Functionalized Cellulose for Water Purification, Antimicrobial Applications, and Sensors

Hydrogels are being investigated recently for wastewater treatment. These polymeric networks permit their functional group alterations imparting high binding affinity for different contaminants in wastewater. Their innate ability to imbibe huge volume of water qualifies it for a smart material for water remediation. In this review recent advancements in the modifications and types of hydrogels with particular emphasis on adsorption capacity of metal ions and dyes is presented. In addition, through a comparative approach, adsorption mechanism, kinetic, isotherm and related thermodynamics parameters of the modified hydrogels have been discussed. It gives a detailed account of the work done by different authors on the synthesis, composition, functionality and contaminant removal mechanism. It also provides an in-depth perspective on the advantages and limitations in the application of hydrogels for wastewater treatment.

Advances in the preparation of hydrogel for wastewater treatment: A concise review

Novel modified Ni/Fe layered double hydroxides with different morphology of spherical - like shape were fabricated via using urea as a ligand and glycerol (Ni/Fe LDH/GL) with Ni:Fe molar ratios of 2:1 by the simplest co -precipitation method. Also, for comparison purposes, Ni/Fe LDH was synthesized to be used as a control one. A suggested interpretation for the morphology change was also given. The materials were characterized by X-ray diffraction (XRD), The Fourier transform infrared (FT - IR) spectroscopy, field emission scanning electron microscopy (FESEM), EDX for elemental analysis, high resolution transmission electron microscopy (HRTEM), Brunauer, Emmett, and Teller (BET) equation, particle size distributions and Zeta potential measurements. In addition, the synthesized materials were used as adsorbents for removal of potassium dichromate from aqueous solutions under various experimental conditions. The adsorption of Cr (VI) was strongly pH dependant and the pHPZC was studied. Kinetic studies were evaluated through different models including, pseudo first and second orders, mixed 1, 2 orders, intra particle diffusion and Avrami models. For adsorption isotherms, two-parameter models (Langmuir, Freundlich and Temkin) and three parameter models (Sips, Langmuir-Freundlich and Tooth) were investigated showing maximum adsorption capacity of 50.43 mg/g and 136.05 mg/g for Ni/Fe LDH and Ni/Fe LDH/GL, respectively. Also, the effect of temperature was investigated at (23, 35, 45, 55 °C) and the thermodynamic parameters (∆H°, ∆S° and ∆G°) were calculated showing exothermic and spontaneous adsorption process. The effect of coexisting anions (Cl-, SO42- and HPO42-) and humic acid at different concentrations on the removal efficiency of dichromate ions was investigated. Chemical stability and recyclability of these adsorbents were also studied. The intermolecular hydrogen bonds formation between dichromate ion, urea, glycerol, LDH was explored by Monte Carlo simulation This study suggested that the modified Ni/Fe LDH/GL materials were promising nanoadsorbents for efficient potassium dichromate removal.

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Novel synthesis of Ni/Fe layered double hydroxides using urea and glycerol and their enhanced adsorption behavior for Cr(VI) removal

Adsorption of Pb(II) from aqueous solutions using crosslinked carboxylated chitosan/carboxylated nanocellulose hydrogel beads

Considerable interest has been devoted to developing nanoscale biomass materials as adsorbents for wastewater treatment. A facile route was proposed to prepare cellulose-based composite nanofibers via electrospinning of cellulose acetate with organically modified montmorillonite, followed by deacetylation. The composite nanofibers are suitable for metal adsorption given their reasonably high selectivity in removing Cr 6+ ions from aqueous solution. The effects of experimental parameters, including solution pH, temperature, and contact time, on the removal of Cr 6+ ions were determined in a batch system to optimize the adsorption conditions. Results from this study may provide a promising biosorbent that can be used as an emerging material in large-scale adsorption of heavy metal ions.

Electrospun composite nanofiber mats of Cellulose@Organically modified montmorillonite for heavy metal ion removal: Design, characterization, evaluation of absorption performance

The major problem in heavy metal pollution is that these metals are not biodegradable and accordingly accumulate in the bodies of living organisms, causing dangerous diseases and serious cell disorder. According to World Health Organization (WHO), the long term exposure of Cr(VI) levels of over 0.1 ppm causes respiratory problems, liver and kidney damage, and carcinogenicity.Due to its easy operation and of various cheap adsorbents development, adsorption has been proved to be efficient and most economically attractive technique and feasible to the removal of toxic heavy metal from wastewater. The study aimed to report the removal of Cr(VI) ions from aqueous solutions through adsorption process using carboxymethyl cellulose-graft-poly(acrylic acid) (CMC-g-PAA) hydrogel as adsorbent.Effect of pH was studied to remove hexavalent chromium.Graft copolymerization of poly(acrylic acid) onto carboxymethyl cellulose was carried out in the presence of benzoyl peroxide redox initiator and methylenbisacrylamide as crosslinker agent. Batch experiments were carried out to investigate the effects ofinitial pH.The adsorption of Cr(VI) ions as a function of pH was conducted in the initial pH range of 1 to 8. The results indicated that acidic pH strongly favored the adsorption. The optimum pH for adsorption of Cr(VI) ranged from 1 to 3, and the maximum uptake of Cr(VI) from the solution was 6.53 mg/g at pH 1 and 30°C. FTIR spectroscopy, SEM analyses were performed on the adsorbent before and after Cr(VI) binding. All analyses confirmed the complexation of Cr(VI) ions on the adsorbent.

https://iopscience.iop.org/article/10.1088/1755-1315/60/1/012010/pdf

Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

Summary


Batch experiments of adsorption of heavy metals cations from aqueous solution by using carboxymethyl cellulose-graft-poly(acrylic acid)/monmorilonite (CMC-g-PAA/MT) hydrogel composite were carried out. The parameter such as different pH and the presence of other ions as competitor were studied to observe their effects on the adsorption capacity of the hydrogel composite. The results showed that the adsorption of metal ions by the hydrogels was higly pH dependent, and maximum adsorption was obtained at pH 5.0. At this pH, the adsorption capacities of hydrogels for the Pb2+ and Zn2+ ions were 146.19 mg/g and 286.67 mg/g, respectively. The hydrogels can be regenerated after releasing metal ions by washing with low pH solution and reused two times. Based on the scanning electron microscope (SEM) images and Fourier transform infrared spectroscopy (FTIR) spectra before and after adsorption by the hydrogels revealed that the complex formation between heavy metal ions and carboxyl groups of the hydrogels was the main adsorption mechanism.

Adsorption of Heavy Metal Ion from Aqueous Solution by Using Cellulose Based Hydrogel Composite

This paper reports the removal of nickel ions from aqueous solutions using carboxymethyl cellulose-graft-poly(acrylic acid) CMC-g-PAA hydrogel as an adsorbent. The hydrogel was prepared through graft copolymerization of acrylic acid monomer onto a carboxymethyl cellulose backbone in the presence of N,N'-methylenebisacrylamide as a crosslinking-agent using benzoyl peroxide initiator system. Isotherm for the adsorption of nickel on CMC-g-PAA hydrogel was developed and the equilibrium data fitted to the Langmuir and Freundlich isotherm models. The result showed that at pH of 5 and shaker speed of 100 rpm, Freundlich model was better fitted than Langmuir model, of which R2 = 0.999 and R2 = 0.935, respectively. The constant of Langmuir model was KL value = 0.003 and qmax = 1000 mg/g, whereas the constant of Freundlich model n = 1.2 and KF = 4.614. The CMC-g-PAA hydrogel before and after Ni(II) adsorption were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR).

https://iopscience.iop.org/article/10.1088/1755-1315/160/1/012017/pdf

Isotherm adsorption studies of Ni(II) ion removal from aqueous solutions by modified carboxymethyl cellulose hydrogel

Crosslinking Parameter on the Preparation of Cellulose Based Hydrogel with Divynilsulfone

Summary


The grafted copolymer CMC-g-PAA has been prepared by graft copolymerization reaction using 10% w/w carboxymethyl cellulose (CMC), acrylic acid (AA), 2.5% w/w benzoyl peroxide (BPO) as initiator, 3.75% w/w methylenbisacrylamide (MBA) as crosslinking agent in distilled water at 30, 50, 70, and 90 °C during reaction periods of 30 to 300 min and composited with 10% w/w montmorillonite for 5 h.The grafted copolymer CMC-g-PAA and homopolymer were dried in the oven at 40 °C, then washed with distilled water and aceton. After that the hydrogel material was dried, and subjected to Soxhlet extraction with dioxane to separate the homopolymer, poly(acrylic acid), from the graft copolymer, CMC-g-PAA. The water absorption capacities and grafting values of grafted CMC were also determined. The graft copolymer CMC-g-PAA obtained at 30 °C has high conversion rate of AA (87.6%). The maximum grafting yield (99.181%) and the lowest of homopolymer formation (0.819%) were obtained at 50 °C. It was observed that polyacrylic acid-grafted CMC produced at 90 °C had the highest water retention capacity (55.03%). The graft copolymer was characterized by infra-red spectroscopy to determine the structure of the graft chains.

Lik Anah

Papers

Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

Adsorption of Heavy Metal Ion from Aqueous Solution by Using Cellulose Based Hydrogel Composite

Isotherm adsorption studies of Ni(II) ion removal from aqueous solutions by modified carboxymethyl cellulose hydrogel

Crosslinking Parameter on the Preparation of Cellulose Based Hydrogel with Divynilsulfone

The Effect of Temperature on the Grafting of Acrylic Acid onto Carboxymethyl Cellulose