Modified Cellulose Acetate Research Articles

Bioinspired Fabrication and Evaluation of Molecularly Imprinted Nanocomposite Membranes with Inorganic/Organic Multilevel Structure for the Selective Separation of Emodin

High purity emodin is in great demand with the development of medical treatment. Molecularly imprinted membranes (MIMs) have gained wide attention for selective separation of emodin due to its preferable selectivity. In this work, we describe a simple two-step method for developing emodin-imprinted TiO2@CA (ETMIMs) and emodin-imprinted SiO2@CA (ESMIMs) based on organic–inorganic nanoparticle (SiO2/TiO2) modified cellulose acetate membranes at room temperature. SiO2/TiO2 is used to improve the structural stability and roughness of membranes, and dopamine is used as the functional monomer and crosslinker. Importantly, the as-prepared membranes not only exhibited enhanced rebinding capacity ([Formula: see text] and [Formula: see text]) but also possessed superior rebinding selectivity (2.76 and 2.99 for physcion and 2.42 and 3.30 for aloe emodin onto ETMIMs and ESMIMs) as well as permselectivity (7.59 and 6.69 for physcion and 5.94 and 5.78 for aloe emodin onto ETMIMs and ESMIMs). The regeneration ability of ETMIMs and ESMIMs still maintained 90.4% and 89.2% of the original rebinding capacity after 10 cycling steps, respectively. The ETMIMs and ESMIMs obtained in this work show potential applications for selective separation and purification of emodin from analogs.

Synthesis, characterization and antibacterial properties of reverse osmosis membranes from cellulose bromoacetate

The antibacterial alkyl bromide groups were introduced into cellulose diacetate (CDA) through the esterification between highly active bromoacetyl bromide and hydroxyl groups under mild conditions and the modified cellulose acetate reverse osmosis membrane (Br-CA-RO) was obtained subsequently after phase inversion process. The results of FTIR and 1H-NMR indicated the existence of alkyl bromide groups in the modified CDA powder. The optical density method was used to confirm its antibacterial ability. The chemical structure and morphology characterization demonstrated that the anchoring of bromoacetyl groups as antibacterial part brought out minimal alteration on membrane chemical structure and its asymmetric structure, but the regularity and density of membranes increased with the degree of esterification. The property testing results showed that the whole physical performance was enhanced with the thermal stability getting slightly worse. Both the flux and salt rejection of Br-CA-RO increased after modification and the latter was close to that of cellulose triacetate RO membrane. The dynamic contact antibacterial testing implied that Br-CA-RO showed much higher antibacterial ability than unmodified RO membranes, and its relative bactericidal rates against E. coli (gram negative) and S. aureus (gram positive) were higher than 73.0% and 93.5%, respectively. This method offers a new approach for antibacterial and functional modification of CA-RO membranes.

Assessment of a Thermally Modified Cellulose Acetate Forward‐Osmosis Membrane Using Response Surface Methodology

AbstractCellulose acetate (CA) flat sheet membranes were fabricated and evaluated in a forward‐osmosis process. Effects of CA concentration, coagulation bath temperature, and annealing thermal treatment on both membrane structure and performance were investigated. NaCl rejection of the optimum membrane was determined utilizing a reverse‐osmosis setup based on conductivity measurements. Two validated models were obtained by means of response surface methodology based on Box‐Behnken design. The optimum operating pressure, temperature, and draw solution concentration were assessed as well.

Electrospun Flexible Cellulose Acetate-Based Separators for Sodium-Ion Batteries with Ultralong Cycle Stability and Excellent Wettability: The Role of Interface Chemical Groups.

Na-ion batteries are one of the best technologies for large-scale applications depending on almost infinite and widespread sodium resources. However, the state-of-the-art separators cannot meet the engineering needs of large-scale sodium-ion batteries to match the intensively investigated electrode materials. Here, a kind of flexible modified cellulose acetate separator (MCA) for sodium-ion batteries was synthesized via the electrospinning process and subsequently optimizing the interface chemical groups by changing acetyl to hydroxyl partly. Upon the rational design, the flexible MCA separator exhibits high chemical stability and excellent wettability (contact angles nearly 0°) in electrolytes (EC/PC, EC/DMC, diglyme, and triglyme). Moreover, the flexible MCA separator shows high onset temperature of degradation (over 250 °C) and excellent thermal stability (no shrinkage at 220 °C). Electrochemical measurements, importantly, show that the Na-ion batteries with flexible MCA separator exhibit ultralong cycle life (93.78%, 10 000 cycles) and high rate capacity (100.1 mAh g-1 at 10 C) in the Na/Na3V2(PO4)3 (NVP) half cell (2.5-4.0 V) and good cycle performance (98.59%, 100 cycles) in the Na/SnS2 half cell (0.01-3 V), respectively. Moreover, the full cell (SnS2/NVP) with flexible MCA separator displays the capacity of 98 mAh g-1 and almost no reduction after 40 cycles at 0.118 A g-1. Thus, this work provides a kind of flexible modified cellulose acetate separator for Na-ion batteries with great potential for practical large-scale applications.

Cellulose acetate fibres surface modified with AlOOH/Cu particles: synthesis, characterization and antimicrobial activity

The AlOOH/Cu modified cellulose acetate fibres were prepared by a facile one-step method. First, the cellulose acetate fibres were treated in an aqueous suspension with the bimetallic Al/Cu nanoparticles, followed by their oxidation. Copper and copper intermetallides do not react with water, while the aluminum does with boehmite formation. During this process AlOOH/Cu particles consisting of boehmite nanosheets self-assembled into flower-like agglomerates, and copper-rich fragments with size of 2 nm were formed. These inclusions could be spread uniformly through the whole volume of nanosheets or form a solid spherical copper-rich core in the center of AlOOH/Cu particles. The AlOOH nanosheets provide an adhesive attachment of the particles on the surface of the cellulose acetate fibres, and the slow migration of copper ions through the shell into the surrounding medium. The morphology, physical and chemical properties of the materials were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, adsorption of nitrogen (BET method), Fourier transform infrared spectroscopy and electrophoretic mobility (ζ-potential measurement). The antibacterial activity of the hybrid fibrous sorbent prepared against Escherichia Coli and Staphylococcus Aureus was studied. Reduction of the concentration viable bacteria reached 100 % after exposure of the bacteria for 1 h to the hybrid fibrous absorbent.

Effect of different molecular weight polyethylene glycol on flat sheet cellulose acetate membranes for evaluating power density performance in pressure retarded osmosis study

In this study, different molecular weights of polyethylene glycol (PEG) (Mw = 4000 and 6000 g/mole) were used as additives for preparations of modified cellulose acetate (CA) flat asymmetric membranes. The effects of additives on membrane characteristics and power density were investigated using the reverse osmosis and pressure retarded osmosis (PRO) methods Membrane characterization and power density of the fabricated membranes were evaluated using the PRO setup. The results show enhancement in the performance of membranes in terms of power density that can be extracted from the membranes with various additives. Furthermore, a comparison was made on the power density obtained using different molecular weights of PEG with CA as a base polymer. A power density of 0.7 W/m2 was obtained from the unmodified CA membrane, which increased to 2.7 W/m2 and 3.1 W/m2 for the modified membranes with PEG 4000 and 6000, respectively. The enhanced power density was due to the better membrane characteristics with respect to its hydrophilicity, pure water flux (PWF), salt rejection and porosity. Therefore, this study provides deeper insights on the performance of membranes with higher molecular weight PEG to get better power density values and attests importance of similar studies in energy science.

Hydrophylicity Enhancement of Modified Cellulose Acetate Membrane to Improve the Membrane Performance in Produced Water Treatment

Produced water is a wastewater generated from petroleum industry with high concentration of pollutants such as Total Dissolved Solid, Organic content, and Oil and grease. Membrane technology has been currently applied for produced water treatment due to its efficiency, compact, mild and clean process. The main problem of produced water using membrane is fouling on the membrane surface which causes on low permeate productivity. This paper is majority focused on the improvement of anti-fouling performance through several modifications to increase CA membrane hydrophilicity. The membrane was prepared by formulating the dope solution consists of 18 wt-% CA polymer, acetone, and PEG additive (3 wt-%, 5 wt-%, and 7 wt-%). The membranes are casted using NIPS method and being irradiated under UV light exposure. The SEM images show that parepared membrane has asymmetric structure consist of dense layer, intermediete layer, and finger-like support layer. The filtration test shows that PEG addition increase the membrane hydrophilicity and the permeate flux increases. UV light exposure on the membrane improves the membrane stability and hydrophilicity. The imrpovement of membrane anti-fouling performance is essential to achieve the higher productivity without lowering its pollutants rejection.

A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

ABSTRACTMany research groups in recent years have demonstrated the importance of obtaining new materials and reducing environmental impact. In this context, the chemical modification of cellulose and its derivatives has received much attention. This study synthesized cellulose acetate gel (CAMDIH) obtained through the modification of cellulose acetate (CA) with a degree of substitution of 2.5, by crosslinking reactions using 4,4′‐diphenylmethane diisocyanate in homogeneous medium. The formation of crosslinks were observed by the presence of Fourier transform infrared spectroscopy absorption bands at 3046 and 864 cm−1, which correspond to the absorption of aromatic groups associated with the incorporation of 4,4′‐diphenylmethane diisocyanate in the CA structure. The potential applications of the gel as a stationary phase were tested using column chromatography in the fractionation and separation of standard solutions of polystyrene and naphthalene. The findings showed the effectiveness of the gel as a stationary state in the separation of mixture compounds. Furthermore, the study found that CAMDHI is an innovative material when considering its simple synthesis and the low costs involved in the process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46063.

Removal of chromium (VI) ions from aqueous solutions using amine-impregnated TiO2 nanoparticles modified cellulose acetate membranes

In this work, TiO2 nanoparticles (NPs) were modified using tetraethylenepentamine (TEPA), ethylenediamine (EDA), and hexamethylenetetramine (HMTA) amines using impregnation process. The prepared amine modified TiO2 samples were explored as an additive to fabricate ultrafiltration membranes with enhanced capacity towards the removal of chromium ions from aqueous solution. Modified membranes were prepared from cellulose acetate (CA) polymer blended with polyethylene glycol (PEG) additive, and amine modified TiO2 by using phase inversion technique. Fourier transform infrared spectroscopy (FTIR), zeta potential (ζ), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), water contact angle (WCA), and atomic absorption spectrophotometer (AAS) studies were done to characterize the membranes in terms of chemical structure, electric charge, thermal stability, morphology, hydrophilicity, and removal performance. The pure water permeability and Cr (VI) ion removal efficiency of the unmodified (i.e. CA/U-Ti) and the amine modified (CA/Ti-HMTA, CA/Ti-EDA, and CA/Ti-TEPA) membranes were dependent on pH and metal ion concentration. Incorporation of amine modified TiO2 composite to the CA polymer was found to improve the fouling and removal characteristics of the membranes during the chromium ultrafiltration process. The maximum removal efficiency result of Cr (VI) ions at pH of 3.5 using CA/Ti-TEPA membrane was 99.8%. The washing/regeneration cycle results in this study described as an essential part for prospect industrial applications of the prepared membranes. The maximum Cr (VI) removal results by using CA/Ti-TEPA membrane for four washing/regeneration cycles are 99.6%, 99.5%, 98.6% and, 96.6%, respectively.

Role of layered materials in emulsified oil/water separation and anti-fouling performance of modified cellulose acetate membranes with hierarchical structure

Membranes with hierarchical architectures consisted of 1D and 2D materials have shown excellent performance in emulsified oil/water separation, but the roles of 2D layered materials in oil/water separation and anti-fouling performance are still to be clarified. Here, we used a facile layer-by-layer assembling approach to fabricate 3D hierarchical membranes using a porous cellulose acetate support membrane coated with graphene oxide (GO) or layered double hydroxides (LDH) grafted with sepiolite (SeP), and then the roles of GO and LDH in oil/water separation and anti-fouling performances of these hierarchically modified membranes were investigated. Results of characterization experiments showed that these membranes were successfully fabricated. Wetting behavior of these membranes indicated that the hierarchical structure can provide high permeate flux and underwater superoleophobic properties. Though the fabrication processes were similar, the surface of SeP + GO and Sep + LDH coated membrane showed different morphologies. After cyclic oil/water separation experiments we found that SeP + GO coated membranes exhibited higher flux and slower decline of permeation than SeP + LDH coated membranes due to its unique properties. Our research demonstrated that the properties of 2D layered materials play important roles in determining water permeability and anti-oil-fouling performance of modified membranes with hierarchical structure.

Ion Transport through Surfactant Modified Cellulose Acetate Phthalate Membrane in Acidic Medium

Cellulose acetate phthalate (CAP)membrane was interacted separately with aqueous HCl solution and aqueous HCl with sodium dodecyl hydrogen sulphate (SDS) as a surfactant and their characteristic properties were determined on the basis of water content, conductance-time and membrane potential data. The possibility of electrochemical modification of cellulose acetate phthalate membrane upon immobilization of the anionic surfactant (SDS) has been also explored. Variable concentration of HCl solutions were used across a cellulose acetate phthalate membrane for membrane potential. The data has been used to interpret the variation of permselectivity ,effective fixed charge density and Donnan distribution ratio of membrane.Int. J. Appl. Sci. Biotechnol. Vol 5(2): 267-272

Exploration of permeability and antifouling performance on modified cellulose acetate ultrafiltration membrane with cellulose nanocrystals

Cellulose nanocrystals (CNCs) were introduced into cellulose diacetate (CDA) matrix via immerged phase-inversion process, aiming to improve the filtration and antifouling performance of CNCs/CDA blending membrane. The effects of CNCs on membrane morphologies, hydrophilicity, permeability and antifouling property were investigated. Results showed that the incorporation of CNCs into CDA membrane could effectively enhance the permeability and antifouling property of CNCs/CDA blending membrane by optimizing membrane microstructure and improving membrane hydrophilicity. A high pure water flux of 173.8L/m2h was achieved for the CNCs/CDA blending membrane at 200KPa, which is 24 times that of the CDA membrane (7.2L/m2h). The bovine serum albumin (BSA) adsorption amount of the CNCs/CDA blending membrane decreased about 48% compared to that of the CDA membrane. Additionally, the CNCs/CDA blending membrane exhibited better antifouling performance with the flux recovery ratio (FRR) of 89.5% after three fouling cycles, compared to 59.7% for the CDA membrane.

Preparation and Characterization of CA−PEG−TiO2 Membranes: Effect of PEG and TiO2 on Morphology, Flux and Fouling Performance

Modified cellulose acetate (CA) membranes were prepared by dissolving the polymers in a mixture of acetone (AC) and N, N dimethylacetamide (DMAc) (70:30) solvent and deionized (DI) water was used in the coagulation bath. The introduction of polyethylene glycol (PEG) additive and TiO2 nanoparticles (NPs) into the casting solution has changed the structures of the resulting membranes during the phase inversion process. Effects of PEG additive and TiO2 NPs on the preparation of the phase-inverted CA ultrafiltration membrane were investigated in terms of morphology, equilibrium water content (EWC), pure water flux (PWF), hydraulic resistance, thermal stability, water contact angle (WCA) and anti-fouling performance. Improvements in average pore size, porosity, thermal stability, and the hydrophilic nature of the CA membranes was detected after the introduction of PEG and TiO2 simultaneously to the polymer matrix. Thermo gravimetric analysis (TGA) results confirmed that the interaction between TiO2 and the degradation temperature of the CA membrane were significantly improved. The anti-fouling performance and the flux recovery potential of the membranes were investigated using the bovine serum albumin (BSA) protein. The M3 (CA-PEG-TiO2) membrane (10.5 Wt. % CA: 4 Wt. % PEG: 2 Wt. % TiO2) exhibited the highest BSA flux result and normalized flux recovery ratios (NFR) for the three fouling cycles.

Fabrication of Potentiometric Cholesterol Biosensor by Crosslinking of Cholesterol Oxidase and Carbon Nanotubes Modified Cellulose Acetate Membrane

Fabrication of Potentiometric Cholesterol Biosensor by Crosslinking of Cholesterol Oxidase and Carbon Nanotubes Modified Cellulose Acetate Membrane

Laccase functionalized cellulose acetate for the removal of toxic combustion products

The ability of Trametes villosa laccase immobilized on cellulose acetate to reduce/eliminate combustions toxicants was investigated using a model enzyme filter design. In the initial stages, various strategies of grafting laccase onto cellulose acetate polymers including partial deacetylated cellulose acetate followed by generation of reactive groups using either periodate or 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO) and the use of different spacer arms [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC); 1,4-butanediol diglycidyl ether (BDGE)] and 3-aminopropyltriethoxysilane was investigated. The best process for effective immobilization of laccase onto both cellulose acetate powders and tows were those involving partial deacetylation, TEMPO activation to generate carboxylic groups, treatment with EDAC as a spacer arm followed by adding the enzyme. This procedure resulted in 45 units/mg laccase activity (28% increase in activity of immobilized enzyme) measured using ABTS as substrate as compared to the other strategies used to immobilize laccase. Further, the immobilized enzyme was able to oxidize >60% of toxicants resorcinol, hydroquinone and methylcatechol passing through the model enzyme filter. This study therefore demonstrates the great possibility of immobilizing laccase onto modified cellulose acetate and the great potential application of immobilized laccase to remove toxicants during combustion.

Lyophilized carbon nanotubes/graphene oxide modified cigarette filter for the effective removal of cadmium and chromium from mainstream smoke

A novel and specific modified cellulose acetate cigarette filter is obtained. The modification includes immersing of the filter into a mixture solution of oxidized multi-wall carbon nanotubes (o-MWNTs) and graphene oxide (GO), followed by lyophilization. During this process, the o-MWNTs/GO composite has been coated on the surface of cellulose acetate in the cigarette filter, with an o-MWNTs:GO:filter weight ratio of 1:1:62. Our experiments illustrated that the modified cigarette filter exhibits favorable adsorption behavior toward heavy metals, which has shown excellent performance for the removal of cadmium and chromium from mainstream smoke. The o-MWNTs/GO modified cigarette filter is demonstrated to be superior to those modified by other moieties, e.g., chitosan, active carbon, o-MWNTs and GO in the removal of heavy metals from mainstream smoke. In addition, it is worth mentioning that the original characteristics of the filter are still maintained. 4mg of the o-MWNTs/GO modified cigarette filter at a length of 25mm is applied for the removal of cadmium and chromium from five brands of cigarettes, giving rise to removal efficiencies of 63–79%.

Preparation of modified cellulose acetate membranes using functionalized multi-walled carbon nanotubes for forward osmosis

Novel modified cellulose acetate (CA) membranes using functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized by phase inversion via immersion precipitation technique. Carboxylated functionalized MWCNTs (F-MWCNTs) were used as additives into the casting solution of CA, 1, 4-dioxane, acetone, lactic acid, and methanol to enhance the forward osmosis (FO) membranes performance. Different contents of F-MWCNTs (0.01, 0.05, and 0.1 wt.%) were added into the casting solution. The novel synthesized CA/F-MWCNTs membranes were characterized by various methods in terms of membranes structure and surface properties, as well as FO performance, and then compared with traditional CA membrane and commercial FO membrane. The surface hydrophilicity, porosity, and tensile strength of CA/F-MWCNTs membranes were improved with the increment of the content of F-MWCNTs in the casting solution. The morphological studies showed that the addition of F-MWCNTs significantly changed the surface properties of the modified CA membranes. The FO performance was evaluated using purified water as feed solution and 1M NaCl solution as draw solution. The CA/F-MWCNTs membranes showed higher water permeability and salt rejection in the range of 0.01–0.1 wt.% F-MWCNTs content than CA membrane and the commercial FO membrane. These encouraging results suggested that CA/F-MWCNTs membranes showed superior potential to be further developed for FO applications.

Preparation, Characterization and Properties of Cellulose Acetate-Grafted-Poly(glycidyl methacrylate) Copolymers

The cellulose acetate-grafted-poly(glycidyl methacrylate) copolymers were synthesized successfully by free radical polymerization. The resulting copolymer was characterized by proton nuclear magnetic resonance (1H-NMR), solid-state 13C-NMR, Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The crystallization behavior, thermal properties, specific particle surface area, moisture sorption behavior of the modified cellulose acetate were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) method and Dynamic Vapor Sorption (DVS) instrument. It was found that the poly(glycidyl methacrylate) (PGMA) grafting was effective in improving the water adsorption of cellulose acetate (CA) changing the specific surface area, and reducing the Tg of copolymers.

Preparation and Characteristics of Novel Fibers Based on Cellulose Acetate and Soy Lecithin for Attracting and Binding POPs

Soy lecithin (SL)-modified cellulose acetate (L-CA) fibers for use as a novel biomimic material were prepared by a dry-jet wet spinning process from a solution of the polymer in dioxin. Characteristics of the L-CA fibers, such as structural properties, water absorbance, electrical conductivity and accumulation of trace persistent organic pollutants (POPs), were examined. Cross-sectional scanning electron microscopy (SEM) of L-CA unveiled a finger-like structure, along with a thin dense surface layer like that of CA. On the basis of X-ray photoelectron spectroscopic (XPS) observations, it was concluded that the enhancement of binding energy was optimum with 10% SL in the fiber, whereas superfluous SL led to self-assembly between the SL molecules, which weakened the binding between the SL and CA. Also, the L-CA fibers showed good water absorbance and a low charge conductivity in comparison to that of the non-modified CA fibers. Examination of the ability to accumulate POPs from water showed that L-CA is a effective candidate for the removal of micropollutants from aqueous solution.

Study of Mixed Membrane Potential with Surface Modified Cellulose Acetate Nanofilter

:Cellulose acetate (CA) membranes prepared by wet phase inversion technique were subjected to deposition of multilayer of Cu2 [Fe (CN)6] of different molar concentration (0.1m, 0.01m, 0.001m) by using the solution of potassium ferro cyanide and copper sulphate on the surface of CA membrane by alternate changing the two solutions in a special glass cell. This surface modification converted the CA membrane into nanofilters of more gelatinous texture and exact semipermeability. Electrochemical characterization of nanofilters has been attempted by calculating the values of transport number, fixed charge density and permselectivity using the data of mixed membrane potential across normal and surface modified membranes with electrolytic solutions of NaCl and KCl. The results showed that the presence of additional electrolyte, even of the same concentration on the both sides of membrane, significantly influences electrochemical character of nanofilter. Scanning electron microscopy (SEM) of the prepared nanofilter showed the resembling morphology and nanoporous surface texture of nanofilters with the deposition of multi electrolytic layers. The study successfully demonstrated the effect of simultaneous multi-ion transport across the nanofilters to pave mile stone of its applicability in selective recognition and filtration aspects.