Analysis of membrane fouling by Brunauer-Emmett-Teller nitrogen adsorption/desorption technique

Abstract

Membrane fouling is the major factor limiting the wider applicability of the membrane-based technologies in water treatment and in separation and purification processes of biorefineries, pulp and paper industry, food industry and other sectors. Endeavors to prevent and minimize fouling requires a deep understanding on the fouling mechanisms and their relative effects. In this study, Brunauer-Emmett-Teller (BET) nitrogen adsorption/desorption technique was applied to get an insight into pore-level membrane fouling phenomena occurring in ultrafiltration of wood-based streams. The fouling of commercial polysulfone and polyethersulfone membranes by black liquor, thermomechanical pulping process water and pressurized hot-water extract was investigated with BET analysis, infrared spectroscopy, contact angle analysis and pure water permeability measurements. Particular emphasis was paid to the applicability of BET for membrane fouling characterization. The formation of a fouling layer was detected as an increase in cumulative pore volumes and pore areas in the meso-pores region. Pore blocking was seen as disappearance of meso-pores and micro-pores. The results indicate that the presented approach of using BET analysis combined with IR spectroscopy can provide complementary information revealing both the structure of fouling layer and the chemical nature of foulants.

One-step synthesis of nitrogen-grafted copper-gallic acid for enhanced methylene blue removal

“…Compared to the non-grafted CuGA (surface area of 198 m 2 /g, pore volume of 0.4 cc/g, and average pore diameter of 8.6 nm) 22 , the N g -CuGA possess a larger pore size. This phenomenon might be occurred due to the incorporation of small-grafting molecules (i.e., Gly), which may strain the internal pores of CuGA, and eventually caused a significant reduction in the surface area of N g -CuGA 24 , 46 . Although incorporating Gly is shown to trigger pore blockage, it is postulated that the nitrogen groups from the grafted molecules may act as the additional adsorption sites 24 , which can promote the adsorption capacity of CuGA.…”

Co-Immobilization and Compartmentalization of Cholesterol Oxidase, Glucose Oxidase and Horseradish Peroxidase for Improved Thermal and H2o2 Stability

“…We also observed a lower ABTS conversion in LbL systems compared to when ultrafiltration membranes were used as support, which shows that the type of support material strictly affects the properties of the fabricated biosystems [42]. PDLG electrospun material has a higher pore size than the UFX5 membrane [43,77], which means that an easier elution of biomolecules should be expected, especially for HRP directly adsorbed on the support. The larger pores in the support might be able to decrease substrate conversion efficiency due to the fact that enzymes immobilized have less time to act on the ABTS when the flow is higher.…”

Membranas Poliméricas

“…Já a isoterma BET tipo II é observada em polímeros vítreos cujas moléculas de penetrante apresentam elevada afinidade química. 48 Graficamente, a isoterma BET tipo II é uma combinação das etapas iniciais de uma isoterma de sorção em modo duplo com a isoterma BET tipo III (Figura 7.12d). Em termos estruturais, a sorção ocorre de modo similar ao observado na sorção em modo duplo.…”