment basins or the water table represent an environmental risk and also threaten operational safety, especially in potentially explosive atmospheres.
The rapid dispersion of ethanol in water further complicates the detection process, drastically reducing its concentration at fixed sampling points. This characteristic requires sensors capable of continuous and sensitive monitoring, revealing small variations in composition in real time. The lack of reliable methods to signal the onset of a leak or infiltration prevents preventive actions and keeps operators dependent on periodic laboratory analyses or manual inspections, which rarely provide quick and effective responses.
Emerging Technology: Electromagnetic Absorption Sensors
In response to this need, emerging technologies seek to overcome the limitations of conventional methods. One such approach is based on high-frequency electromagnetic absorption, a technique that uses differences in the dielectric properties of liquids. Water absorbs this energy more intensely than ethanol, allowing continuous and proportional detection of the presence of alcohol in the mixture, even at relatively low concentrations.
Solutions based on this principle have been incorporated into modern industrial sensors capable of operating in liquid environments or in intermittently dry areas, such as sumps, drainage channels and tanks with variable levels. A recent example is the ID-223ET sensor designed by Leakwise specifically to observe the presence of ethanol in water, even when diluted from 10%. Embedded with transmitting and receiving antennas, the floating sensor remains stable at the liquid-air interface and continuously monitors the signal absorption.
As the concentration of ethanol in the water increases, there is a reduction in the absorption rate of the electromagnetic signal, allowing the system to infer the presence and proportion of alcohol in the mixture. This variation is converted into a continuous analog signal, providing an automated, real-time monitoring system.
With the increasing use of ethanol as a fuel and industrial input, the demand for robust and sensitive solutions for its detection in liquid systems is also growing. The introduction of technologies such as the ID-223ET sensor represents a significant advance in the response to leaks or contamination by miscible substances, filling a historical gap in industrial monitoring systems. By enabling the continuous identification of ethanol diluted in water, even under complex operating conditions, this technology offers an effective alternative to increase operational safety, improve environmental control and meet regulatory requirements.