Functionalized Cellulose for Water Purification, Antimicrobial Applications, and Sensors

Abstract

As the most abundant natural polymer, cellulose presents a unique advantage for large-scale applications. To fully unlock its potential, the introduction of desired functional groups onto the cellulose backbone is required, which can be realized by either chemical bonding or physical surface interactions. This review gives an overview of the chemistry behind the state-of-the-art functionalization methods (e.g., oxidation, esterification, grafting) for cellulose in its various forms, from nanocrystals to bacterial cellulose. The existing and foreseeable applications of the obtained products are presented in detail, spanning from water purification and antibacterial action, to sensing, energy harvesting, and catalysis. A special emphasis is put on the interactions of functionalized cellulose with heavy metals, focusing on copper as a prime example. For the latter, its toxicity can either have a harmful influence on aquatic life, or it can be conveniently employed for microbial disinfection. The reader is further introduced to recent sensing technologies based on functionalized cellulose, which are becoming crucial for the near future especially with the emergence of the internet of things. By revealing the potential of water filters and conductive clothing for mass implementation, the near future of cellulose-based technologies is also discussed.not suitable for drinking water treatment in rural areas or not applicable on a large scale. Other methods involving materials which have high adsorption capacities for pollutants, for example activated charcoal have been explored. [27,28] Nevertheless, there are no universal adsorbents for all pollutants, meaning that superior alternatives are still required. In recent years, biodegradable adsorbents such as cellulose and chitosan have attracted much attention for the removal of heavy metals.In particular cellulose has a number of advantages, which include high abundance, low cost, easy access, nontoxicity and biodegradability. It is particularly suited for the removal of low concentrations of heavy metals which occur in contaminated ground or tap water. [26] Beyond the aspects of copper removal from water, in this review we indicate how the metal's increased toxicity for microbial life can present an advantage for medical applications. Moreover, we also take a closer look at further applications of functionalized cellulose, including catalysis and sensing, which can make a great impact regarding energy conversion and management. The inclusion of conductive cellulose sensors within the internet of things global network is of particular interest, since an accurate weather forecast can provide swift adjustments in the usage of the often intermittent renewable energy sources. In order to understand what confers functionalized cellulose its versatility for broad applications, we first exemplify the functionalization techniques on a molecular basis.

Wide range humidity sensors printed on biocomposite films of cellulose nanofibril and poly(ethylene glycol)

“…Usually, they are well usable for capacitive and resistive humidity sensing with simple electronic evaluation. 43 As stated in the review, 44 several studies confirmed that the electrical properties of cellulose are sensitive to the concentration of water vapor. 40,41 Organic materials are particularly interesting in terms of their environmental compatibility as was demonstrated on a sensor based on biopolymer Keratin, which is naturally nontoxic, biocompatible, and biodegradable.…”

Functionalized Cellulose‐Co(II)‐Bis‐Terpyridine Hybrid Material as Colorimetric Sensor for Micromolar Aqueous Cyanide

“…Cellulose is the most abundant natural polymer; it is nontoxic and inexpensive. A rational functionalization of cellulose has been shown to have applications in various areas like water purification, antibacterial action, sensing, energy harvesting, and catalysis . However, there are only a handful examples of functionalized cellulose as sensors, where chemically functionalized cellulose is used for colorimetric sensing of metal ions like Ni II , Cu II , and Fe III .…”

Biofabrication of a novel bacteria/bacterial cellulose composite for improved adsorption capacity

“…To preliminarily assess the effect of the presence of BA in BC on the adsorption of metal ions, adsorption assays of BA/BC and BC without surface functionalization were performed which may increase the adsorption capacity of cellulose [19,27]. Pb(II) was chosen as a model metal ion and the adsorption of BA/BC and BC under various conditions was assessed.…”