scholarly journals Rice husk hydrochars from metal chloride-assisted hydrothermal carbonization as biosorbents of organics from aqueous solution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yin Li ◽  
Fana Mulugeta Hagos ◽  
Rongrong Chen ◽  
Hanxin Qian ◽  
Chengxing Mo ◽  
...  

AbstractHydrochar a carbon-rich material resulting from hydrothermal carbonization of biomass, has received substantial attention because of its potential application in various areas such as carbon sequestration, bioenergy production and environmental amelioration. A series of hydrochars were prepared by metal chloride-assisted hydrothermal carbonization of rice husk and characterized by elemental analysis, zeta potential, X-ray diffraction, Brunauer–Emmett–Teller measurements, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The results reveal that the prepared hydrochars have carbon contents ranging from 45.01 to 58.71%, BET specific areas between 13.23 and 45.97 m2/g, and rich O-containing functional groups on the surfaces. The metal chlorides added in the feedwater could improve the degree of carbonization and show significant effects on the physical, chemical and adsorption properties of the hydrochars. The adsorption of the selected organics on the hydrochars is a spontaneous and physisorption-dominated process. The hydrochars possess larger adsorption capacities for 2-naphthol than for berberine hydrochloride and Congo red, and the modeling maximum adsorption capacities of 2-naphthol are in the range of 170.1–2680 mg/g. The adsorption equilibrium could be accomplished in 10, 40 and 30 min for 2-naphthol, berberine hydrochloride and Congo red, respectively. These results suggest metal chloride-assisted hydrothermal carbonization a promising method for converting biomass waste into effective adsorbents for wastewater treatment.

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1440 ◽  
Author(s):  
Sanjeev K. Sharma ◽  
Ashish R. Sharma ◽  
Sudheer D. V. N. Pamidimarri ◽  
Jyotshana Gaur ◽  
Beer Pal Singh ◽  
...  

Biogenic silica (b-SiO2) nanopowders from rice husk ash (RHA) were prepared by chemical method and their bacterial compatibility/toxicity was analyzed. The X-ray diffractometry (XRD) patterns of the b-SiO2 nanopowders indicated an amorphous feature due to the absence of any sharp peaks. Micrographs of the b-SiO2 revealed that sticky RHA synthesized SiO2 nanopowder (S1) had clustered spherical nanoparticles (70 nm diameter), while b-SiO2 nanopowder synthesized from red RHA (S2) and b-SiO2 nanopowder synthesized from brown RHA (S3) were purely spherical (20 nm and 10 nm diameter, respectively). Compared to the S1 (11.36 m2g−1) and S2 (234.93 m2g−1) nanopowders, the S3 nanopowders showed the highest surface area (280.16 m2g−1) due to the small particle size and high porosity. The core level of the X-ray photoelectron spectroscopy (XPS) spectra showed that Si was constituted by two components, Si 2p (102.2 eV) and Si 2s (153.8 eV), while Oxygen 1s was observed at 531.8 eV, confirming the formation of SiO2. The anti-bacterial activity of the b-SiO2 nanopowders was investigated using both gram-positive (Escherichia coli) and gram-negative (Staphylococcus aureus) microorganisms. Compared to S2 and S3 silica nanopowders, S1 demonstrated enhanced antibacterial activity. This study signifies the medical, biomedical, clinical, and biological importance and application of RHA-mediated synthesized b-SiO2.


Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 655 ◽  
Author(s):  
Francesco Veltri ◽  
Francesca Alessandro ◽  
Andrea Scarcello ◽  
Amerigo Beneduci ◽  
Melvin Arias Polanco ◽  
...  

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.


NANO ◽  
2017 ◽  
Vol 12 (02) ◽  
pp. 1750017 ◽  
Author(s):  
Xinzhong Deng ◽  
Yaowu Wang ◽  
Jianping Peng ◽  
Kejia Liu ◽  
Naixiang Feng ◽  
...  

A facile cathodic electrodeposition process was developed to prepare Mg(OH)2/Graphene nanocomposites (MGN), which was used to remove Congo Red (CR), an anionic dye from aqueous solution. The morphology and phase structure were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Raman and X-ray photoelectron spectroscopy (XPS). The effects of experimental parameters, such as graphene content, adsorption time, initial concentrations of CR and pH values, on the adsorption capacity of CR were studied. The obtained MGN shows the good performance in CR, with an adsorption capacity of 1986.43[Formula: see text]mg[Formula: see text]g[Formula: see text]. The equilibrium adsorption and kinetics data fit with Langmuir isotherm and the pseudo-second-order model, respectively. Thermodynamic data suggest that CR adsorption onto MGN is spontaneous ([Formula: see text]: –9.62[Formula: see text]kJ[Formula: see text]mol[Formula: see text] at 313[Formula: see text]K, endothermic ([Formula: see text]: 36.261[Formula: see text]kJ[Formula: see text]mol[Formula: see text] and the degree of disorder increased ([Formula: see text]: 146.848[Formula: see text]J[Formula: see text]moL[Formula: see text][Formula: see text]K[Formula: see text] at the solid-solution interface. Moreover, the adsorption activation energy ([Formula: see text]: 38.929[Formula: see text]kJ[Formula: see text]mol[Formula: see text] of CR evaluated from the Arrhenius equation illustrates that it is a physical process. This adsorbent exhibits efficient adsorption properties and high recycling efficiency, making it a promising adsorbent for removing anionic dyes.


NANO ◽  
2013 ◽  
Vol 08 (05) ◽  
pp. 1350050
Author(s):  
MIN GUAN ◽  
HAI-PENG BI ◽  
ZUYUAN WANG ◽  
SHAOHUA BU ◽  
LING HUANG ◽  
...  

Mesoporous silicas SBA-15 are modified with β-Cyclodextrins (β-CD) by simple grafting method. β-CD functionalized SBA-15 was characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), nitrogen adsorption–desorption measurements, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Furthermore, the applicability of it is investigated through studying the adsorption properties of clenbuterol. It showed better adsorption capacities of clenbuterol than pure SBA-15. β-CD functionalized SBA-15 material has the potential applications in the treatment of clenbuterol contamination in food and environment science.


Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 104 ◽  
Author(s):  
Surabhi Kamal ◽  
Guan-Ting Pan ◽  
Siewhui Chong ◽  
Thomas Chung-Kuang Yang

The sulfur-doped carbon nitride/cobalt ferrite nanocomposite (SCN/CoFe2O4) was prepared via ultrasonication and studied for the sonocatalytic degradation of wastewater organic dye pollutants including methylene blue, rhodamine B, and Congo red. The X-ray photoelectron spectroscopy confirmed the presence and atomic ratios of S, C, N, Co, Fe, and O elements and their corresponding bonds with Co2+ and Fe3+ cations. The nanocomposite was found to have aggregated nanoparticles on a sheet-like structure. The bandgap energy was estimated to be 1.85 eV. For the sonocatalytic degradation of 25-ppm methylene blue at 20 kHz, 1 W and 50% amplitude, the best operating condition was determined to be 1 g/L of catalyst dosage and 4 vol % of hydrogen peroxide loading. Under this condition, the sonocatalytic removal efficiency was the highest at 96% within a reaction period of 20 min. SCN/CoFe2O4 outperformed SCN and CoFe2O4 by 2.2 and 6.8 times, respectively. The SCN/CoFe2O4 nanocomposite was also found to have good reusability with a drop of only 7% after the fifth cycle. However, the degradation efficiencies were low when tested with rhodamine B and Congo red due to difference in dye sizes, structural compositions, and electric charges.


2004 ◽  
Vol 27 (4) ◽  
pp. 353-363 ◽  
Author(s):  
Byung-Dae Park ◽  
Seung Gon Wi ◽  
Kwang Ho Lee ◽  
Adya P. Singh ◽  
Tae-Ho Yoon ◽  
...  

2020 ◽  
Vol 18 (1) ◽  
pp. 1421-1432
Author(s):  
Zhaoqin Huang ◽  
Linchao Hu ◽  
Jingyu Dai

AbstractThe properties of rice husk biochar during the ageing process in soil and the resulting impacts on sorption capacity with respect to Cu(ii) were assessed. Rice husk-derived biochar was placed in fabric bags and buried in a plastic incubator filled with soil for 0–240 d. The aged biochar was then characterised and its sorption capacity compared with control (unaged) biochar in batch sorption experiments. The structural composition and morphology of the biochar before and after ageing were analysed based on element composition, scanning electron microscopy (SEM) coupled with energy X-ray dispersive spectroscopy (EDS), diffuse reflectance infrared Fourier transform infrared spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). The concentration of O, atomic O/C ratios, and carboxyl and hydroxyl functional groups increased at the surface of the biochar during ageing, which together indicated oxidation. Within the biochar particles, O/C ratios progressively increased towards their outer surfaces. Furthermore, ageing for more than 120 d facilitated Cu(ii) sorption as oxygen-containing groups were able to develop. The maximum adsorption capacity (qm) of biochar increased by 1.24 ∼ 1.32 times after ageing in the soil for 240 d. It is suggested that biochar surface properties were gradually altered during environmental exposure and the aged rice husk biochar showed increased performance in Cu(ii) adsorption. However, the performance of aged biochar as a soil remediator or conditioner will be affected by the ageing process and interactions among different soil components. As such, further research is required to evaluate these complex effects.


Author(s):  
Tomáš Bakalár ◽  
Mária Kaňuchová ◽  
Anna Girová ◽  
Henrieta Pavolová ◽  
Rudolf Hromada ◽  
...  

In this study, the adsorption of Fe(III) from aqueous solution on zeolite and bentonite was investigated by combining batch adsorption technique, Atomic adsorption spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses. Although iron is commonly found in water and is an essential bioelement, many industrial processes require efficient removal of iron from water. Two types of zeolite and two types of bentonite were used. The results showed that the maximum adsorption capacities for removal of Fe (III) by Zeolite Micro 20, Zeolite Micro 50, blue bentonite, and brown bentonite were 10.19, 9.73, 11.64, and 16.65 mg.g−1, respectively. Based on the X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) analyses of the raw samples and the solid residues after sorption at low and high initial Fe concentrations, the Fe content is different in the surface layer and in the bulk of the material. In the case of lower initial Fe concentration (200 mg.dm−3), more than 95% of Fe is adsorbed in the surface layer. In the case of higher initial Fe concentration (4000 mg.dm−3), only about 45% and 61% of Fe is adsorbent in the surface layer of zeolite and bentonite, respectively; the rest is adsorbed in deeper layers.


2002 ◽  
Vol 17 (5) ◽  
pp. 1147-1152 ◽  
Author(s):  
Qing Yang ◽  
Kaibin Tang ◽  
Chunrui Wang ◽  
Chunjuan Zhang ◽  
Yitai Qian

Semiconductor selenides of MSe (M = Cd, Hg) nanocrystalline powders were synthesized through the reactions between metal chlorides and sodium selenosulfate in the ammoniacal aqueous solution at room temperature for 6–10 h. The samples were characterized by x-ray powder diffraction, transmission electron microscopy, electron diffraction, x-ray photoelectron spectroscopy, and elemental analysis. The average diameters of CdSe and HgSe nanocrystallites are 4 and 8 nm, respectively. The storage and an interesting phase transition under hydrothermal conditions have been presented. The absorption spectrum of the as-prepared samples exhibits obvious blue shift due to the size confinement.


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