Natural rubber as a renewable carbon source for mesoporous carbon/silica nanocomposites

Abstract

This study is the first report on the preparation of mesoporous carbon/silica (MCS) nanocomposites with tunable mesoporosity and hydrophobicity using natural rubber (NR) as a renewable and cheap carbon source. A series of mesoporous nanocomposites based on NR and hexagonal mesoporous silica (HMS) were prepared via an in situ sol-gel process and used as precursors; then, they were converted into MCS materials by controlled carbonization. The NR/HMS precursors exhibited a high dispersion of rubber phase incorporated into the mesostructured silica framework as confirmed by small-angle X-ray scattering and high-resolution transmission electron microscopy. An increase in the carbonization temperature up to 700 °C resulted in MCS nanocomposites with a well-ordered mesostructure and uniform framework-confined wormhole-like channels. The NR/HMS nanocomposites possessed high specific surface area (500-675 m 2 g −1) and large pore volume (1.14-1.44 cm 3 g −1). The carbon content of MCS (3.0-16.1 wt%) was increased with an increase in the H 2 So 4 concentration. Raman spectroscopy and X-ray photoelectron spectroscopy revealed the high dispersion of graphene oxidelike carbonaceous moieties in MCS materials; the type and amount of oxygen-containing groups in obtained MCS materials were determined by H 2 So 4 concentration. The enhanced hydrophobicity of MCS nanocomposites was related to the carbon content and the depletion of surface silanol groups, as confirmed by the water sorption measurement. The study on the controlled release of diclofenac in simulated gastrointestinal environment suggests a potential application of MCS materials as drug carriers. Mesoporous carbon/silica nanocomposites (MCS) have received considerable attention in catalysis 1 , adsorption 2 , energy storage 3,4 , and drug delivery 5 owing to the combined advantages of inorganic silica and organic carbon in their mesostructure. Silica framework provides high mesoporosity, specific surface area, and thermal/mechanical stability. Due to the high density of silanol groups, the silica surface can be simply modified by either direct co-condensation or postsynthesis grafting to acquire various chemically active functionalities to serve a wide range of applications 6,7. However, amorphous carbon is characterized by its tunable physicochemical properties by controlling the ratio of sp 2 /sp 3 bonds and quantity of heteroatoms (i.e., oxygen) 8,9. The oxygen-containing functional groups on the carbon surface provide acidic (i.e., carboxyl, lactone, and phenol) and basic (i.e., pyrone, chromene, ether, and carbonyl) properties 10. An increase in the amount of sp 2-hybridized carbon transforms amorphous carbon into graphite-like carbon with enhanced textural properties and chemical reactivity 11,12. Typically, the preparation of MCS materials consists of two steps. The first step is to introduce an organic substance (e.g., glucose, furfuryl alcohol, phenol, and formaldehyde) as a carbon source into mesostructured silica. Then, the organic substance is converted to ...

Mesoporous Carbon Materials for Electrochemical Energy Storage and Conversion

“…The so-called hard template in this synthesis strategy plays a similar role as molds in metal casting. Silica, [46][47][48][49][50][51] polymer beads, [52][53][54][55][56] metal oxide [57][58][59][60] and zeolite [61][62][63] are the most widely used templates. A typical hard template assisting synthesis process usually involves the following steps: as presented in Figure 2a, mesoporous solid phases or colloidal crystals are first prepared as sacrificial molds.…”

Glucose Conversion into 5-Hydroxymethylfurfural over Niobium Oxides Supported on Natural Rubber-Derived Carbon/Silica Nanocomposite

“…The N2 physisorption isotherms revealed the mesoporous character of these materials (Figure 1B), according to the IUPAC classification. Compared to the pristine HMS, the mesoporosity of NR/HMS and MCS was relatively lower (Table 1) due to the presence of organic moieties dispersed in the mesostructure framework [23]. The XRD patterns of the Nb/HMS and Nb/MCS with different Nb loading amounts are shown in Figure 2A,B, respectively.…”

“…Moreover, the humins yield was insignificantly changed. Nb2O5 is an acidic oxide with excellent hydrothermal stability in the aqueous-phase reaction systems [11][12][13].The carbon moieties dispersed in the MCS nanocomposites offered hydrophobic properties [23], and so retarded the adsorption of H2O on the catalyst surface. The overall results indicated that 10-Nb/MCS not only had good catalytic activity, but also high hydrothermal stability, in the selective synthesis of HMF from an aqueous glucose solution.…”

“…Thailand is one of the world's leading producers of NR. Due to its chemical composition and hydrophobic nature, it has been used as a renewable source for preparation of polymer/silica nanocomposites with high mesoporosity for adsorption and catalysis [20][21][22][23]. Recently, we successfully prepared the MCS materials with tunable textural and hydrophobic properties using hexagonal mesoporous silica (HMS) and NR as a mesostructured framework and carbon source, respectively [23], which found potential application as a drug carrier.…”

Recent Advances in Nanotechnology with Nano-Phytochemicals: Molecular Mechanisms and Clinical Implications in Cancer Progression

“…Ceramic NPs (CNs) have emerged as drug delivery vehicles [ 46 ]. Silica nanoparticles (SNPs), discovered in 1992 by Kresge et al [ 47 ], are known to have superior textual properties, such as a high surface area, narrow pore size distribution, large pore volume, and tunable pore diameter, for disease diagnosis and cancer imaging [ 48 ]. Recently, Yuan et al [ 49 ] reported that SNPs encapsulating doxorubicin exerted antitumor effects through a burst release at an early stage and sustained release at a later stage.…”