scholarly journals Enhanced removal of hexavalent chromium by different acid-modified biochar derived from corn straw: behavior and mechanism

2020 ◽  
Vol 81 (10) ◽  
pp. 2270-2280
Author(s):  
Yonggang Xu ◽  
Tianxia Bai ◽  
Yubo Yan ◽  
Yunfeng Zhao ◽  
Ling Yuan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Ion ◽  
Corn Straw ◽  
Order Model ◽  
Freundlich Model ◽  
X Ray ◽  
Modified Biochar ◽  
Before And After ◽  
Pseudo Second Order ◽  
Kinetics Of

Abstract It is of great significance to remove Cr(VI) from water as a result of its high toxicity. Biochar from corn straw was modified by different acids (HNO3, H2SO4 and H3PO4) to remove Cr(VI) from aqueous solution. To estimate the removal mechanisms of Cr(VI) by the acid-modified biochars, batch experiments were performed in the light of contact time, Cr(VI) concentration, and pH, and the characteristics of acid-modified biochars before and after Cr(VI) adsorption were investigated by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of Cr(VI) by acid-modified biochars were consistent with the pseudo-second-order model, and the adsorption isotherm obeyed the Freundlich model. Furthermore, the acid- modified biochars could supply more oxygen-containing functional groups (-COOH and -OH) as electron donor (e−) and hydrogen ion (H+) to enhance the reduction of Cr(VI) to Cr(III), resulting in enhanced removal of Cr(VI). HNO3-modified biochar exhibited the highest removal efficiency of Cr(VI). In general, the acid modifition of biochar was an effective method to increase the removal of Cr(VI).

scholarly journals Synthesis of Nanoscale Zerovalent Iron (nZVI) Supported on Biochar for Chromium Remediation from Aqueous Solution and Soil

2019 ◽  
Vol 16 (22) ◽  
pp. 4430 ◽  
Author(s):  
Haixia Wang ◽  
Mingliang Zhang ◽  
Hongyi Li
Keyword(s):  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Zero Valent Iron ◽  
Zerovalent Iron ◽  
X Ray ◽  
Nanoscale Zerovalent Iron ◽  
Before And After ◽  
Pseudo Second Order ◽  
Xrd Patterns ◽  
Co Precipitation

Maize straw biochar-supported nanoscale zero-valent iron composite (MSB-nZVI) was prepared for efficient chromium (Cr) removal through alleviating the aggregation of zero-valent iron particles. The removal mechanism of MSB-nZVI was investigated by scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). Cr(VI) removal from aqueous solution by MSB-nZVI was greatly affected by pH and initial concentration. The removal efficiency of Cr(VI) decreased with increasing pH, and the removal kinetics followed the pseudo-second-order model. XRD patterns of MSB-nZVI before and after reaction showed that reduction and precipitation/co-precipitation (FeCr2O4, Fe3O4, Fe2O3) occurred with the conversion of Cr(VI) to Cr(III) and Fe(0) to Fe(II)/Fe(III). The produced precipitation/co-precipitation could be deposited on the MSB surface rather than being only coated on the surface of nZVI particles, which can alleviate passivation of nZVI. For remediation of Cr(VI)-contaminated saline–alkali soil (pH 8.6–9.0, Cr 341 mg/kg), the released amount of Cr(VI) was 70.7 mg/kg, while it sharply decreased to 0.6–1.7 mg/kg at pH 4.0–8.0, indicating that the saline–alkali environment inhibited the remediation efficiency. These results show that MSB-nZVI can be used as an effective material for Cr(VI) removal from aqueous solution and contaminated soil.

scholarly journals Adsorption of As(V) by the Novel and Efficient Adsorbent Cerium-Manganese Modified Biochar

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2720
Author(s):  
Ting Liang ◽  
Lianfang Li ◽  
Changxiong Zhu ◽  
Xue Liu ◽  
Hongna Li ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Photoelectron Spectroscopy ◽  
Water Environment ◽  
Polluted Water ◽  
X Ray ◽  
Modified Biochar ◽  
Wide Ph Range ◽  
Infrared Spectrometer ◽  
Pseudo Second Order ◽  
Ph Range

Arsenic has become a global concern in water environment, and it is essential to develop efficient remediation methods. In this study, a novel adsorbent by loading cerium and manganese oxide onto wheat straw-modified biochar (MBC) was manufactured successfully aiming to remove arsenic from polluted water. Through scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), and other techniques, it was found the loading of cerium and manganese oxide on MBC played a significant role in As(V) adsorption. The results of the batch test showed that the adsorption of MBC followed the pseudo-second order kinetics and Langmuir equation. The adsorption capacity of MBC was 108.88 mg As(V)/g at pH = 5.0 (C0 = 100 mg/L, dosage = 0.5 g/L, T = 298 K) with considerable improvement compared to the original biochar. Moreover, MBC exhibited excellent performance over a wide pH range (2.0~11.0). Thermodynamics of the sorption reaction showed that the entropy (ΔS), changes of enthalpy (ΔH) and Gibbs free energy (ΔG), respectively, were 85.88 J/(moL·K), 22.54 kJ/mol and −1.33 to −5.20 kJ/mol at T = 278~323 K. During the adsorption, the formation of multiple complexes under the influence of its abundant surface M-OH (M represents the Ce/Mn) groups involving multiple mechanisms that included electrostatic interaction forces, surface adsorption, redox reaction, and surface complexation. This study indicated that MBC is a promising adsorbent to remove As(V) from polluted water and has great potential in remediating of arsenic contaminated environment.

scholarly journals Adsorption of Thymol onto Natural Clays of Morocco: Kinetic and Isotherm Studies

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Hamid Ziyat ◽  
Mohammed Naciri Bennani ◽  
Hassan Hajjaj ◽  
Omar Qabaqous ◽  
Said Arhzaf ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
X Ray Diffraction ◽  
Order Model ◽  
Freundlich Model ◽  
Kinetics Of Adsorption ◽  
Adsorption Capacities ◽  
Pseudo Second Order ◽  
Natural Clays ◽  
Uv Visible ◽  
Kinetics Of

The present work aims to study the affinity of a component of the thyme essential oil “thymol” to natural Moroccan clay “Rhassoul” using the adsorption technique. The physicochemical characterizations of the purified and modified clay were carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), DTA/TGA, and SEM-EDX. Thymol adsorption tests on the purified Rhassoul (Rh-P) and the modified one by CTAB (Rh-CTAB) were followed by UV-visible spectroscopy. They show that the adsorption isotherms can be described by the Freundlich model and that the kinetics of adsorption is in accordance with the pseudo-second-order model for the two clays. Adsorption capacities obtained were of the order of 6 mg/g for the purified Rhassoul and 16 mg/g for the modified Rhassoul by cetyltrimethylammonium bromide (CTAB). These values show that the modified Rhassoul has a better adsorption capacity compared to the purified Rhassoul.

scholarly journals Adsorbing low concentrations of Cr(VI) onto CeO2@ZSM-5 and the adsorption kinetics, isotherms and thermodynamics

2018 ◽  
Vol 77 (9) ◽  
pp. 2327-2340 ◽  
Author(s):  
Jianrui Niu ◽  
Xiuxiu Jia ◽  
Yaqing Zhao ◽  
Yanfang Liu ◽  
Weizhang Zhong ◽  
...  
Keyword(s):  
Adsorption Kinetics ◽  
Photoelectron Spectroscopy ◽  
Bet Surface Area ◽  
Isotherm Models ◽  
X Ray ◽  
Low Concentrations ◽  
Freundlich Adsorption Isotherm ◽  
Pseudo Second Order ◽  
Isotherms And Thermodynamics ◽  
Kinetics Of

Abstract The CeO2@ZSM-5 was prepared by the dipping method. We used ZSM-5 and CeO2 as the carrier and load components, respectively. The aim was to reduce the low concentration of Cr(VI) in simulated wastewater (the concentration of Cr(VI) ranged from 0.2 to 1 mg/L). The characteristics of ZSM-5 and CeO2@ZSM-5 samples were determined by X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET). Characterization results showed that the particle size, BET surface area and pore volume for CeO2@ZSM-5 was around 0.783 nm, 421.307 m2/g and 0.313 m3/g, respectively. In addition, the optimum conditions were obtained by the orthogonal test, and the details were as follows: optimal pH, adsorbent dose, initial concentration of Cr(VI) and equilibrium time were 3, 5 g/L, 0.6 mg/L and 70 min respectively. The removal of Cr(VI) was 99.56% in these conditions. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto CeO2@ZSM-5. Isotherm data were treated according to Langmuir, Freundlich and Temkin isotherm models. The results showed that the Freundlich adsorption isotherm model fitted best in the temperature range studied. Adsorption capacity increased with temperature, showing the endothermic nature of Cr(VI) adsorption. The desorption results showed the best recovery of Cr(VI) using 0.1 M HCl.

scholarly journals Application of a Low-Cost Cellulose-Based Bioadsorbent for the Effective Recovery of Terbium Ions from Aqueous Solutions

2020 ◽  
Author(s):  
Lorena Alcaraz ◽  
Dayana Nathaly Saquinga ◽  
Floralba López ◽  
Lola de Lima ◽  
Francisco J. Alguacil ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Crystallinity Index ◽  
Freundlich Isotherm ◽  
Order Kinetic ◽  
X Ray ◽  
Cellulose Structure ◽  
13C Nuclear Magnetic Resonance ◽  
Before And After ◽  
Pseudo Second Order

Preparation of a low-cost cellulose-based bioadsorbent from the cellulosic material extracted from the rose stems (CRS) was carried out; rose stems were considered agricultural wastes. After the required pretreatment of this waste, and its further treatment with an acidic mixture of acetic and nitric acids, the CRS product was yielded. The resulting bioadsorbent was characterized by several techniques, such as X-ray diffraction, which revealed diffraction maxima related to cellulose structure, whose calculated crystallinity index (CrI) was 75 %. In addition, Fourier Transform Infrared spectroscopy (FTIR), 13C Nuclear Magnetic Resonance (NMR), and X-ray Photoelectron Spectroscopy (XPS) showed signs of acetylation of the sample, also, the thermal properties of the solid was evaluated through Thermogravimetric Analysis (TGA). Scanning Electron Microscopy (SEM) showed cellulose fibers before and after the adsorption process, some particles with not regular shapes were also observed. The CRS bioadsorbent was used in the effective adsorption of valuable Tb(III) from aqueous solution. The adsorption data resulted in a better fit to the Freundlich isotherm, and pseudo-second-order kinetic models; however, chemisorption had not been ruled out. Finally, desorption experiments revealed a recovery of terbium ions with an efficiency of 97 % from terbium-loaded bioadsorbent.

scholarly journals Adsorption of reactive blue BF-5G dye on MCM-41 synthesized from Chocolate clay

Cerâmica ◽  
2020 ◽  
Vol 66 (379) ◽  
pp. 269-276
Author(s):  
L. N. R. de Paula ◽  
G. M. de Paula ◽  
M. G. F. Rodrigues
Keyword(s):  
Adsorption Equilibrium ◽  
Acid Leaching ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Order Model ◽  
Freundlich Model ◽  
X Ray ◽  
Silica Source ◽  
Pseudo Second Order ◽  
Mcm 41

Abstract The efficiency of as-synthesized and calcined mesoporous silica, using clay as a silica source, to remove the reactive blue BF-5G dye was investigated. The materials were characterized by X-ray diffraction (XRD) analysis, energy-dispersive X-ray fluorescence (ED-XRF), and Fourier-transform infrared spectroscopy. The kinetic and adsorption isotherms were also studied. The XRD and ED-XRF results showed that the Chocolate clay is rich in SiO2 (69.4%) and has a large amount of other oxides, which can be eliminated by acid leaching. According to the characterization results, the MCM-41 synthesis was effective and produced a highly-ordered material. The kinetic study showed the adsorption corresponded predominantly to the pseudo-second order model. Adsorption equilibrium was reached after 3 h, and the data were better fitted to the Freundlich model. Furthermore, both samples obtained satisfactory removal results, being potential adsorbents having reduced cost due to the use of an alternative silica source.

scholarly journals Preparation of KOH and H3PO4 Modified Biochar and Its Application in Methylene Blue Removal from Aqueous Solution

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 891 ◽  
Author(s):  
Li Liu ◽  
Yang Li ◽  
Shisuo Fan
Keyword(s):  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Textile Wastewater ◽  
Physical Interaction ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modified Biochar ◽  
Quality Of Water ◽  
Pseudo Second Order

Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H3PO4 (KOH-CSBC, H3PO4-CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H3PO4-CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H3PO4-CSBC was 43.14 mg g−1, 406.43 mg g−1 and 230.39 mg g−1, respectively. Chemical modification significantly enhanced the adsorption of MB onto biochar, especially for KOH-CSBC. The adsorption mechanism between MB and biochar involved physical interaction, electrostatic interaction, hydrogen bonding and π–π interaction. Hence, modified CSBC (especially KOH-CSBC) has the potential for use as an adsorbent to remove dye from textile wastewater.

Isotherm, Kinetics, and Adsorption Mechanism Studies of DTPA-Modified Banana/Pomegranate Peels as Efficient Adsorbents for Removing Cd(II) and Ni(II) from Aqueous Solution

2021 ◽  
Author(s):  
Fanghui Wang ◽  
Peng Wu ◽  
Lin Shu ◽  
Qingbin Guo ◽  
Di Huang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Adsorption Mechanism ◽  
Physical Adsorption ◽  
Order Model ◽  
X Ray ◽  
Synthetic Materials ◽  
Pseudo Second Order ◽  
Cost Efficient ◽  
First Time ◽  
Sewage Systems

Abstract Two novel absorbents were synthesized for the first time by banana and pomegranate peels using diethylenetriaminepentaacetic acid (DTPA) modification to eliminate Cd(II) and Ni(II) of sewage. The DTPA-modified peels performed significantly higher adsorption capacity than unmodified materials. Adsorption isotherm and kinetics models were simulated to determine their removal efficiency and potential for recovery of these two heavy metals. As the results, the adsorption reached equilibrium within 5 minutes and was well described by the pseudo-second order model and Langmuir isotherm. The surface morphology analysis of the synthetic materials by Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy, Fourier Transform Infrared spectroscopy and X-ray Photoelectron Spectroscopy, implied that ion exchange, complexation and physical adsorption may together contribute to Cd(II) and Ni(II) loading on DTPA-modified peels. This study demonstrates the feasibility of waste peels as cost-efficient bio-absorbents to remove Cd(II) and Ni(II) in sewage systems, and discovers potential adsorption mechanism of efficiency improvements after DTPA modification.

Removal of Cobalt (II) Ions from Aqueous Solution on Zinc(II) Ions Doping Chitosan/Hydroxyapatite Composite

2013 ◽  
Vol 22 (6) ◽  
pp. 096369351302200
Author(s):  
CunPing Liu
Keyword(s):  
Aqueous Solution ◽  
Precipitation Method ◽  
Batch Adsorption ◽  
Order Model ◽  
Isothermal Adsorption ◽  
Freundlich Model ◽  
X Ray ◽  
Hydroxyapatite Composite ◽  
Initial Ph ◽  
Pseudo Second Order

In the present investigation, bio-inorganic composite, which was synthesized with chitosan and hydroxyapatite by adding zinc(II) ions, have been prepared by precipitation method and was characterized by Fourier Transform infrared (FTIR) spectroscopy and energy dispersive X-ray analyzer (EDXA). Then, the composite was used for removal of Cobalt(II) from synthetic aqueous solution. The effects of initial pH, contact time, kinetic and isothermal adsorption were studied in detail using batch adsorption at different temperature. The results showed that Cobalt(II) ions can be efficiently removed and also demonstrated that the kinetic data were best described by the pseudo-second-order model (R2>0.99), While thermodynamic investigation of Cobalt(II) ions adsorption by zinc(II) doping Chitosan/hydroxyapatite (Zn-HAPCS) composite confirmed a spontaneous adsorption. Further investigations demonstrated that the adsorption pattern fitted well with Langmuir model (R2 > 0.99), but less-satisfied with Freundlich model (R2 < 0.95).

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