Nature identification and morphology characterization of cation-exchange membrane fouling during conventional electrodialysis

Abstract

The aim of this work was to study the effect of a concentrate solution pH value and of the composition in calcium, carbonate, and protein of a diluate solution to be treated by conventional electrodialysis on the fouling of cation-exchange membranes (CEM). It appeared that after demineralization of solutions containing CaCl(2) and CaCl(2)+Na(2)CO(3) using a concentrate solution maintained at a pH of 12, mineral fouling appeared on both sides of the CEM. The nature of the deposits was identified as calcium hydroxide and/or carbonate on both surfaces. The mineral fouling presented an aggregation-like crystal following a carnation-like pattern of aggregates of small rhombohedral crystals with CaCl(2) added alone, while CaCl(2)+Na(2)CO(3) yielded a smoother spherical crystal. Protein fouling was detected only on the CEM surface in contact with the diluate after demineralization of a solution containing CaCl(2)+Na(2)CO(3) using a concentrate pH value of 2.

Nature identification and morphology characterization of anion-exchange membrane fouling during conventional electrodialysis

“…This study was the complement to a previous work on CEM [10], where a deposit, presumably of a protein nature, was found on certain CEM, as well as mineral fouling composed of calcium carbonate and/or hydroxide. Our objectives in the present work were to identify the nature and to characterize the morphology of AEM fouling during conventional electrodialysis demineralization of a whey protein isolate solution with different compositions in calcium and carbonate, using different pH conditions of the concentrate solution.…”

“…The thickness of the membrane was measured using a Mitutoyo Corp. IDC type digimatic indicator with absolute encoder (Model ID-C112 EB, Kanagawa-Ken, Japan), according to Ayala-Bribiesca et al [10].…”

“…The membrane electrical conductivity was calculated from the measured membrane thickness and its electrical resistance, obtained from membrane conductance, following the same method as in a previous study on CEM [10], using a specially designed cell (conductivity clip) (Laboratoire des Matéri-aux Echangeurs d'Ions, Créteil, France) and a YSI conductivity meter (Model 35, Yellow Springs Instrument Co., Yellow Springs, OH).…”

“…Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra of the AEM surface in contact with the diluate were taken with a Nicolet 560 FTIR spectrometer (Nicolet Instrument Corp., Madison, WI, USA) covering the complete surface of the zinc selenide ATR crystal (Nicolet Instrument Corp.), according to the procedure of Ayala-Bribiesca et al followed for CEM [10]. To confirm or discard the presence of a protein fouling layer, spectra were processed and analyzed using Omnic 5.1a software (Nicolet Instrument Corp.) according to the criteria previously described [10].…”

Application of electrodialysis to extract 5′-ribonucleotides from hydrolysate: efficient decolorization and membrane fouling

“…19,20 Generally, anion exchange membranes are more sensitive and susceptible to fouling during the ED process. 21,22 Nevertheless, mechanical cleaning and treatment with dilute bases and acids can generally restore the original properties of the membranes. In contrast, the fouling of membranes by organic anions is more severe because they are small enough to penetrate into the membrane and stay inside the membrane phase due to their low mobility.…”