Surface functionalization of nylon 66 membrane using para-phenylenediamine and carboxylic functionalized multi-walled carbon nanotubes for removal of calcium ions from aqueous solution

Abstract

Nylon 66, which is an important membrane class used in manufacturing of chitin and chitosan, have a number of features that can be improved by surface functionalizations into a novel composite structure with support of ultrasound and silica gel (SiG) catalyst in a doubled amidation reaction. Firstly, nylon 66/para-phenylenediamine thin film composite (NP-TFC) is prepared from commercial nylon 66 membrane in an ultrasound assisted hydrolysis-amidation reaction. Secondly, carboxylic functionalized multi-walled carbon nanotubes (MWCNT-COOH) are grafted on the NP fiber in an ultrasound assisted/SiG-catalyzed amidation reaction, where para-phenylenediamine (pPD) role is cross-linking. As an excellent result confirmed by either Fourier transform infrared (FTIR), Raman spectrometry or scanning electron microscopic (SEM), bundled MWCNTs bridges are easily built in SiG-catalyzed ethanol media to connect nylon 66 fibers at distances of 0.3-1 lm. The vacuum filtration test confirmed that as-prepared nylon 66/pPD/MWCNTs structure has superior Ca 2þ rejection efficiency to that of original nylon 66.

Understanding adsorption of divalent metals ions (Mg, Ca) on Nitrogen-, Boron- doped, and defective graphene in nanofiltration process using van der Waals density functional method

“…Extracting those bioactive substances from shrimp shell is crucial to increase the profit of processors and to mitigate the environmental population from shrimp shells waste [1][2][3][4]. In the shrimp shell processing industry, the chitin is extracted through various cycles of hydrolysis and neutralization under acidic and alkaline conditions, respectively, following by filtration [1][2][3][4][5]. After the hydrolysis and neutralization steps, the concentration of alkaline ions, e.g.…”

“…After the hydrolysis and neutralization steps, the concentration of alkaline ions, e.g. Ca 2+ , K 1+ , and Na 1+ are significantly increased due to: (1) those ions dissolution from shrimp shell and (2) the base solution in the neutralization step [1][2][3][4][5]. Those alkaline ions are then removed by filtration using ultrafiltration and nanofiltration.…”

“…Those alkaline ions are then removed by filtration using ultrafiltration and nanofiltration. High-efficiency nanofiltration based on the polymeric membranes is very promising and widely used for Ca 2+ removal from the aqueous solution for this purpose [1][2][3][4][5]. In particular, the incorporation of graphene or carbon-nanotube (CNT) into such polymeric membranes [6][7][8][9] is proved to be efficient to capture alkaline ions due to the excellent alkaline ions rejection of graphene or CNT [10][11][12][13][14][15][16].…”

“…In particular, the incorporation of graphene or carbon-nanotube (CNT) into such polymeric membranes [6][7][8][9] is proved to be efficient to capture alkaline ions due to the excellent alkaline ions rejection of graphene or CNT [10][11][12][13][14][15][16]. For instance, Nguyen et al synthesized the composite of CNT and nylon-66 and found that this composite exhibits a greater Ca 2+ rejection efficiency than original membrane [5,17]. Joshi et al studied the permeation of ions and neutral molecules through micrometer-thick graphene-oxide (GO)-based membranes and speculated that the rapid permeation of small ions arises from the enhanced interactions between the GO membrane and ions that allows a high concentration of those ions inside the membrane [14].…”

“…Unlike the numerous studies on the alkali metal ions (Na and K) capture for water desalination [18][19][20][21][22][23][24][25][26][27][28], there have been relatively few studies on the capture of divalent metal ions (Ca and Mg) by graphene [5,[29][30][31][32][33][34]. Malhotraa et al [33] investigated the adsorption of several ions (Pb, As, Cu, Zn, Cr, Hg, Ni, Cd, Ca, Li, Fe) on pristine graphene by both experiments and density functional theory (DFT) calculations.…”