Izabela Kowalska

Separation of anionic surfactants on ultrafiltration membranes

Abstract The objective of this study was to investigate the influence of MWCO, pressure, SDS concentration, salt amount and temperature on surfactant removal and permeate flux. Intersep Nadir membranes made from polyethersulphone (PES) and polysulphone (PS) were used. With the addition of a mineral salt to the SDS solution, a dramatic decrease in retention of SDS was observed. There was no discernible effect on the retention coefficient of the membranes with the increase in the amount of the mineral salt added to the SDS solution. The volume flux was slightly dependent on the ionic concentration in the feed solution: high ion concentration caused a small decrease of the water flux. The effect of pressure on the separation efficiency for the PES and PS membranes was evaluated; it produced only a small reduction in the retention as the pressure was increased. With the increase of temperature of SDS solutions, a decrease in the retention of SDS was observed. The permeate flux increased with temperature due to the solution viscosity decrease.

Dead-end and cross-flow ultrafiltration of ionic and non-ionic surfactants

Abstract Different molecular weight cut-offs (MWCO = 2–30 kDa) flat sheet membranes and hollow fibre modules were applied for filtration of surfactant aqueous solutions (Triton QS-44, CTAB and Triton X-100). The experiments were performed in a stirred cell (dead-end regime) and in a semi-pilot membrane installation (cross-flow regime). The effect of the process conditions (transmembrane pressure and cross-flow velocity) and the interaction between the membranes’ polymer and surfactants under a wide range of concentrations on ultrafiltration effectiveness was evaluated. The results demonstrated that the highest retention coefficient of anionic and cationic surfactants was obtained with the hydrophobic membranes; however, hydrophilic membranes were characterised by distinctly higher retention of the non-ionic surfactant. It was proved that with a good adjustment it is possible to determine, with the help of a linear dependence, the concentration of a surfactant in the permeate depending on the concentration...

An assessment of the cleaning solutions’ purification by membrane filtration

Abstract The results of the purification of contaminated cleaning solutions (a single-phase detergent) emanating from a diary industry were reported. Flat-sheet ultrafiltration (UF) and nanofiltration (NF) membranes that differed in their molecular weight cut-offs were evaluated for their potential use in the recovery of cleaning solutions. The experiments were performed in a stirred cell operating in a dead-end filtration mode. The membranes were tested under different transmembrane pressures (0.5–4 bar), mainly for the purpose of: (i) a long-term evaluation of membrane hydraulic performance, (ii) an assessment of fouling tendency, (iii) an evaluation of the quality of the recovered solution in comparison with the fresh detergent, and (iv) an assessment of the chemical stability of a polymer material. Studies have demonstrated the usefulness of membrane filtration using polymeric membranes for the recovery of a single-phase detergent for the purpose of its reuse in cleaning systems. The recovered deterge...

Concentration of contaminated single-phase detergents by means of unit and integrated membrane processes

ABSTRACT Unit and integrated pressure-driven membrane processes were investigated in a semi-pilot scale for the purification and concentration of contaminated cleaning solutions. For the tests, liquid acidic and alkaline single-phase detergents tailor-made for CIP systems in the dairy industry were selected. The effect of the permeate recovery rate on the quality of recovered solutions was evaluated. Integrated purification processes provided a very high separation of the milk components with a slight weakening of the detergency properties of the permeate. The least effective integrated treatment option (PM5+AFC30) enabled 100% retention of proteins, and over 98% retention of low molecular weight lactose.