Cleaning of Colloidal Contamination

Introduction

Most colloidal particles are surface-charged, making them prone to accumulation on the membrane surface or within membrane pores. After a period of accumulation, colloidal particles will form a so-called filter cake layer on the membrane surface, which affects the permeation quality and membrane life. The figure below demonstrates a transient electrokinetic model to predict the permeate flux and the observed repulsion of NF membranes in the presence of colloidal particles.^[2]

Fig.1 Schematic diagram of transient electrodynamic model.^[2]

Our Services

Ultrasonic Cleaning

Our ultrasonic technology mainly utilizes the simultaneous effects of acoustic cavitation to inactivate and decompose pathogenic microorganisms and organic fouling. Ultrasonic irradiation can destroy the concentration polarization and filter cake layer on the membrane surface, resulting in an increase in flux. We are committed to improving the performance of membrane filtration processes, helping customers save on costs by reducing the number of membranes (or total membrane area) required.

Membrane Surface Modification

Alfa Chemistry starts from improving the adhesion between colloid and membrane, and realizes the process of inhibiting or reducing colloid pollution through surface membrane modification. Based on the influence of surface film properties such as surface hydrophilicity, charge, and roughness on the fouling process, we have developed several modification directions, such as hydrophilization, smoothing, and introduction of charged/bactericide groups on the film surface. The specific modification techniques we employ include photo-initiated grafting of hydrophilic monomers, physical coating of water-soluble polymers or surfactants, plasma-induced grafting, chemical vapor deposition, etc.

Fig.2 Schematic diagram of a photo-induced living graft polymerization on a membrane surface.^[4]

References

1. Choi Y J, et al. Application of ultrasound to mitigate calcium sulfate scaling and colloidal fouling. Desalination. 2014, 336:153-159.
2. Mamun M, et al. Colloidal fouling of nanofiltration membranes: A novel transient electrokinetic model and experimental study. Chemical Engineering Science. 2015.
3. Victor Kochkodan, et al. Polymeric membranes: Surface modification for minimizing (bio)colloidal fouling. Advances in Colloid and Interface Science. 2014.
4. Ma H, et al. A Novel sequential photoinduced living graft polymerization. Macromolecules. 2011, 33(2):331-335.

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