Preparation of cellulose-rich membranes from wood: effect of wood pretreatment process on membrane performance

Abstract

In this study cellulose-rich membranes were fabricated from untreated and treated hardwood biomass solutions in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc])—dimetylsulfoxide (DMSO) system via wet phase separation. Wood treatment methods aimed to get purified cellulose fraction of wood. Treatment sequence was as followed: deep eutectic solvent pretreatment, sodium chlorite bleaching, and alkaline treatment. Resulted biomass after each treatment step was characterized by chemical composition and crystalline fraction content. Flat-sheet membranes were produced from biomass samples after each treatment step. Characterization of membranes included measurements of pure water permeability and (poly)ethyleneglycol 35 kDa retention, Fourier-transform infrared and Raman spectroscopy, X-ray diffraction measurements and thermogravimetric analysis. The study revealed that it was possible to fabricate membrane from untreated wood as well as from wood biomass after each of treatment steps. The resulted membranes differed in chemical composition and filtration performance. Membrane prepared directly from untreated wood had the highest permeability, the lowest retention; and the most complex chemical composition among others. As treatment steps removed lignin and hemicelluloses from the wood biomass, the corresponding membranes became chemically more homogeneous and showed increased retention and decreased permeability values.

Green and Non‐Conventional Materials for Membrane Synthesis: A Review

“…Cellulose Acetate has also been recovered from waste cigarette filters which is one of the most abundant forms of plastic waste present globally. Typically, biomass has 40 to 60 % cellulose, 15 to 30 % hemicellulose, and 10 to 25 % lignin [8] . From Figure 3 it can be confirmed that cellulose has hydroxyl groups, which are responsible for its high hydrophilicity.…”

“…The properties of lignin and the complexity of the chemical composition of the wood prevented the formation of a dense top layer. [8] After the removal of lignin and hemicellulose, the wood membrane becomes flexible, with greater hydrophilicity and oleophobicity. [10] With further treatments, the purity of cellulose increased producing a chemically more homogeneous, tighter membrane having increased retention and decreased permeance.…”

“…Membranes manufactured from untreated birch wood exhibited higher permeance and lower retention. The properties of lignin and the complexity of the chemical composition of the wood prevented the formation of a dense top layer [8] …”

“…After the removal of lignin and hemicellulose, the wood membrane becomes flexible, with greater hydrophilicity and oleophobicity [10] . With further treatments, the purity of cellulose increased producing a chemically more homogeneous, tighter membrane having increased retention and decreased permeance [8] . More research is required for solvents used to treat substrates.…”

Wood-Based Cellulose-Rich Ultrafiltration Membranes: Alkaline Coagulation Bath Introduction and Investigation of Its Effect over Membranes’ Performance

“…Despite the chosen method of describing cellulose as a polymer-regardless of whether it is recognised as hydrophilic or an amphiphilic one [5][6][7][8][9]-the regenerated cellulose membranes are universally acknowledged as very hydrophilic, having higher biocompatibility and lower fouling tendency when compared with petroleum-based polymers due to cellulose being a biopolymer [10][11][12][13]. The existing research focusing on the manufacturing of cellulose membranes is highly variable regarding whether research groups prefer to use commercially produced cellulose [14][15][16] or biobased cellulose sources [2,17,18], using various solvents with high capacity for cellulose dissolution [3,4,19]. The steady interest towards ionic liquids (ILs) as cellulose and biomass solvent media is supported with such characteristics as their potential recyclability, low vapour pressure, and good chemical and thermal stability [20][21][22][23].…”