Recovery of proteins and other biological compounds using fibrous materials: II. Flocculation by polyelectrolyte addition

Abstract

Polyelectrolytes have been used in wastewater treatment processes to destabilize colloidal suspensions of proteins, cells and other biological compounds, resulting in¯occulation. When a solution containing a single model protein, bovine serum albumin (BSA), is treated with a polyelectrolyte, carboxymethyl cellulose (CMC), large and strong¯ocs are formed, which are easily retained by a 20 mm pore size ®lter. However, when a mixture of proteins, cells, and fats from an actual wastewater sample is treated in the same manner, smaller and weaker¯ocs are observed. An adsorption and ®ltration process for the recovery of valuable biological compounds using cellulosebased ®brous materials has been developed. When used simultaneously with CMC, cellulose acetate and triacetate ®brets (CAF and CTF) resulted in high recovery of biomolecules from solution at very low dosages of both polyelectrolyte and ®brets. CMC interacts with biomolecules by electrostatic interactions and polymer bridging, while CTF/CAF facilitate¯oc growth by adsorption and bridging of primary particles and by entrapment of small aggregates within their highly ®brillated microstructure.

Recovery of proteins and other biological compounds using fibrous materials: I. Adsorption by salt addition

“…Also, the CTF dosages required for a satisfactory protein removal in this case may not be economically feasible. Further studies using polyelectrolytes together with ®brets resulted in promising features in terms of dosages, 10,11,13 operating conditions, and initial cost estimation 11 …”

Structural Evolution of an Interpolyelectrolyte Complex of Charged Dendrimers Interacting with Poly(l-glutamate)

“…Interpolyelectrolyte complex (PEC) formation in aqueous solutions is widely used for separation processes (by flocculation or coacervation), for enzyme/drug immobilization 3 and stabilization by physisorption into complex coacervates, hydrogels, or microcapsules, , and for controlled drug release from pH-, − temperature-, or irradiation-sensitive “smart” hydrogels and capsule membranes . Many of the applications require control (or proper choice) of the strength of the binding interaction, which is governed by the electrostatic energy of the correlated charge patches of the polyion (polyampholyte), , in addition to hydrophobic and specific free energies (e.g., hydrogen-bonding). , The complex formation among weak polyelectrolytes is thus restricted to a pH range where the dissociation makes a “critical” minimum charge density be exceeded, which increases with the hydrophilicity of the polyion backbone and with the screening of the charges by a higher ionic strength.…”