Site-specific functionalization for chemical speciation of Cr(III) and Cr(VI) using polyaniline impregnated nanocellulose composite: equilibrium, kinetic, and thermodynamic modeling

Abstract

Site-specific functionalizations are the emergent attention for the enhancement of sorption latent of heavy metals. Limited chemistry has been applied for the fabrication of diafunctionalized materials having potential to tether both environmentally stable oxidation states of chromium (Cr(III) and Cr(VI). Polyaniline impregnated nanocellulose composite (PANI-NCC) has been fabricated using click chemistry and explored for the removal of Cr(III) and Cr(VI) from hydrological environment. The structure, stability, morphology, particle size, surface area, hydrophilicity, and porosity of fabricated PANI-NCC were characterized comprehensively using analytical techniques and mathematical tools. The maximum sorption performance of PANI-NCC was procured for (Cr(III): 47.06 mg g -1 ; 94.12 %) and (Cr(VI): 48.92 mg g -1 ; 97.84 %) by equilibrating 0.5 g sorbent dose with 1000 mL of 25 mg L -1 chromium conc. at pH 6.5 and 2.5 for Cr(III) and Cr(VI), respectively. The sorption data showed a best fit to the Langmuir isotherm and pseudosecond-order kinetic model. The negative value of DG°(-8.59 and -11.16 kJ mol -1 ) and DH°(66.46 9 10 -1 and 17.84 9 10 -1 kJ mol -1 ), and positive value of DS°(26.66 and 31.46 J mol -1 K -1 ) for Cr(III) and Cr(VI), respectively, reflect the spontaneous, feasibility, and exothermic nature of the sorption process. The application of fabricated PANI-NCC for removing both the forms of chromium in the presence of other heavy metals was also tested at laboratory and industrial waste water regime. These findings open up new avenues in the row of high performance, scalable, and economic nanobiomaterial for the remediation of both forms of chromium from water streams.

Cationic Dialdehyde Nanocellulose from Sugarcane Bagasse for Efficient Chromium(VI) Removal

“…As the pH value of the solution can have a strong effect on the speciation of ionic compounds and their interactions with charged surfaces, it is important to understand the pH effect on the adsorption behavior of Cr­(VI) on c-DAC samples. − As shown in Figure a, the adsorption capacities of c-DAC did not change significantly at the pH levels between 2 and 6, but they showed a slow decreasing trend when the pH level increased from 7 to 10. The decrease in the adsorption capacity of c-DAC materials at basic pH values was attributed to the change in both the speciation of chromium and adsorbent surface charge.…”

Highly Efficient Cationic/Anionic Cellulose Membranes for Removal of Cr(VI) and Pb(II) Ions

“…The chemical structure of the cellulose fabrics before and after modification was also verified by solid-state 13 C NMR, as shown in Figure 3.…”

“…The chemical structure of the cellulose fabrics before and after modification was also verified by solid-state 13 C NMR, as shown in Figure 3. It was clear that resonance peaks located at chemical shifts at 105 ppm, 89 ppm, and 65 ppm in the spectra belong to C1, C4, and C6 of cellulose structure, respectively; while the signal located in the overlap region between 71.8 and 75.4 ppm comes from C2, C3, and C5 in cellulose [23].…”

“…A high-resolution solid-state 13 C NMR (Brucker 400M, Karlsruhe, Germany) was employed to characterize the chemical structure before and after the surface modification of cellulose samples. The samples were ground into powder, dried, and loaded in the NMR tube (MAS rotation rate: 10 kHz); 13 C NMR spectra were obtained after 2000 scans at 25 • C.…”

“…On the other hand, biodegradable materials such as cellulose have original advantages in terms of high functionality, unique physicochemical properties, environmental friendliness, and cost-effectiveness. As a result, nanoscaled cellulose was employed as a highly efficient adsorbent based on various surface modifications with nanocellulose [ 11 , 12 ], polyaniline [ 13 , 14 ], and polypyrrole [ 15 , 16 ]. For example, Xu et al oxidized nanocellulose with sodium periodate and then reacted the dialdehyde nanocellulose product with activated hydrogen on black vitrine tannin.…”