Search

This research deals with the effect of the temperature on the physical, thermal, electrochemical, and adsorption properties of the carbon micro-spheres using hydrothermal carbonization (HTC). Until recently, limited research has been conducted regarding the effects of delignification during the HTC process of biomass residues especially Dimocarpus longan. In this regard, lignin was first extracted fromthe lingo-cellulosic waste of Longan fruit peel (Dimocarpus longan). The holocellulose (HC) separated from lignin and raw biomass substrates (Longan fruit exocarp/peel powder, LFP) were carbonized at different temperatures using water as the green catalyst. Hydrothermal carbonization (HTC) was performed for both of the samples (LFP and HC) at 200 °C, 250 °C, and 300 °C for 24 h each. The surface morphological structures, the porosity, and the Brunauer-Emmett-Teller (BET) surface area of the prepared micro-spherical carbon were determined. The BET surface areas obtained for HC-based carbon samples were lower than that of the raw LFP based carbon samples. The carbon obtained was characterized using ultimate and proximate analyses. The surface morphological features and phase transformation of the synthesized micro-spherical carbon was characterized by a field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis. The results demonstrated that the extraction of lignin could significantly alter the end properties of the synthesized carbon sample. The carbon spheres derived from LFP showed a higher carbon content than the HC-based carbon. The absence of lignin in the holo-cellulose (HC) made it easy to disintegrate in comparison to the raw, LFP-based carbon samples during the HTC process. The carbonaceous samples (LFP-300 and HC-300) prepared at 300 °C were selected and their adsorption performance for Pb (II) cations was observed using Langmuir, Freundlich, and Temkin linear isotherm models. At 30 °C, the equilibrium data followed the Langmuir isotherm model more than the Freundlich and Temkin model for both the LFP-300 sample and the HC-300 sample. The potential of the synthesized carbon microspheres were further analyzed by thermodynamic characterizations of the adsorption equilibrium system. [ABSTRACT FROM AUTHOR]

The effect of temperature on the physiochemical characteristics of a solid fuel or biocoal derived from the dried trunk of Adansonia digitata (Baobab) was studied using torrefaction processes. The chemical composition of the solid fuel or char obtained by wet (HTC) and dry torrefaction processes were determined by elemental and thermogravimetric (TGA) analyses. The Brunauer-Emmett-Teller (BET) surface area analyzer measured the porous texture and surface area of the prepared samples. The changes in the surface morphology and crystallinity of the prepared samples were evaluated by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The torrefaction process successfully improved the energy content from 16.8 MJ/kg to 22.0 MJ/kg, which was evidently higher than the starting precursors. The maximum energy yield obtained was 90.0% using dry torrefaction at 250 °C. The energy densification ratio was also higher for the char produced by the dry torrefaction process. However, the char produced by the HTC process at 250 °C showed the highest surface area. The pore diameter was higher for HTC-char produced at the same temperature. Overall the results revealed that the torrefaction of lignocellulosic biomass is beneficial for upgrading the fuel quality and energy densification of char residues. [ABSTRACT FROM AUTHOR]

Micellar-enhanced ultrafiltration (MEUF) was applied to remove cadmium ion from wastewater using sodium dodecyl sulfate (SDS) as a micelle in this study. Investigations were carried out on operational parameters such as initial permeate flux, retentate pressure, initial cadmium concentration, pH solution, molecular weight cut-off (MWCO), and molar ratio of cadmium to SDS. Removal efficiency of cadmium increased with increase in retentate pressure, pH solution, and molar ratio of cadmium to SDS and decreased with increase in initial permeate flux. Higher removal efficiency of cadmium was achieved using lower MWCO. In optimized experimental condition, cadmium removal efficiency reached 75% within an hour. With MEUF–ACF hybrid process, removal efficiencies of cadmium and SDS were found to be over 99 and 90%, respectively. Freundlich isotherm equation fitted better with experimental results on adsorption of SDS by ACF than Langmuir isotherm equation. Overall SDS removal efficiency of ACF unit in series was 90%. [ABSTRACT FROM AUTHOR]

This study attempted to remove an organic from an aqueous solution (wastewater) using submerged plasma irradiation (SPI) process. N, N-Dimethyl-4-nitrosoaniline (RNO) was used as a target material. Effect of electrode materials, applied voltage, initial concentration, and two types of buffer solutions were studied with the purpose of monitoring the pollutant removal. The degradation of RNO by SPI process followed a first-order kinetics model. While applying SPI, in comparison with the alkaline condition (carbonate buffer), the neutral condition (phosphate buffer) proved to be much more applicable in dealing with RNO contained by wastewater. After 8 min of operation, the removal efficiencies were found to be over 70% in the case of the carbonate buffer solution, and respectively 90% in the case of the phosphate one. By increasing the operation time and applied voltage, the SPI process had a significant effect on the pollutant removal. In comparison with the tungsten and aluminum electrodes, the iron one showed a higher efficiency in the removal process. Instead of using a high concentration pollutant in the initial stage, it was more beneficial to dilute the RNO wastewater before applying the SPI method. [ABSTRACT FROM AUTHOR]