Preparation and characterization of porous chitosan–based membrane with enhanced copper ion adsorption performance

https://doi.org/10.1016/j.reactfunctpolym.2020.104681Get rights and content

Highlights

  • Two methods were used to improve the porosity of chitosan adsorptive membranes.

  • Adsorption properties of the optimized micro-porous membrane were investigated.

  • Introducing acetone promotes pore and adsorption capacities of chitosan membranes.

  • Nonlinear regression was used to select the best isotherm and kinetics models.

Abstract

Since compactness is a disadvantageous characteristic of chitosan-based membranes, two different methods were used to increase the porosity of the chitosan/poly(vinyl alcohol)/polyethyleneimine (CS/PVA/PEI) membrane, and its effect on copper ion adsorption was studied. In the first method, selective dissolution of poly(vinyl pyrrolidone) (PVP) induced porosity and for the second method, a mixed solvent system, which consists of a volatile solvent (acetone), was used to improve the porosity of the membrane. Different percentages of PVP showed inadequate performance, but acetone improved the operation efficiency of adsorption. The membranes were characterized by the analysis of FT-IR, SEM, BET, swelling degree, and porosity. Adding acetone to the membrane mixture solution increased the adsorption capacity by about 50%. The experimental results at different temperatures (25, 35, 45 and 55 °C) showed that the Cu2+ uptake was decreased with an increase in the temperature. Furthermore, pH had an important effect on the adsorption capacity of the copper ions. Nonlinear regression was applied to fit the isothermal and kinetic models. Reusability test with 0.05 M Na2EDTA showed less than 8% reduction in adsorption capacity of the modified membrane after four cycles of adsorption–regeneration.

Introduction

Unfortunately, every industrial process inevitably produces waste that is discharged into the environment, and a growing list of metal compounds accompanied this trend [1]. The heavy metal contaminated effluent is one of the most hazardous wastewaters [2]. The high solubility of heavy metals in aqueous environments leads to their entry into the food chain of living beings; and as heavy metal ions cannot be decomposed, consumption beyond the limit of heavy metals can cause severe health disorders [3,4]. Conventional techniques for heavy metal removal from waste streams (such as ion exchange, evaporation, reverse osmosis, etc.) have some unfavorable characteristics, for example, production of toxic sludge, incomplete removal, high investment, and operating costs [5,6]. Therefore, the development of cheaper and more efficient methods to improve the quality of treated wastewater has always been considered by researchers. Low-cost adsorbents with metal-binding capability have attracted lots of consideration recently [7]. These adsorbents may be minerals, biological materials, industrial wastes, agricultural residues, biomass, and polymers [2,8].

Adsorbent membranes may have benefits over adsorbent beads in heavy metal ions removal. The adsorbent membranes have a faster separation rate than adsorbing beads [9]. Besides, lower pressure drop, easy scale-up, high adsorption capacity for compounds with very low concentrations are the other advantages of adsorptive membranes [10,11]. Moreover, functional groups such as amine and carboxyl groups at the surface of membrane adsorbents play an essential role in determining the effectiveness, capacity, selectivity, and reuse of adsorbent materials [12,13]. One straightforward and useful way to prepare effective adsorptive membranes is the use of polymer blends containing functional groups [14]. In this method, the polymer with functional groups on polymer backbones such as chitosan (CS), ethylene vinyl alcohol, cellulose acetate, or mixtures of them with other polymers such as cellulose acetate/polyethylene amine would be used as the membrane polymer [14].

Because of the unique properties of CS, CS-based materials have attracted a lot of attention in recent years. It has been demonstrated that CS is a biocompatible, biofunctional, and biodegradable polymer with no toxicogenic aspect [15,16]. Some practical applications of CS membranes include water treatment, drug delivery, biosensors, and lithium batteries [17]. This biopolymer has lots of amino groups [18], which are responsible for heavy metal ion uptake [19]. In recent studies, there is a considerable interest in the preparation of CS films instead of powder or beads [9,20]. Therefore, CS-based membrane adsorbents have been developed to remove heavy metals. However, the range of pure CS membranes application is mainly unfavorable because of its weak mechanical strength and poor chemical stability [9]. To combat these limitations, CS is usually used with other polymers; in this regard, poly(vinyl alcohol) (PVA) is one of the most effective and compatible polymers [11,19,21,22].

Since polyethyleneimine (PEI)-based materials have been studied due to their high amount of amino functional groups and the metal bonding capability [23], they have good potential for the use in adsorptive membrane blends. PEI often binds to carrier particles such as porous magnetic powder, biomass, porous cellulose materials, etc. [23]. In our previous work, introducing PEI to the CS/PVA polymer matrix membrane increased the removal of Cu (II), Ni (II), and Cd (II) by more than 40% [10]. The micro-porous adsorbent membranes have reactive groups attached to their inner pores [24]. Therefore, adsorption would not be limited to the adsorbent surface. The method used to create porosity in CS membranes is based on the selective dissolution of a component from a polymer membrane mixture [25]. For example, pore-formers such as PEG, PVP, or some salts are water-soluble and well combined with CS [19,26]. The pore-former would dissolve and leave the membrane during alkaline treatment and washing step, which leads to pores and cavity in the membrane [25]. Another simple and useful method used to create porosity in membranes is to dissolve a polymer, or a mixture of polymer in a solvent mixture consists of a volatile solvent [27]. During evaporation step, volatile solvent evaporates faster and creates more porosity [28].

The design of CS-based membranes is an interesting concept. CS-based membranes could be used for different applications in static (batch) and dynamic adsorption processes [19]. Although the structure of CS-based membranes has an important effect on the membrane adsorption performance, only a few studies are available about the porosity and its creation methods. Thus, in fabricating these membranes, we used both aforementioned methods to improve the porosity of the CS/PVA/PEI adsorbent membrane. For the first method, PVP was added to the adsorptive membrane solution mixture, and for the second method, some amount of acetone was used to increase the membrane porosity. After comparing the two methods by FT-IR, SEM, swelling degree, porosity test, and BET analysis the adsorption properties of the affinity membranes were investigated by batch adsorption experiments.

Section snippets

Materials

CS used in this study was obtained from Acros (USA). Branched polyethyleneimine with the average molecular weight of 25,000 from Aldrich was used. Poly (vinyl alcohol) and poly (vinyl pyrrolidone) were purchased from Merck (Germany). Moreover, solvents of analytical grade such as CuSO4.5H2O, NaOH, HCl, NaCl, and Na2EDTA were obtained from Merck (Germany). Acetone (extra pure, assay = 99.5%) from Arvin Shimi Delta Chemical lab (Iran) was used. Activated carbon with 4 × 8 mesh and the size of 2.4

Characterization of the polymers

Fig. 1 indicates the FTIR spectrum of CS powder. The results of the DA value for CS that was measured from the area ratio of the amide (I) and hydroxyl bands in this figure, and the molecular weight value of CS which was determination by viscosimetric methods are listed in Table 2.

GPC results for PVA and PVP including the number average molecular weight (Mn¯), weight average molecular weight (Mw¯), and Z-average molecular weight (Mz¯) are listed in Table 3.

The ratio of Mw¯/ Mn¯ shows the

Conclusion

Two methods have been used to prepare a novel porous CS membrane. Introducing PVP into adsorptive membrane casting solution did not have a very significant effect on the porosity and adsorption capacity of the membrane. The removal percent of copper ion was increased only 8.7% by the addition of 0.1% PVP. However, adding some amounts of acetone as a volatile solvent to the solution raised the membrane porosity and increased the removal amount of copper ions by about 50%. The results of

Data availability

The raw data required to reproduce these findings are included in the article.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The first author acknowledges the scholarship supported by the Azad University of Quchan in Iran. We should thank the laboratory department of this university for providing the experimental facilities and their generous help. We would also like to show our gratitude to Dr. Ehsan Salehi from Arak University for sharing his knowledge and expertise about the basics of membrane adsorbents that greatly assisted the research.

References (78)

  • V. Dodane et al.

    Pharmaceutical applications of chitosan

    Pharm. Sci. Technolo. Today.

    (1998)
  • S. Chen et al.

    Polyhexamethylene guanidine functionalized chitosan nanofiber membrane with superior adsorption and antibacterial performances

    React. Funct. Polym.

    (2019)
  • E. Salehi et al.

    Static and dynamic adsorption of copper ions on chitosan/polyvinyl alcohol thin adsorptive membranes: combined effect of polyethylene glycol and aminated multi-walled carbon nanotubes

    Chem. Eng. J.

    (2013)
  • P.O. Osifo et al.

    Transport properties of chitosan membranes for zinc (II) removal from aqueous systems

    Sep. Purif. Technol.

    (2017)
  • A. Svang-Ariyaskul et al.

    Blended chitosan and polyvinyl alcohol membranes for the pervaporation dehydration of isopropanol

    J. Membr. Sci.

    (2006)
  • O. Gil-Castell et al.

    Crosslinked chitosan/poly (vinyl alcohol)-based polyelectrolytes for proton exchange membranes

    React. Funct. Polym.

    (2019)
  • B. Han et al.

    Adsorptive membranes vs. resins for acetic acid removal from biomass hydrolysates

    Desalination

    (2006)
  • M. Zeng et al.

    Effect of compatibility on the structure of the microporous membrane prepared by selective dissolution of chitosan/synthetic polymer blend membrane

    J. Membr. Sci.

    (2004)
  • A. Ghaee et al.

    Effects of chitosan membrane morphology on copper ion adsorption

    Chem. Eng. J.

    (2010)
  • M.R. Kasaai

    A review of several reported procedures to determine the degree of N-acetylation for chitin and chitosan using infrared spectroscopy

    Carbohydr. Polym.

    (2008)
  • G. Qun et al.

    Effects of molecular weight, degree of acetylation and ionic strength on surface tension of chitosan in dilute solution

    Carbohydr. Polym.

    (2006)
  • M.R. Kasaai

    Calculation of Mark–Houwink–Sakurada (MHS) equation viscometric constants for chitosan in any solvent–temperature system using experimental reported viscometric constants data

    Carbohydr. Polym.

    (2007)
  • S. Baxter et al.

    Molecular weight and degree of acetylation of high-intensity ultrasonicated chitosan

    Food Hydrocoll.

    (2005)
  • E. Salehi et al.

    Novel chitosan/poly (vinyl) alcohol thin adsorptive membranes modified with amino functionalized multi-walled carbon nanotubes for Cu (II) removal from water: preparation, characterization, adsorption kinetics and thermodynamics

    Sep. Purif. Technol.

    (2012)
  • F. Tasselli et al.

    Mechanical, swelling and adsorptive properties of dry–wet spun chitosan hollow fibers crosslinked with glutaraldehyde

    React. Funct. Polym.

    (2013)
  • M.A. Kamal et al.

    Synthesis and adsorptive characteristics of novel chitosan/graphene oxide nanocomposite for dye uptake

    React. Funct. Polym.

    (2017)
  • Z.A. Sutirman et al.

    New crosslinked-chitosan graft poly (N-vinyl-2-pyrrolidone) for the removal of Cu (II) ions from aqueous solutions

    Int. J. Biol. Macromol.

    (2018)
  • E.C. Lima et al.

    A critical review of the estimation of the thermodynamic parameters on adsorption equilibria. Wrong use of equilibrium constant in the Van’t Hoof equation for calculation of thermodynamic parameters of adsorption

    J. Mol. Liq.

    (2019)
  • B.C. Melo et al.

    Cellulose nanowhiskers improve the methylene blue adsorption capacity of chitosan-g-poly (acrylic acid) hydrogel

    Carbohydr. Polym.

    (2018)
  • N. Bakhtiari et al.

    Adsorption of copper ion from aqueous solution by nanoporous MOF-5: a kinetic and equilibrium study

    J. Mol. Liq.

    (2015)
  • J.C.Y. Ng et al.

    Equilibrium studies for the sorption of lead from effluents using chitosan

    Chemosphere

    (2003)
  • D. Karadag

    Modeling the mechanism, equilibrium and kinetics for the adsorption of Acid Orange 8 onto surfactant-modified clinoptilolite: The application of nonlinear regression analysis

    Dyes Pigments

    (2007)
  • X. Wang et al.

    Chitosan membrane adsorber for low concentration copper ion removal

    Carbohydr. Polym.

    (2016)
  • P.C. Srinivasa et al.

    Properties and sorption studies of chitosan–polyvinyl alcohol blend films

    Carbohydr. Polym.

    (2003)
  • E.M. Abdelrazek et al.

    Chitosan filler effects on the experimental characterization, spectroscopic investigation and thermal studies of PVA/PVP blend films

    Phys. B Condens. Matter

    (2010)
  • U. Habiba et al.

    Chitosan/(polyvinyl alcohol)/zeolite electrospun composite nanofibrous membrane for adsorption of Cr6+, Fe3+ and Ni2+

    J. Hazard. Mater.

    (2017)
  • M.A. Hasan et al.

    Oxide-catalyzed conversion of acetic acid into acetone: an FTIR spectroscopic investigation

    Appl. Catal. A Gen.

    (2003)
  • Z. Cheng et al.

    Adsorption kinetic character of copper ions onto a modified chitosan transparent thin membrane from aqueous solution

    J. Hazard. Mater.

    (2010)
  • X. Wang et al.

    Poly (ethyleneimine) nanofibrous affinity membrane fabricated via one step wet-electrospinning from poly (vinyl alcohol)-doped poly (ethyleneimine) solution system and its application

    J. Membr. Sci.

    (2011)
  • Cited by (18)

    • Chitosan-based composite film adsorbents reinforced with nanocellulose for removal of Cu(II) ion from wastewater: Preparation, characterization, and adsorption mechanism

      2022, International Journal of Biological Macromolecules
      Citation Excerpt :

      Further, the addition of PVP can enhance the adsorption capacity of CS-based films for copper ion, and the film with the highest content of PVP showed the lowest resistance [3,33]. To enhance their comprehensive properties, the composite films consist of multiple materials, such as β-cyclodextrin/chitosan/polyvinyl alcohol nanofiber film, β-cyclodextrin/glutaraldehyde crosslinked PVP nanofibrous film, and chitosan/poly(vinyl alcohol)/polyethyleneimine film [33–35]. The experimental results show that the composite films have good adsorption performance to organics or heavy metal ions.

    • Prospects of titanium carbide-based MXene in heavy metal ion and radionuclide adsorption for wastewater remediation: A review

      2022, Chemosphere
      Citation Excerpt :

      The summary of the analysis of various syntheses as well as the parameters of synthesis is presented in Table 1. Heavy metal ions and radionuclides in wastewater emitted from modern industries are among the most serious emerging problems due to their non-biodegradability, polluting the environment, and posing hazardous effects on living organisms (Sahebjamee et al., 2020; Gan et al., 2020). Considering the impacts of consumption of metal ions, World Health Organization (WHO) has set guidelines on the maximum permissible limits by human beings.

    • Water stable graphene oxide metal-organic frameworks composite (ZIF-67@GO) for efficient removal of malachite green from water

      2021, Food and Chemical Toxicology
      Citation Excerpt :

      This treatment is found ineffective for removing dyes from the effluents and the biological treatment based dyes degradation needs a comparatively extended time which is not recommended for an effective way (Li et al., 2020a). The 3rd kind of method is by means of physical resources to eliminate emerging MG from water-reservoirs, comprising adsorption and precipitation (Sahebjamee et al., 2020). Considering reported literature it is observed that these dyes normally are very much stable to light, heat and are resilient to biodegradation as well as oxidation (Jibunor et al., 2020), among all above described methodologies for MG removal seems to be less effective and the adsorption seems to be an effective and smart method.

    View all citing articles on Scopus
    View full text