Use Of Metal-Salt-Based Solvents For Functional Applications Of Pulp And Paper

Renewable biopolymeric(lignocellulosic)resources are the foundation of well-established pulp and paper processes.In the context of the global trend toward a "greener" future,sustainable,efficient,and fianctional use of pulp and paper is a promising strategy.With non-covalent interactions as key fundamentals associated with the use of metal-salt-based solvents,in this work,efforts were directed toward identifying new possibilities of pulp and paper for functional applications.Key hypotheses are:1.Integrated,controllable use of a solvent and a non-solvent(both are recyclable)for surface engineering of paper can result in localized liquefaction and rapid solidification,which would generate a structurally densified/miniaturized,nanostructured material with unique functionalities.Such a structural tailoring strategy would facilitate the use of paper for functional,unconventional applications.2.Both trivalent and divalent salts are known to be capable of dissolving or solubilizing carbohydate polymers(e.g.,cellulose).However,their efficiencies are somehow not satisfactory,particularly in the case of producing room-temperature-stable solutions for tailorable applications.Synergistic combination of a trivalent metal salt with a divalent metal salt may possibly formulate a solvent system with improved performance,facilitating downstream processing.For surface engineering/functionalization of paper,zinc chloride trihydrate and anhydrous ethanol were sequentially used as recyclable additives.Such a combination resulted in localized liquefaction and rapid solidification of paper under controlled conditions.The time for solvent-paper interaction was identified as a critical factor influencing structural characteristics.Pronounced impacts(e.g.,structural densification/miniaturization and nanostructurization)were achieved with a solvent-paper contact time of 10 min.The structurally reorganized paper showed interesting features,including mechanical robustness,high transparency,and oil/water-resistance.The liquid-contained surface was easily cleanable.Indeed,the concept of combining localized liquefaction with rapid solidification is easily scalable,which could be readily integrated into existing pulp and paper processes.The nanosturctured paper would find use in unconventional,high-value applications,such as those related to advanced barrier packaging materials,sensors,and electronic devices.The combined use of a trivalent salt(aluminum chloride or ferric chloride)and zinc chloride trihydate was very efficient in dissolving pulp fibers into room-temperature solutions.A pronounced synergistic impact was identified when the molar ratio of the trivalent salt to zinc chloride was 3:100.This ratio also resulted in rapid dissolution(2 min).The use of biopolymeric solutions as paper additives(via surface engineering)led to significant consolidation of fiber assemblies.Biopolymeric solutions were also converted into mechanically robust regenerated films by solution casting and hot pressing,wherein macromolecular reorganization was believed to be a key mechanism.Such biopolymeric solutions are mass-producible,which would find diversified uses in the development of sustainable bioproducts.