Porous Carbon Materials Obtained by the Hydrothermal Carbonization of Orange Juice

Abstract

Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 °C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption isotherms. We found porous microspheres with some degree of graphitization and high nitrogen content, a specific surface of 1725 m2/g, and a pore size distribution that make them good candidates for supercapacitor electrodes.

Chinese Medicinal Herb-Derived Carbon Dots for Common Diseases: Efficacies and Potential Mechanisms

“…A number of evidences show that CDs obtained from different precursors ( Zhao et al, 2015 ; Atchudan et al, 2016 ) or preparation conditions (preparing temperature, time, et al) ( Sahu et al, 2012 ; Veltri et al, 2020 ) exhibited different properties, mainly in terms of size, charge, and chemical groups. The differences in these properties have been shown to be closely related to the bioactivities of CDs, which further offered a plausible explanation for the fact that different activities on CDs presently found ( Zhang et al, 2021 ).…”

Drying-Time Study in Graphene Oxide

“…The D** band is due to contributions from the phonon density of states in finite size graphitic crystals, C H vibrations in hydrogenated carbon, and hopping-like defects [ 51 ]. Depending on the preparation process, GO also displays a D* band related to the sp 3 diamond line on disordered amorphous carbons, but the broad region between cm −1 and cm −1 is not attributed to diamond carbon phases [ 31 , 52 , 53 ]. Although the D* band is not perceptible in non-dried GO, this band appears after the drying-time experiment (discussed below).…”

Protective Effects of Carbon Dots Derived from Armeniacae Semen Amarum Carbonisata Against Acute Lung Injury Induced by Lipopolysaccharides in Rats

“…As one of the developing nanomaterials, carbon dots (CDs) have surprising execution compared to other nanomaterials, such as ultra-fine size, predominant photoluminescence, multifunctional surface, and adjustable chemical properties. [6][7][8] Additionally, excessive evidences detailed CDs derived distinctive precursors 9,10 or preparing conditions 11,12 appeared diverse properties, primarily performed on the aspects of size, charge and chemical groups. These contrasts in properties have been illustrated to be closely associated with the bioactivities of CDs, which advance given a sound clarification for the reality that CDs right now found had diverse activities including anti-hemorrhagic, 13 anti-inflammation 14 and antioxidant.…”