The preparation, characterization and adsorption performance of the phosphate-modified hydrochar (P-hydrochar) for Pb(II) and ciprofloxacin removal are investigated. Pb(II) and ciprofloxacin ...adsorption behavior fit well with the Hill model with the adsorption capacity of 119.61 and 98.38 mg/g, respectively. Pb(II) and ciprofloxacin adsorption kinetic process are accurately described by the Pseudo-second-order. Pb(II) and ciprofloxacin have synergy in the binary contaminant system, which reveals that Pb(II) adsorption amount is augmented. While ciprofloxacin adsorption amount is also augmented at low Pb(II) concentration and hindered at high Pb(II) concentration. Pb(II) adsorption mechanisms on P-hydrochar (e.g. precipitation, π-π interaction and complexation) are different from the ciprofloxacin (e.g. hydrogen bonding, pore filling, electrostatic attraction). Pb(II) and ciprofloxacin adsorption process are further analyzed by the density functional theory. The coexisted ions have little influenced on Pb(II) and ciprofloxacin adsorption. P-hydrochar still has large Pb(II) and ciprofloxacin adsorption capacity after five cycles. This result indicates that poplar sawdust waste can be converted into an efficient adsorbent to remove Pb(II) and ciprofloxacin from wastewater,.
P Efficient removal of heavy metal and antibiotics from wastewater by phosphate-modified hydrochar. Display omitted
•P-hydrochar is successfully prepared by phosphate-modified.•P-hydrochar exhibits high Pb2+ and ciprofloxacin adsorption capacity.•Synergy between Pb2+ and ciprofloxacin adsorption contribute to their adsorption.•Pb2+ and ciprofloxacin adsorption process are investigated by DFT.
In the paper, the production of wood vinegar from Chinese fir sawdust (FS), cotton stalk (CS) and bamboo sawdust (BS) by carbonization process was addressed. The wood vinegar yield was investigated ...and the organic compounds contained were determined by gas chromatography and mass spectrometry. It was found that the refined wood vinegar yield of FS increased firstly and then decreased with increasing carbonization temperature and the highest yield reached about 25% in 350-450°C. The relative contents of acids and ketones from FS decreased and that of phenols increased with increasing temperature. The relative contents of acids and phenols in the wood vinegars produced from the samples were in the order of BS>CS>FS and that of ketones reversed. KCl solution treatment caused a decrease in the relative contents of the phenols and ketones, but an increase in that of the acids in FS wood vinegar.
Interconnected hierarchical porous carbons were synthesized via KOH-assisted hydrothermal pretreatment and carbonization of wood sawdust. KOH-assisted hydrothermal treatment can remove the lignin ...from sawdust and on the other hand, the presence of KOH facilitates the creation of macro and mesopores during the carbonization. Base-assisted hydrothermal treating time plays an important role in determining the pore structure of carbons, thus affecting their electrochemical performance. The resulting porous carbons show the highest specific capacitance of 303 F g−1 in a current density of 1 A g−1, high energy density of 17.75 W h kg−1 at a power density of 436 W kg−1, and an outstanding cycling stability. As a facile synthesis route for porous carbons from wood sawdust, such method has the potential to be directly used for industrial production, and the efficient uses of wood residue are important for sustainable development.
•KOH could degrade lignin and facilitate the formation of hierarchical pores.•The honeycomb-like porous carbon could be achieved after hydrothermal treatment.•The degradation of lignin has a positive effect to the creation of macro and mesopores.•The sawdust derived porous carbon shows the highest specific capacitance of 303 F g−1.
Today, huge amounts of coloured wastewater, released into ecosystems are a big problem, because they have harmful effects on humans, the environment, as well as the aquatic environment. One of the ...common treatments for removing dyes from wastewater is the adsorption process, with an emphasis on the use of cheap adsorbents. Therefore, the subject of this paper is the possibility of removing the anionic dye bemacid red (BR) on wood biomass sawdust and carbonized sawdust. The experiments examined the equilibrium contact time, the effect of initial pH, the effect of adsorbent dose, as well as the effect of the initial adsorbate concentration on the process of adsorption. By applying linear kinetic models, it was found that the adsorption process follows a pseudo-second-order kinetic model. It was found that pH does not have a significant effect on adsorption onto carbonized sawdust. By examining the effect of the initial adsorbent dose, it was found that optimal adsorption requires twice the mass of sawdust compared to carbonized sawdust. The use of linear adsorption isotherms shows better agreement with the Freundlich model for both adsorbents. The maximum adsorption capacity for sawdust is 30.18 mg/kg, while for carbonized sawdust it is 74.60 mg/kg. Use of sawdust and carbonized sawdust can be an effective adsorbent for removing the dye bemacid red from wastewater, which is confirmed by the experiment on a real sample of wastewater. The obtained efficiency of dye removal from real wastewater for sawdust is 42.9 %, and for carbonized sawdust 95.1 %.
•The fuel property of gasification fine slag improved by the froth flotation process.•Both synergistic and antagonistic effects exist between sawdust char and residual carbon.•Chemical components and ...carbon crystalline structure of samples were compared.•Addition of sawdust char into residual carbon significantly promoted the combustion performance.•The most effective mechanisms for multi-step co-combustion process of sawdust char and residual carbon were obtained.
This study aims to systematically investigate the physiochemical properties, co-combustion characteristic and kinetic behavior of sawdust char and residual carbon in order to guide its combustion as the potential solid fuel in the industrial-scale furnace. The froth flotation process to recycle the residual carbon from coal gasification fine slag increases the higher heating value from 7.81 to 17.70 MJ/kg and upgrade the fuel quality by effectively removing spherical mineral particles attached to the carbon particles surface or entrained in the pores. The addition of sawdust char into residual carbon could obviously improve the ignitability and combustibility of residual carbon. In the co-combustion process, both synergistic and antagonistic effects (Interaction index xd varies from −3.89 to 13.6) exist between sawdust char and residual carbon, while the synergistic effect was dominant. The first-order chemical reaction (O1) and diffusion-controlled reaction (D3 and D4) are the most effective mechanisms (all the correlation coefficient R2>0.98) for the multi-step co-combustion process. The percentage of sawdust char in blends is recommended to be maintained at 40 wt% because of the lowest combustion total activation energy (105.77 kJ·mol−1) and the strongest synergistic effect (Interaction index xd=13.6). The results provide theoretical reference for realizing the sustainable utilization of coal gasification fine slag and biomass waste resources.
Nowadays, most of the recent large-scale installations are configured to use more than one fuel. Thermal analysis allows us to properly design and operate especially such a large-scale co-pyrolysis ...and/or co-combustion process. In this study, thermal behaviours of pine sawdust (PS), coals, and their blends were investigated by using thermogravimetric analysis (TGA) under nitrogen and air atmospheres with different heating rates of 10, 20, and 40 °C min-1. Kinetic parameter such as activation energy (Ea) was calculated by using Kissenger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Starink models. The results showed the existence of an obvious synergistic effect between PS and coal during pyrolysis and combustion processes. The initial, maximum, and burnout temperatures of the reactions; the mass loss rate; and total mass loss were influenced by the proportions of PS and coal in the blend. For pyrolysis the average Ea of 25PS calculated by KAS, FWO, and Starink models was found as 31.57, 40.45, and 32.55 while that of 50PS was 166.80, 168.64, and 167.25 kJ mol-1, respectively. For combustion, the average Ea of 25PS calculated by KAS, FWO, and Starink models was found as 59.57, 67.74, and 60.52 while that of 50PS was 66.60, 74.20, and 67.49 kJ mol−1, respectively. According to the Ea value, the blend of 25PS was more suitable than 50PS for energy production through both pyrolysis and combustion. This synergistic effect between PS and coal may be further detailed with more different blend ratios.
•Co-pyrolysis & co-combustion of pine sawdust (PS) & coal was performed by TGA.•Kinetic analysis was made by using kinetic models (KAS, FWO, Starink).•Synergistic effects of co-pyrolysis & co-combustion of PS & coal were observed.•25PS was more suitable than 50PS for energy production in pyrolysis & combustion.
•Kinetic analysis of waste biomass (sawdust) was investigated through deconvolution.•Activation energy is determined by Straink (SR) and Friedman (FR) kinetic methods.•Reaction mechanism is evaluated ...by employing integral master plot method.•Thermodynamic parameters (ΔH, ΔS, and ΔG) were also determined.•Deconvolution kinetic analysis is suitable for complex decomposition processes.
Non-isothermal kinetics involved during the slow pyrolysis of waste biomass (sawdust) was investigated. The slow pyrolysis profile of sawdust was distinguished into three reactions corresponding to each pseudo component (hemicellulose, cellulose & lignin) through the deconvolution process. Kinetic triplets (activation energy, reaction mechanism & pre-exponential factor) were estimated for each pseudo component. The Straink (SR) and Friedman (FR) iso-conversional kinetic models were used to calculate the activation energy of pseudo-cellulose (SR = 162.90 kJ/mol, FR = 165.67 kJ/mol), pseudo-hemicellulose (SR = 156.25 kJ/mol, FR = 158.47 kJ/mol) and pseudo-lignin (SR = 301.62 kJ/mol, FR = 316.72 kJ/mol). The reaction mechanism involved during the slow pyrolysis of waste sawdust was identified through integral master plot method. The results revealed that the two-dimensional contract area (R2) and second order reaction (F2) reaction mechanism dominates slow pyrolysis of pseudo-cellulose and pseudo-hemicellulose, respectively. However, no exact reaction mechanism was observed for pseudo-lignin. The pre-exponential factor was determined with the help of the activation energy and reaction mechanism. Thermodynamic parameters i.e. change in enthalpy (ΔH), entropy (ΔS) and Gibb’s free energy (ΔG) were also determined for pseudo-cellulose (ΔH=157.54kJ/mol, ΔS=-17.615 J/mol and ΔG=168.64 kJ/mol) and pseudo-hemicellulose (ΔH=151.28kJ/mol, ΔS=6.61 J/mol and ΔG=147.12 kJ/mol).
Biochars made by hydrothermal carbonization and torrefaction of sawdust and peat in a wide temperature range have been studied. A comparative evaluation of the properties of the resulting materials ...was carried out by the following methods: elemental analysis, FTIR, Raman Spectroscopy, TG/TGA, SEM, Fluorescence analysis, BET. It has been established that hydrothermal carbonization has a greater effect on the degree of carbonification of the initial biomass than torrefaction. Biochars made from peat by this method have a more stable structure and contain asphaltene-like fragments and a developed system of poly-couplings. The combination of these properties makes it possible to use these materials not only as solid commercial carbon dioxide neutral fuel, but also as a promising analogue of fossil coals for the refining process.
•Peat hydrochar obtained at 230 °C obsessed asphaltene-like structures.•HTC enables directed evolution of biomass.•Thermal effect on peat is stronger than on sawdust.•HTC reduces more ash in peat then in sawdust.•Polyconjugation systems were found in hydrochars.
