Microcrystalline cellulose (MCC) based materials as emerging adsorbents for the removal of dyes and heavy metals - A review

In an attempt to overcome such threats posed by water pollution, various processes ranging from physical, chemical as well as biological were applied to get rid of wastewater pollutants. The simplicity, high efficiency and cheapness of an adsorption process make it the most widely used among various other processes. Adsorbents with different properties were used in the adsorption process but this paper was focused on reviewing various articles published by numerous researchers on the isolation of microcrystalline cellulose (MCC), a popular carbohydrate polymer from lignocellulosic biomass and utilization of MCC based materials as effective adsorbents for the successful removal of dyes and heavy metals from synthetic wastewater. The sudden interest on MCC and MCC-based materials as adsorbents cannot be separated from their excellent properties such as renewability, biodegradability, biocompatibility, economic value, non-toxicity, high mechanical properties and surface area. Upon comparison with established adsorbents reported from literature, MCC-based materials performed excellently well in the adsorption of dyes and heavy metals with Langmuir isotherm and pseudo-second order reported mostly as the best fit models for the generated equilibrium and kinetic data, respectively pointing at the distribution of adsorption sites to be homogeneous as well as the formation of monolayer adsorbate on their surfaces. The various thermodynamic studies reported further revealed the adsorption processes of both dyes and heavy metals onto MCC-based materials to be entropy driven processes, spontaneous, and endothermic. Finally, future research was suggested to focus on optimization to enhance the performance of the MCC-based adsorbents, carrying out the adsorption on real wastewater instead of synthetic ones as well as expanding the range of adsorbates to include other contaminants such as chlorophenols, herbicides, pesticides and others in addition to dyes and heavy metals.