(550e) Organic Solvent Membrane Filtration: Rational Design of Bottlebrush Membranes

Our long-term goal is to fractionate crude-oil mixtures and challenge phase-change distillation with low energy non-phase change membrane filtration using graft chemistry and transport phenomena. We have developed and tested a new series of bottle-brush filtration membranes that have flexibility in chemistry, structure and morphology (these properties are not available in current commercial membranes) and are stable in organic solvents. So far we have tested them with a series of alcohols and the dye Rose Bengal (Ramesh et al. (2021) “Organic solvent filtration by brush membranes: Permeability, selectivity and fouling correlate with degree of SET-LRP grafting”, J. Membr. Sci.618, 118699). The permeability of these composite membranes, evaluated with 6 organic solvents (alcohols), correlates with solvent properties and can be tailored with degree of grafting (DG). Filtration performance was assessed by measuring the selectivity and fouling of the organic dye Rose Bengal (RB) in ethanol. The polarized wall concentration increased with DG, whereas the RB sieving coefficient decreased with DG. Flux decline during RB filtration was best described by pore blocking and by heterogeneous and Langmuir sorption models. These studies provide a basis for designing polymeric membranes comprising branched brush selective layers with defined microstructure not possible with the widely popular phase inversion process. Our latest unpublished results demonstrate that these membranes can be tuned to distinguish between n-butanol and iso-butanol and between iso-propanol and n-butanol, so we are hopeful that they will also be able to fractionate light crude oil and eventually crude-oil.