Fused sphere carbon monoliths with honeycomb-like porosity from cellulose nanofibers for oil and water separation.

Mark Adam Ferry,Jun Maruyama,Hiroshi Uyama,Taka-Aki Asoh

doi:10.1039/d0ra08950h

Abstract

Carbon monoliths with a unique hierarchical surface structure from carbonized cellulose nanofibers were synthesized in pursuit of developing carbon materials from sustainable natural resources. Through a 2-step hydrothermal – carbonization method, TEMPO-oxidized cellulose nanofibers were turned into carbon-rich hydrochar embedded with polystyrene latex as template for 80 nm-sized pores in a honeycomb pattern, while the triblock copolymer Pluronic F-127 was used for a dual purpose not reported before: (1) an interface between the cellulose nanofibers and polystyrene particles, as well as (2) act as a secondary template as ∼1 μm micelles that form hollow carbon spheres. The use of nanofibers allowed more contact between the carbon spheres to coalesce into a working monolith while optimizing the pore structure. Oil–water separation studies have shown that carbon monoliths have high adsorption capacity due to surface area and hydrophobicity. Testing against commercially available activated carbon pellets show greater performance due to highly-developed macropores.

Highlights

Porous carbon materials are known to be optimal for adsorption,[1] electrochemical,[2] and catalyst media[3] applications due to its inertness, surface morphology and high surface area
Scanning Electron Microscopy (SEM) images (Fig. 1) reveal that the minimum amount of polystyrene latex (PSL) required for signi cant pore formation starts at 32 mg (CM-S2)
It is notable that pores with diameter in multiples of the PS particle diameter is not observed, indicating that PSL is stable in the system, does not aggregate, and forms uniform pores on the surface of the material

Summary

Introduction

Porous carbon materials are known to be optimal for adsorption,[1] electrochemical,[2] and catalyst media[3] applications due to its inertness, surface morphology and high surface area. Characterization of the carbon monolith (CM) were performed to determine the optimal ratio of TEMPO-oxidized cellulose nano bers (TOCN), polystyrene latex (PSL), and Pluronic F-127 (PF 127), as well as the carbonization temperature of the hydrochar on the pore structure.

Results

Conclusion