Agitators and Mixers in Transesterification

Transesterification is a cornerstone process in biodiesel production, involving the conversion of triglycerides (like vegetable oil or animal fat) into esters (biodiesel) and glycerol using an alcohol (typically methanol) and a catalyst. Effective mixing during this reaction is crucial, and that’s where agitators and mixers come in.

Role of Agitators/Mixers in Transesterification

  • Enhanced Reaction Rate: Proper mixing ensures that reactants are in close proximity, leading to faster reaction rates.
  • Uniform Heat Distribution: Even mixing helps in uniform heat distribution, ensuring that the reaction takes place consistently throughout the reactor.
  • Improved Yield: Thorough mixing can increase the yield of biodiesel by ensuring maximum contact between the reactants.
  • Minimized Side Reactions: Effective mixing reduces the chances of undesirable side reactions, such as soap formation.

Types of Agitators/Mixers for Transesterification

  • Paddle Mixers: These are simple and effective for mixing in batch processes. They help in achieving a homogenous mixture but may not be the best for very viscous mixtures.
  • Turbine Agitators: With multiple blades set at different angles, these agitators ensure thorough mixing and are commonly used in biodiesel production.
  • Propeller Agitators: These resemble boat or airplane propellers and are effective for mixing less viscous liquids at higher speeds.
  • Anchor Agitators: Ideal for high-viscosity mixtures, these have a sweeping action that ensures thorough mixing.
  • Helical Mixers: These are designed to move the material in a specific direction, ensuring uniform mixing and minimizing dead zones in the reactor.

Considerations for Effective Mixing in Transesterification

  • Viscosity: The viscosity of the reactants can influence the choice of mixer. More viscous mixtures might require stronger, anchor-style mixers.
  • Scale of Operation: Large-scale operations might require more powerful or multiple agitators to ensure thorough mixing.
  • Reactor Design: The design of the reactor vessel itself can influence the efficiency of mixing. Some reactors are designed with internal baffles or specific shapes to optimize mixing.
  • Reaction Speed: If the transesterification is expected to proceed very rapidly, the mixing apparatus needs to keep up to ensure uniformity.
  • Energy Consumption: Agitators consume energy, so their efficiency can influence the overall energy costs of biodiesel production.


In the transesterification process, the role of agitators and mixers is pivotal. They ensure that the reaction proceeds efficiently, uniformly, and yields a high-quality biodiesel product. The choice of mixer, its design, and operational parameters should be made considering the specific needs of the biodiesel production process in question.