Optimizing the Preparation of Meso- and Microporous Canola Stalk-Derived Hydrothermal Carbon via Response Surface Methodology for Methylene Blue Removal

Abstract

In this work, design of experiments–response surface methodology (RSM) was implemented to predict the importance of hydrothermal carbonization (HTC) key parameters and their interactions in the preparation of canola-stalk-derived hydrochar via HTC technique. According to the RSM results, temperature and reaction time were found to be the most important control factors. The possible optimum conditions were found to be 207 °C and 82 min for temperature and time, respectively, in order to achieve a hydrochar with the maximum mass yield (solid yield 53.38%), carbon recovery rate (52.66), and O/C ratio (0.69). Furthermore, the optimized hydrochar was successfully activated via potassium hydroxide (KOH), under mild activation conditions. Synthesized microporous activated carbon demonstrated the highly improved Brunauer–Emmett–Teller (BET) surface area of 474.87 m2 g–1 compared to the low BET surface area of mesoporous hydrochar (S BET of 2.69 m2 g–1). Porous activated carbon was used as an adsorbent for methylene blue removal that showed a promising dye removal capacity of 93.4 mg g–1. The morphological and chemical compositions of the solid materials were analyzed by various techniques, including elemental analysis, field emission scanning electron microscopy (FESEM), BET analysis, Fourier transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray spectroscopy.

Synergistic Effect of Nitrogen Doping and Ultra-Microporosity on the Performance of Biomass and Microalgae-Derived Activated Carbons for CO2 Capture

“…The experimental procedure for HTC has been described in detail before. 31 Briefly, each HTC process is comprised of mixing CAWL (carbon source), S. platensismicroalgae (nitrogen source), and deionized water in a 100 mL stainless steel Teflon-lined hydrothermal synthesis autoclave reactor (Figure 1, Supporting Information Video). Three grams of CAWL powder was mixed with the appropriate amount of microalgae based on the required microalgae/biomass weight ratio.…”

Investigation of Hydrochar Derived from Male Oil Palm Flower: Characteristics and Application for Dye Removal

“…The extent of the surface area revealed that the HTC process leads to a low porosity-based material. However the value obtained was slightly higher than that for hydrochar prepared from canola stalk by HTC at 207ºC for 82 min (2.69 m 2 •g -1 ) [26]. Tran et al [20] prepared hydrochar from golden shower at 190ºC for 24 h, which produced a surface area (24.80 m 2 •g -1 ) almost three times higher than the precursor (8.14 m 2 •g -1 ), which was due to the weak decomposition of cellulose and lignin during the HTC process.…”

“…The broad band at 3200-3600 cm -1 corresponds to the stretching vibration of O-H groups from the phenol groups of hemicellulose, cellulose, and lignin and N-H stretching vibration [31]. However, the hydroxyl peak in the MOPF was stronger than in the hydrochar due to the organic acid content in the biomass consisting of carboxyls, phenols and/or chemisorbed water [19,30] and due to the removal of the H and O from the hydrochar due to the dehydration and decarboxylation processesduring the formation of H 2 O and CO 2 as liquid products [26]. C-H stretching in the aliphatic CH, CH 2 , and CH 3 groups and aromatic C=C bending (due to the aromatic characteristic of lignin) are apparent at the bands at 2920 cm -1 and 1620 cm -1 , respectively.…”

“…Conversely, the peak at 1249 cm -1 assigned to C-O (alcohols, carboxylic acids, esters, and ethers), did not appear in the hydrochar spectrum because of the decarboxylation reaction during the HTC process. The taper band at 780 cm -1 in the hydrochar indicates deformities due to out-of-plane angular benzene derivatives that were assigned to =CH bending vibration [26].…”

Performance optimization of polymeric porous membrane-based liquid desiccant air dehumidifier used in air conditioning system

“…Nowadays, the membrane-based liquid desiccant air dehumidification which had been mostly applied in wastewater treatment processes has become more interesting for researchers worldwide, who are investigating the field of air conditioning systems [12]. This technology, which is a thermally driven separation process, utilizes the vapor pressure difference across the porous membrane as a driving force to achieve successful separation and dehumidification [13]. The most important difference between this method and the conventional liquid desiccant air dehumidification is the utilization of semi-permeable membranes for the separation of the processing air and liquid desiccant fluids which generally results in the successful inhibition of liquid from penetrating [14].…”