Synthesis of polytriethanolamine based surfactant and its flotation performance evaluation of oilfield produced water treatment

As the amount of oilfield produced water (PW) keeps going up, highly efficient flotation agent is needed. In this paper, a series of surfactants (abbreviated as Q-PTEA-Cn) derived from polytriethanolamine were synthesized. Their surface activities and flotation performance were evaluated. The result showed that the Q-PTEA-Cns can effectively reduce the surface tension of water and interface tension of crude oil/water. The Q-PTEA-C12-1 had the best flotation performance and the rational flotation condition was recommended as follows: Q-PTEA-C12-1 dosage 100 mg/L, gas flow 3 L/min, and flotation time 20 minutes. At this condition, the oil removal efficiency of two commonly used flotation agents (FL-1 and FL-2) and Q-PTEA-C12-1 were 62.3%, 69.1%, and 83.6%, respectively. The flotation kinetic of Q-PTEA-C12-1 can be described by Maruyama’s flotation model, which presented that there was adsorption of oil droplet adsorbed surfactant onto bubble. Floatation mechanism study confirmed that the Q-PTEA-C12-1 can absorb onto the oil droplet and showed that the Q-PTEA-C12-1 can enhance the bubble–drop attachment efficiency and the stability of bubble–drop agglomerates.