Permeability through cellulose membranes grafted with vinyl monomers in a homogeneous system. VII. Acrylamide grafted cellulose membranes

Abstract

SynopsisThe homogeneous grafting of acrylamide ( AAm) onto cellulose was carried out in a dimethyl sulfoxide/paraformaldehyde (DMSO/PF) solvent system. The diffusive permeabilities of solutes through the AAm-grafted cellulose membranes, apparent activation energy for solute permeation through them, states of water in them, and their microphase separated structures were investigated. The permeability through the grafted membranes was superior to that through the cellulose membrane cast from the DMSO/PF solution of cellulose. The total water contents of the grafted membranes were larger than that of the cellulose membrane. The state of intermediate water in the grafted membranes with fine microphase separated structures was influenced remarkably. A higher activation energy was observed for the solutes with poor permeability through the membranes. INTRODUCTIONIt is known that different states of water are present in water-swollen membrane~.'-'~ The amount of each state of water in membranes varies with the affinity of membrane substrates for water. In a series of studies,16-'l we have investigated the relationship between the diffusive permeabilities of solutes through membranes and the amount of each state of water in them to clarify the mechanism of membrane permselectivity. Cellulose grafted with vinyl monomers in a homogeneous solution system has been used as membrane materials. The kind of monomers and composition of copolymers were varied to prepare the membranes of different affinity for water. The change in the states of water in the grafted membranes brought about changes in the permeabilities of solutes through them.In this paper, we chose a hydrophilic vinyl monomer, acrylamide ( AAm) .It is expected that the affinity of the membranes for water would increase. The permeabilities of solutes through the AAm-grafted cellulose membranes are investigated in relation to the composition of copolymers, microphase separated structures of the membranes, and states of water in them. EXPERIMENTAL Grafting and Membrane PreparationThe homogeneous grafting of AAm onto cellulose in a dimethyl sulfoxide! paraformaldehyde (DMSO/ PF ) solvent system and the characterization of * To whom correspondence should be addressed. The crude grafted mixtures were cast at room temperature on glass plates and dried at about 60°C under reduced pressure for 24 h. After being immersed in water for several days, the membranes were easily peeled off. All membranes were stored in distilled water until use.16 Diffusive PermeabilityThe diffusive permeability P was measured a t temperatures from 20.0 to 50.0"C by the method described in the previous paper.16 Ten solutes of different molecular weights were used. The values of Mu of commercial poly (ethylene glycol) ( P E G ) samples were estimated from [a] obtained with benzene atThe PEG samples were abbreviated as PEG-IV, PEG-VI, and PEG-XX in the order of increasing molecular weight. Hydraulic PermeabilityThe flux of water under an applied pressure of 10 kg cm-2 was measured with a reverse os...

Impact of functional groups on cellulose nanofibers on the state of water molecules, photocatalytic water splitting, and photothermal water evaporation

“…7 Furthermore, grafting acrylamide or methyl acrylate onto cellulose augments cellulose's affinity for water, consequently impacting the composition of IW within the membrane. 8,9…”

“…Moreover, the state of water molecules within cellulose can be intentionally modied through the graing of small molecules and the application of diverse preparation methodologies. [7][8][9] Recent research ndings substantiate that the introduction of acrylonitrile onto cellulose leads to a signicant reduction in the quantity of IW. 7 Furthermore, graing acrylamide or methyl acrylate onto cellulose augments cellulose's affinity for water, consequently impacting the composition of IW within the membrane.…”

“…7 Furthermore, graing acrylamide or methyl acrylate onto cellulose augments cellulose's affinity for water, consequently impacting the composition of IW within the membrane. 8,9 In pursuit of harnessing the power of solar energy and water, two of Earth's most abundant resources, photocatalytic water splitting (PWS) and photothermal water evaporation (PWE) emerge as promising avenues for hydrogen (H 2 ) and fresh water production, 10 respectively. Hydrogen gas, recognized for its carbon-free, renewable, and sustainable attributes, stands as the quintessential energy carrier.…”