Synthesis of polyaluminum chloride with a membrane reactor: process characteristics and membrane fouling

Polyaluminum chloride was synthesized with a membrane reactor, in which NaOH was added into AlCl3 solution through the membrane's micropores to reduce the NaOH droplets size. The content of the most efficient species increased to about 80%. The process characteristics in the reaction (i.e., flow velocity, pressure drop), and membrane fouling and cleaning were investigated. The evolution of both flow velocity and pressure drop during the reaction were related to changes in species distribution and solution viscosity. The process characteristics were well interpreted in terms of the Bernoulli equation. After reaction, the membranes were recovered by cleaning with diluted hydrochloride acid. This study is crucial for process design and scale-up of membrane reactors.