Fractionation and concentration of lignosulphonates by ultrafiltration

Studies on ultrafiltration of spent sulfite liquor using various membranes for the recovery of lignosulphonates

“…UF, a pressure-driven rate governed membrane separation process in which components of a mixture are separated by preferential transport of solutes through membrane, has been used to separate spent liquor into purified fractions of lignosulphonates and sugars [3--6]. RO has also been extensively used for concentration ofsulfite liquor and bleach plant effluent [6][7][8][9]. A combination of UF and continuous diafiltration has been used to purify lignosulphonates [ 10,11 ].…”

Reversible adsorption inside pores of ultrafiltration membranes

“…It has been possible in some cases [7,8] to describe the rejection of polymer molecules using the theory of reverse osmosis/nano-filtration separation, originally developed for small molecules [9,10]. However, this approach does not explain the deviations of the filtration velocity, found in the ultrafiltration experiments reported here.…”

Solute rejection in the presence of a deposited layer during ultrafiltration

“…The observed rejection showed a characteristic maximum in the rejection as a result of the decrease in rejection at higher fluxes due to concentration polarization [ 19]. The permeate was collected in four separate streams (see Method): the rejections for positions 2-4 were similar, however higher rejections were measured at the first position in the flux region where concentration polarization becomes important.…”