Synthesis and Application of Cationised Cellulose for Removal of Cr(VI) from Acid Mine-Drainage Contaminated Water

Abstract

Cationised hemp cellulose was prepared by etherification with two quaternary ammonium salts: 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and glycidyltrimethylammonium chloride (GTMAC) and examined for (i) the efficiency of Cr(VI) removal under acid mine-drainage (AMD) conditions, and (ii) antibacterial activity. Adsorbents were characterised by electron microscopy, Fourier transform infrared (FTIR), CP-MAS 13C nuclear magnetic resonance (NMR) spectroscopy, elemental composition and surface charge. FTIR and solid state 13C NMR confirmed the introduction of quaternary ammonium moieties on cellulose. 13C NMR also showed that cationisation decreased the degree of crystallisation and lateral dimensions of cellulose fibrils. Nevertheless, 47 % - 72% of Cr(VI) ions were removed from solutions at pH 4, by 0.1 g of CHPTAC and GTMAC-cationised cellulose, respectively. Adsorption kinetics followed the pseudo-second order model and isotherms were best described by the Freundlich and Dubinin-Radushkevich models. When GTMAC-modified cellulose was applied to AMD contaminated water (pH 2.7), however, Cr(VI) uptake removal decreased to 22% likely due to competition from Al and Fe ions. Nevertheless, cationised materials displayed considerable antibacterial effects, reducing the viability of Escherichia coli by up to 45 % after just 3 hours of exposure. Together, these results suggest that cationised cellulose can be applied in the treatment of Cr(VI)-contaminated mine water particularly if pre-treatments to reduce Fe and Al concentrations are applied.

Synthesis and application of cationised cellulose for removal of Cr(VI) from acid mine-drainage contaminated water

“…Similar findings were reported by Heux and colleagues for sugar beet cellulose ( Heux et al, 1999 ). NMR output data are available (see Underlying data , Etale et al (2020a) ).…”

“…The results show that the rate of Cr(VI) uptake by cationised cellulose was best fitted by the pseudo-second order model ( Table 3 ), suggesting that chemical sorption was the rate-limiting step of the process. Data used to assess adsorption kinetics are available (see Underlying data , Etale et al (2020a) ).…”

“…As a result of the anion-anion repulsions, approach of additional anions towards the adsorbate surface was hindered, thus limiting adsorption efficiency of the materials ( Hu et al, 2005 ; Leckie et al, 1980 ). Data used to assess adsorption isotherms are available (see Underlying data , Etale et al (2020a) ).…”

“…Furthermore, this oxidation may be of phospholipids thus compromising membrane structure, but it may also be of cellular components including proteins, lipids and DNA. Results of glutathione experiments and antibacterial cell counts are available (see Underlying data , Etale et al (2020a) ).…”

“…Figshare: Synthesis and application of cationised cellulose for removal of Cr(VI) from acid mine-drainage contaminated water. https://doi.org/10.6084/m9.figshare.13299128.v2 ( Etale et al, 2020a ).…”