Synthesis, Characterization, and Evaluation of Evaporated Casting MWCNT/Chitosan Composite Membranes for Water Desalination

Abstract

Fresh water scarcity and pollution turn out to be a most serious issue throughout the world due to the rapid population growth. The application of nanomaterials (NMs) for the removal of pollutants from water has attracted significant attention. The nanofiltration membrane was fabricated through the evaporative casting (EC) method using multiwalled carbon nanotubes (MWCNT) and chitosan (CHIT) as the surfactant to enable water purification. The developed EC membrane properties were characterized in mechanical, surface charging (zeta potential), surface morphology, and hydrophobicity properties. Results demonstrated that incorporation of MWCNT and the biopolymers (chitosan) resulted in suitable developments in mechanical properties of the membrane. For example, the membrane has shown values for tensile strength (28 ± 1 MPa), elongation (10.2 ± 1.2%), Young’s modulus (1.2 ± 0.1 GPa), and toughness of (1.9 ± 0.2 J/g). When more significant changes were investigated on the surface morphology of the EC membrane, it was observed that the pores on the surface morphology of the EC membrane decreased as the evaporative casting method was used. Moreover, the permeability of the membrane towards water, inorganic salts, and pH effect on salt rejections was studied using the NF/RO system. These established nanocomposite membranes signify the promising candidates for fresh water desalination and elimination of organic impurities.

Carbon Nanotube Membranes in Water Treatment Applications

“…The resulting membrane showed enhanced mechanical properties due to the presence of CNTs and provided a simultaneous increase in flux and salt rejection capacity, which was attributed to the packing of hydrophilic chains in the matrix and the presence of internal nanochannels formed by the CNTs. [ 121 ] Another desalination alternative was developed by Noy and co‐workers, who inserted short segments of CNTs into lipid bilayers to form TFC membranes that simulated biological water channels. [ 122 ] The desalination efficiency was tested by measuring water and chloride ion transport by fluorescence‐based assays.…”

Recent Advances in Applications of Carbon Nanotubes for Desalination: A Review

“…Because structural integrity will reduce due to the large gap caused by the low load of CNTs [162]. In addition, the mechanical property will be strengthened with the incorporation of MWCNT in chitosan composite membranes [163]. The main reason is that the addition of MWCNTS can significantly improve the crystallinity and tensile strength of chitosan in composite membranes [163].…”

“…The mechanical performance of composited CNT membranes will also be enhanced as CNTs are introduced [ 158 , 159 , 160 , 161 , 162 , 163 ]. Carbon nanotubes can function well as appropriate support [ 158 ].…”

“…In addition, the mechanical property will be strengthened with the incorporation of MWCNT in chitosan composite membranes [ 163 ]. The main reason is that the addition of MWCNTS can significantly improve the crystallinity and tensile strength of chitosan in composite membranes [ 163 ]. Moreover, the CNT interlayer can absorb [ 165 ] and store the aqueous amino solutions to promote the interfacial polymerization and provide robust mechanical support [ 166 , 167 ] for the NF of the thin skin layer on a microporous substrate ( Figure 6 b) [ 103 ].…”

Preparation and Characterization of Modified Polysulfone with Crosslinked Chitosan–Glutaraldehyde MWCNT Nanofiltration Membranes, and Evaluation of Their Capability for Salt Rejection

“…Dumée et al [28] produced a self-supporting membrane with 99 percent salt rejection and a mass flow of 12 kg/m 2 h. Additionally, CNTs can be distributed in suitable solvents using a sonicator to create composite membranes with high transport rates and large-scale nanotube applications. Using carbon nanotubes, several experiments were conducted to improve the mass transfer rate of polymer membranes [27,[29][30][31][32][33]. In addition, to avoid the aggregation of CNT particles and enhance the interaction between the graphitic surface of the nanomaterial wall and the polymeric matrix, carbon nanotubes were functionalized.…”