Polyethylenimine Facilitated Ethyl Cellulose for Hexavalent Chromium Removal with a Wide pH Range

Abstract

Ethyl cellulose (EC) composites modified with 20.0 wt % polyethylenimine (PEI) (PEI/ECs) demonstrated effective hexavalent chromium, [Cr(VI)], removal from solutions with a wide pH range. For example, 4.0 mg/L Cr(VI) solution with a pH below 3.0 was completely purified by 3.0 g/L PEI/ECs within 5 min, much faster than the as-received EC (2 h) and activated carbon (several hours). These PEI/ECs adsorbents has overcome the low pH limitation of Cr(VI) removal; for example, 4.0 mg/L Cr(VI) solution with a pH of 11.0 was completely purified within 15 min. These adsorbents followed chemical adsorption as revealed from the pseudo-second-order kinetic study. These PEI/ECs following the isotherm Langmuir model have a maximum adsorption capacity of 36.8 mg/g, much higher than pure EC (12 mg/g), tetrabutylammonium-modified celluloses (16.67 mg/g), and magnetic carbon (16 mg/g). The reduction of Cr(VI) to Cr(III) by the oxidation of amine groups and hydroxyl groups of PEI/ECs was verified as the main mechanism for the Cr(VI) removal.

Multifunctions of Polymer Nanocomposites: Environmental Remediation, Electromagnetic Interference Shielding, And Sensing Applications

“…[55] Nanoparticles such as semiconductive materials (i. e. TiO 2 , ZnO, WO 3 ), zero-valence metal (i. e. Fe, Cu, Zn), bimetallic nanoparticles (Fe/Ni, Fe/Pd) play a key role in environmental remediation given their high interfacial reactivity with contaminants such as nitroaromatics, dyes, halogenated aliphatics, heavy metals. Poly(methyl methacrylate), [57] poly(vinylidene fluoride), [58] polysulfone, [59] polyvinyl pyrrolidone, [60] polyamine, [61] polyacrylamide [62] and polyethylenimine, [63] etc. To facilitate the separation and reuse as well as to prevent the release of these nanoparticles into the ecosystem which might impose risk to the health of human beings, a mostly used strategy is to impregnate or coat the nanoparticles onto a host.…”

Synthesis of magnetic hollow carbon nanospheres with superior microporosity for efficient adsorption of hexavalent chromium ions

“…It is clear that at lower pH values (pH 1~4), the dominant species of hexavalent chromium is HCrO 4 − , which gradually changes to CrO 4 2− as the pH increases. Importantly, HCrO 4 − is more favorably adsorbed than CrO 4 2− due …”

“…Thus, intense chromium adsorption occurred in the pH range where HCrO 4 − species were dominant. Therefore, the Cr(VI) removal efficiency and kinetics for the HCSs, HCSs-Zn-910, and Fe-HCSs-Zn-910 from acid aqueous solutions (pH 3) were investigated by conducting a series of kinetic experiments.…”

“…During the adsorption process, micropores can effectively capture guest Cr(VI) ions from the external environment due to the strong adsorption potential of the micropores. Meanwhile, at a low pH value (pH 3), fast protonation of the sample's surface active sites X-OH (X=Fe, C) form more X-OH 2 + groups and hence can adsorb HCrO 4 − through electrostatic adsorption [12,55]. As known, the redox potential (E 0 ) of the Cr(VI)/Cr(III) system depends upon solution pH, 1.3 V at pH 1 and 0.68 V at pH 5.…”

Magnetic amine-functionalized polyacrylic acid-nanomagnetite for hexavalent chromium removal from polluted water

“…[18][19][20] Zhang et al 21 reported that the thiol-functionalized multiwalled carbon nanotube/magnetite nanocomposites (CNT/Fe 3 O 4 ) showed the maximum adsorption capacity of Hg(II) and Pb(II) are 65.52 and 65.40 mg g -1 , respectively. Qiu et al 23 Fe 3 O 4 nanoparticles with an average size of 12 nm were obtained from Nanjing Emperor Nano Material Co., Ltd. All the chemicals were used as-received without any further treatment. Qiu et al 23 Fe 3 O 4 nanoparticles with an average size of 12 nm were obtained from Nanjing Emperor Nano Material Co., Ltd. All the chemicals were used as-received without any further treatment.…”