Filtering Oil with Ferrofluids

The large number of oil spills in the Houston Bay area over the last two decades poses an immediate need for an efficient and cost-effective process for the separation of oil and water. Seeing the big impact oil spills has on the environment and my community, I decided to research different ways to solve the problem.

I discovered the recent popularity and advancement of nano-technology which has opened the door to a wide range of applications, which include a method for the capture of oil particles in water using a ferrofluid (a homogeneous mixture of ferromagnetic particles suspended in a carrier fluid). I paired up with three amazing students that had a similar interest in making their final undergraduate project fun and impactful!

Statement Goal:

‍To demonstrate the application of ferrofluid technology for the removal of suspended oil droplets in a flowing water stream.

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Methodology

Researched ferro fluid properties and applications
Conducted multiple experiments to determine combability of the oil and the ferrofluid (Acrylic plates and vinyl tubing)
Developed and submitted proposal to Oil & Gas companies to get sponsorship of crude oil. (Sponsors: CoreLab & Shell)
Designed and tested three different prototypes of the filtration process.
Conducted a device evaluation for industrial application

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Prototyping

Before receiving crude oil sponsorship, the team and I conducted several experiments with different types of oils and ferrofluid.

I decided to test different concentrations of oil, water, and ferrofluid.

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The initial concept we pursued was mainly based on the implementation of an induced magnetic field using a helix type of arrangement around a pipe. This design was based on the idea that a helix form of a magnetic field would provide us with an effective oil and ferrofluid mixture. This concept was ultimately scrapped after discussing the difficulties of implementing a magnetic field that was strong enough and the inefficiencies of using coil and electric power.

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Prototype II was designed with a smaller inner diameter to obtain an optimal flow rate. The magnetic gradient and the T-connector were replaced by an arrangement of permanent neodymium magnets inside a filtration tower. Although there was a significant increase in the oil collection rate with the second prototype, the system was not continuous and lacked efficiency for meaningful application.

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Final Design

The final device consists of an initial container with separate reservoirs for the water and the magnetized oil. A set of actuated solenoid valves controls the inflow of oil and water into the system, and a peristaltic pump is connected to the magnetic arrangement and to help transport the oil into the appropriate container. The filtration tower houses the arrangement of neodymium magnets designed to capture the oil.

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Final design sketches were made before ordering final materials.

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The filtration device is automated and controlled with an Arduino Uno microcontroller. The microcontroller is loaded with a code that allows the device to run autonomously with a series of input commands. An actuated peristaltic pump is installed to remove the oil from the filtration tower and transport it into a final container. Actuated solenoid valves are used to control the flow of water and the magnetized oil into the system. These valves are pressure dependent which means that flowrate decreases as the volume in the initial container decreases.

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The initial container is composed of two separate compartments designed for the water and the mixture of oil with ferrofluid. Fluids are initially separated to control flow into the system and simulate an inflow an oil water mixture. Stage 1-3 showcase the filtration system; the tower houses the magnetic arrangement designed to capture the magnetized oil. Two suction tubes are connected to the magnets. When the pump is on, the oil is removed through the suction tubes. After a certain water level is reached, clean water flows out of the filtering tower into a final container.

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The team and I were able to build a functional filtration device capable of removing an average of 89.3% of oil from an oil-water mixture utilizing ferrofluids. It was important to me to make sure the final device was able to be a continuous system, since most current scalable systems require complicated logistics of water transportation. This approach optimizes the volume of filtration to the level initially proposed by our team without the need for interruptions in the process encountered in the initial prototypes. After thorough testing, it was determined that the device was capable of processing 24 ml/min of the water, oil and ferrofluid mixture continuously.

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