Thermodynamics of adsorption on nanocellulose surfaces
- 27 Downloads
Understanding the thermodynamic interactions of cellulose nanomaterials with their environment is important to understand the forces behind their self-organization and co-organisation with other compounds, and to be able to use self-assembly to form new functional multicomponent materials. This review analyzes published studies that determined the thermodynamic parameters of the surface interactions of and adsorption of various compounds (proteins, polymers, and small molecules/ions) onto cellulose nanomaterials. We compiled the data reported and performed a meta-analysis for better comparison and to find trends in the published data. We first introduce the methods employed and describe the adsorption isotherm models typically used to describe the adsorption thermodynamics on nanocellulose surfaces. We then discuss and analyze the published results for the interaction of the various compounds with nanocellulose surfaces. The systems that have been reported on most were adsorption of natural binding proteins and various pollutants from water, such as heavy metal ions, dyes, and drugs. Interactions between cellulose surfaces and the cellulose binding module were generally both enthalpy- and entropy-driven, where the negative binding enthalpy indicates the formation of specific interactions between peptides and the carbohydrate backbone. On the other hand, interactions with charged molecules were mostly endothermic and purely entropy-driven, indicating that the adsorption on nanocellulose surfaces can be described as an interaction between opposite charges, where the entropy increase that arises from the release of surface-structured water molecules and counterions from the electronic double layer supplies the major contribution to the free energy of adsorption. We performed a meta-analysis on all published data, and found a linear relationship between ∆H and ∆S with the slope equal to the reference temperature, irrespective of whether the interacting compound is a specific cellulose binding protein, a non-specific binding protein, a polymer, or a small molecule/ion. This indicates that the process of adsorption is the same for all compounds and takes place with a constant change in Gibbs free energy of interaction, ∆G, where a change in interaction enthalpy is offset by change in entropy change upon binding and vice versa.
KeywordsNanocellulose Adsorption Thermodynamics Isothermal titration calorimetry
The authors would like to thank Research Foundation—Flanders (FWO) for funding under the Odysseus grant (G.0C60.13N) and research grant 1501516N, and KU Leuven for grant OT/14/072. WT also thanks the Provincie West-Vlaanderen (Belgium) for financial support through his Provincial Chair in Advanced Materials.
- Anirudhan TS, Shainy F (2015a) Effective removal of mercury(II) ions from chlor-alkali industrial wastewater using 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite. J Colloid Interface Sci 456:22–31. https://doi.org/10.1016/j.jcis.2015.05.052 CrossRefPubMedGoogle Scholar
- Anirudhan TS, Deepa JR, Christa J (2016) Nanocellulose/nanobentonite composite anchored with multi-carboxyl functional groups as an adsorbent for the effective removal of Cobalt(II) from nuclear industry wastewater samples. J Colloid Interface Sci 467:307–320. https://doi.org/10.1016/j.jcis.2016.01.023 CrossRefPubMedGoogle Scholar
- Atkins P, De Paula J (2001) Process at Solid surfaces. Atkins’ Physical chemistry, 7th edn. Oxford University Press, Oxford, pp 977–1005Google Scholar
- Chodera JD, Mobley DL (2014) NIH public access. Annu Rev Biophys 42:121–142. https://doi.org/10.1146/annurev-biophys-083012-130318 CrossRefGoogle Scholar
- De Melo JCP, da Silva Filho EC, Santana SAA, Airoldi C (2009) Maleic anhydride incorporated onto cellulose and thermodynamics of cation-exchange process at the solid/liquid interface. Colloids Surf A Physicochem Eng Asp 346:138–145. https://doi.org/10.1016/j.colsurfa.2009.06.006 CrossRefGoogle Scholar
- Giles CH, MacEwan TH, Nakhwa SN, Smith D (1960) Studies in adsorption. Part XI.* A system of classification of solution adsorption isotherms, and its use in diagnosis of adsorption mechanism and in measurement of specific surface areas of solid. J Chem Soc 846:3973. https://doi.org/10.1039/jr9600003973 CrossRefGoogle Scholar
- Hamid HA, Jenidi Y, Thielemans W et al (2016) Predicting the capability of carboxylated cellulose nanowhiskers for the remediation of copper from water using response surface methodology (RSM) and artificial neural network (ANN) models. Ind Crop Prod 93:108–120. https://doi.org/10.1016/j.indcrop.2016.05.035 CrossRefGoogle Scholar
- Mansour RA, Elmenshawy AM (2017) Removal of heavy metals from aqueous solution by adsorption onto modified cellulose: equilibrium, kinetics, and thermodynamics study. Int Water Tech J 7:116–132Google Scholar
- Mohan T, Hribernik S, Kargl R, Stana-Kleinschek K (2015) Nanocellulosic materials in tissue engineering applications. In: Matheus Poletto (ed) Cellulose—fundamental aspects and current trends, pp 251–273Google Scholar
- Myers AL (2004) Thermodynamics of adsorption. In: Letcher, Trevor M (ed) Chemical thermodynamics for industry, 1st edn. The Royal society of Chemistry, Letchworth, pp 243–254Google Scholar
- Rouquerol J, Rouquerol F (2014) Adsorption at the liquid-solid interface: thermodynamics and methodology. In: Rouquerol F, Rouquerol J, Sing KSW et al (eds) Adsorption by powders and porous solids: principles, methodology and applications, 2nd edn. Academic Press, London, pp 105–158CrossRefGoogle Scholar