scholarly journals Simultaneous removal of fluoride and arsenic in geothermal water in Tibet using modified yak dung biochar as an adsorbent

2018 ◽  
Vol 5 (11) ◽  
pp. 181266 ◽  
Author(s):  
Luo Chunhui ◽  
Tian Jin ◽  
Zhu Puli ◽  
Zhou Bin ◽  
Bu Duo ◽  
...  
Keyword(s):  
Removal Rate ◽  
Energy Dispersive Spectrometer ◽  
Biomass Energy ◽  
Geothermal Water ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Order Kinetic Model ◽  
High Concentrations ◽  
Yak Dung

Fluoride (F) and arsenic (As) are two typical and harmful elements that are found in high concentrations in geothermal water in Tibet. In this work, yak dung, an abundant source of biomass energy in Tibet, was made into biochars (BC1, BC2 and BC3) by pyrolysis under different conditions, and the better biochar was modified by FeCl 2 (Fe-BC3). The adsorption conditions were optimized to adsorb F and As in geothermal water. The results showed that BC3 can remove 90% F − and 20% As(V), which is the best effect of the three initial biochars. Fe-BC3 could remove 94% F − and 99.45% As(V) under the same conditions as BC3, which was an adsorbent dosage 10 g l −1 , pH 5–6 and temperature of 25°C. It was also demonstrated that the removal rate did not decrease at 80°C. A quasi-second-order kinetic model best described the adsorption behaviour of ions on the surface of the biochar. The maximum adsorption capacity of F − and As(V) on Fe-BC3 was 3.928 mg g −1 and 2.926 mg g −1 , respectively. The features of Fe-BC3 were characterized by X-ray diffraction, Fourier transform infrared, Brunauer–Emmett–Teller, energy-dispersive spectrometer and scanning electron microscopy to understand the adsorption process.

scholarly journals Insights into Starch Coated Nanozero Valent Iron-Graphene Composite for Cr(VI) Removal from Aqueous Medium

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Prasanna Kumarathilaka ◽  
Vimukthi Jayaweera ◽  
Hasintha Wijesekara ◽  
I. R. M. Kottegoda ◽  
S. R. D. Rosa ◽  
...  
Keyword(s):  
Point Of Zero Charge ◽  
Inert Material ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Graphene Composite ◽  
Removal Capacity ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
First Time

Embedding nanoparticles into an inert material like graphene is a viable option since hybrid materials are more capable than those based on pure nanoparticulates for the removal of toxic pollutants. This study reports for the first time on Cr(VI) removal capacity of novel starch stabilized nanozero valent iron-graphene composite (NZVI-Gn) under different pHs, contact time, and initial concentrations. Starch coated NZVI-Gn composite was developed through borohydrate reduction method. The structure and surface of the composite were characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and point of zero charge (pHpzc). The surface area and pHpzc of NZVI-Gn composite were reported as 525 m2 g−1 and 8.5, respectively. Highest Cr(VI) removal was achieved at pH 3, whereas 67.3% was removed within first few minutes and reached its equilibrium within 20 min obeying pseudo-second-order kinetic model, suggesting chemisorption as the rate limiting process. The partitioning of Cr(VI) at equilibrium is perfectly matched with Langmuir isotherm and maximum adsorption capacity of the NZVI-Gn composite is 143.28 mg g−1. Overall, these findings indicated that NZVI-Gn composite could be utilized as an efficient and magnetically separable adsorbent for removal of Cr(VI).

scholarly journals Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

2018 ◽  
Vol 5 (3) ◽  
pp. 171927 ◽  
Author(s):  
Yong Fu ◽  
Yue Huang ◽  
Jianshe Hu
Keyword(s):  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Adsorption Behaviour ◽  
X Ray Diffraction ◽  
Mesoporous Composite ◽  
Adsorption Temperature ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Enthalpy And Entropy ◽  
Mcm 41

A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer–silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller measurements. The results showed that the CMP possessed multifunctional groups such as –OH, –COOH and –NH 2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l −1 , 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g −1 . According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption.

scholarly journals Ultra-efficient Copper Ions Adsorption of Chitosan-montmorillonite Composite Aerogel for Wastewater Treatment

2021 ◽  
Author(s):  
Xin Ye ◽  
Sisi Shang ◽  
Yifan Zhao ◽  
Sheng Cui ◽  
Ya Zhong ◽  
...  
Keyword(s):  
Copper Ions ◽  
Removal Rate ◽  
Three Dimensional ◽  
High Specific Surface Area ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Two Dimensional ◽  
Composite Aerogel ◽  
Order Kinetic Model ◽  
And Performance

Abstract The modified montmorillonite(MMT) has a two-dimensional stable and ordered lamellar structure. The addition of chitosan(CS) cross-links the two-dimensional sheets to build a three-dimensional network structure with a high specific surface area. We have prepared the best MMT-based water treatment materials that have been reported. This new type of aerogel can efficiently adsorb heavy metal ions in wastewater. The structure and performance of the composite material were characterized in this article. Besides, the adsorption kinetics, adsorption thermodynamics, pH influence, and recycling performance are all focused on. The adsorption equilibrium time of CS-MMT2 is 50 min. The removal rate of Cu2+ is as high as 98.21%. The maximum adsorption capacity is 86.95 mg/g. The adsorption process of Cu2+ by CS-MMT composite aerogel conforms to the quasi-second-order kinetic model and the Langrangian adsorption isotherm. After three cycles, the removal rate of Cu2+ by CS-MMT2 remained above 80%. This article also involves the discussion of the material's adsorption mechanism for Cu2+. This is a kind of environmentally friendly material that can be mass-produced, cheap, efficient, and excellent, which is of great significance to the development of environmental protection.

scholarly journals The study on adsorption behavior of 2,4-DCP in solution by biomass carbon modified with CTAB-KOH

2020 ◽  
Vol 82 (8) ◽  
pp. 1535-1546
Author(s):  
Dajun Ren ◽  
Hongyan Yu ◽  
Jian Wu ◽  
Zhaobo Wang ◽  
Shuqin Zhang ◽  
...  
Keyword(s):  
Removal Rate ◽  
Surface Group ◽  
Order Kinetic ◽  
Biomass Carbon ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Before And After ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Ft Ir

Abstract In this study, rice straw was used to prepare biomass carbon, which was modified with KOH and cetyltrimethylammonium bromide (CTAB) to obtain modified biomass carbon (MBC). The biomass carbon (BC) before and after modification was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR), and the surface morphology, crystal structure and surface group characteristic BC were explored. The specific surface area and micropores of the modified biomass carbon increased significantly, the crystallinity was higher, and the pore structure was more clearly found. The adsorption performance of MBC for 2,4-dichlorophenol (2,4-DCP) was investigated. The results showed that under the best adsorption conditions ((2,4-DCP concentration (200 mg/L), MBC dosage (50 mg), pH (5.5), and loading time (60 min), temperature (room temperature)), the removal rate of 2,4-DCP was up to 42.5%, and adsorption capacity was 85.13 mg/g. The adsorption of 2,4-DCP on MBC materials was better explained by the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. It was believed that the adsorption of 2,4-DCP by MBC was the monolayer adsorption process on the uniform surface of MBC at high concentration, and there was no interaction between the 2,4-DCP and MBC adsorbate during this process.

scholarly journals Removal of Cr(VI) from Aqueous Solution by Polypyrrole/Hollow Mesoporous Silica Particles

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 686 ◽  
Author(s):  
Linlin Du ◽  
Peng Gao ◽  
Yuanli Liu ◽  
Tsuyoshi Minami ◽  
Chuanbai Yu
Keyword(s):  
Mesoporous Silica ◽  
Binary Systems ◽  
In Situ Polymerization ◽  
Removal Rate ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Langmuir Isotherm Model ◽  
Hollow Mesoporous Silica

The removal of Cr(VI) in wastewater plays an important role in human health and environment. In this work, polypyrrole/hollow mesoporous silica particle (PPy/HMSNs) adsorbents have been newly synthesized by in-situ polymerization, which prevent the aggregation of pyrrole in the process of polymerization and exhibit highly selective and powerful adsorption ability for Cr(VI). The adsorption process was in good agreement with the quasi-second-order kinetic model and the Langmuir isotherm model. And the maximum adsorption capacity of Cr(VI) was 322 mg/g at 25 °C. Moreover, the removal rate of Cr(VI) by PPy/HMSNs was ~100% in a number of binary systems, such as Cl−/Cr(VI), NO3−/Cr(VI), SO42−/Cr(VI), Zn2+/Cr(VI), Fe3+/Cr(VI), Sn4+/Cr(VI), and Cu2+/Cr(VI). Thus, the PPy/HMSNs adsorbents have great potential for the removal of Cr(VI) in wastewater.

scholarly journals Preparation of new diatomite–chitosan composite materials and their adsorption properties and mechanism of Hg(II)

2017 ◽  
Vol 4 (12) ◽  
pp. 170829 ◽  
Author(s):  
Yong Fu ◽  
Xiaoxu Xu ◽  
Yue Huang ◽  
Jianshe Hu ◽  
Qifan Chen ◽  
...  
Keyword(s):  
Adsorption Isotherm ◽  
Kinetic Model ◽  
Contact Time ◽  
Ph Value ◽  
Raw Materials ◽  
Removal Rate ◽  
Adsorption Properties ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Order Kinetic Model

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet–visible (UV–Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g −1 .

Removal of hexavalent chromium from aqueous solution by calcined Zn/Al-LDHs

2016 ◽  
Vol 74 (1) ◽  
pp. 229-235 ◽  
Author(s):  
Hui-Duo Yang ◽  
Yun-Peng Zhao ◽  
Shi-Feng Li ◽  
Xing Fan ◽  
Xian-Yong Wei ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Precipitation Method ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Effects Of Ph ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Co Precipitation ◽  
Double Hydroxides

In this study, Zn/Al-layered double hydroxides (Zn/Al-LDHs) were synthesized by a co-precipitation method and characterized with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the hexavalent chromium Cr(VI) adsorption experiments on calcined Zn/Al-LDHs were carried out to analyze the effects of pH, temperature, adsorption time, initial Cr(VI) concentration and adsorbent dosage on the removal of Cr(VI) from aqueous solutions. The maximum adsorption capacity for Cr(VI) on calcined Zn/Al-LDHs under optimal conditions was found to be over 120 mg/g. The kinetic and isotherm of Cr(VI) adsorption on calcined Zn/Al-LDHs can be described with the pseudo-second-order kinetic model and Langmuir isotherm, respectively.

Adsorption of fluoride on a chitosan-based magnetic nanocomposite: equilibrium and kinetics studies

2018 ◽  
Vol 19 (1) ◽  
pp. 40-51 ◽  
Author(s):  
Abdolreza Abri ◽  
Mahmood Tajbakhsh ◽  
Ali Sadeghi
Keyword(s):  
Magnetic Nanocomposite ◽  
Ion Concentration ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Equilibrium And Kinetics ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Defluoridation Of Water

Abstract A new derivative of chitosan functionalized with chloroacyl chloride and 2-(2-aminoethylamino) ethanol was synthesized for the preparation of a magnetic nanocomposite containing Fe3O4@TiO2 nanoparticles. Characterizations were done by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The nanocomposite was examined for the defluoridation of water, and the effect of contact time, pH, initial fluoride ion concentration, and adsorbent dosage were investigated. The Langmuir model showed the best agreement with the experimental data. The maximum adsorption capacity for the fluoride removal from aqueous solutions was 15.385 mg/g at 318 K and pH = 5.0. The adsorption mechanism matches the pseudo-second-order kinetic model with a rate constant (k2) of 0.68 g/mg·min. The thermodynamics study of the nature of adsorption showed that ΔH and ΔS were 13.767 kJ/mol and 0.066 kJ/mol·K respectively. A mechanism for the fluoride sorption was proposed by considering the electrostatic and hydrogen bonding interactions.

scholarly journals Fabrication of the magnetic mesoporous silica Fe-MCM-41-A as efficient adsorbent: performance, kinetics and mechanism

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yige Guo ◽  
Bin Chen ◽  
Ying Zhao ◽  
Tianxue Yang
Keyword(s):  
Mesoporous Silica ◽  
Zero Valent Iron ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Environment And Health ◽  
Transmission Electron ◽  
Order Kinetic Model ◽  
Neutral Conditions ◽  
Magnetic Mesoporous Silica ◽  
Mcm 41

AbstractAntibiotics are emerging pollutants and increasingly present in aquaculture and industrial wastewater. Due to their impact on the environment and health, their removal has recently become a significant concern. In this investigation, we synthesized nano zero-valent iron-loaded magnetic mesoporous silica (Fe-MCM-41-A) via precipitation and applied the adsorption of oxytetracycline (OTC) from an aqueous solution. The effects of competing ions such as Na+, Ca2+ and Cu2+ on the adsorption process under different pH conditions were studied in depth to providing a theoretical basis for the application of nanomaterials. The characterization of the obtained material through transmission electron microscopy demonstrates that the adsorbent possesses hexagonal channels, which facilitate mass transfer during adsorption. The loaded zero-valent iron made the magnetic, and was thus separated under an applied magnetic field. The adsorption of OTC onto Fe-MCM-41-A is rapid and obeys the pseudo-second-order kinetic model, and the maximum adsorption capacity of OTC is 625.90 mg g−1. The reaction between OTC and Fe-MCM-41-A was inner complexation and was less affected by the Na+. The effect of Ca2+ on the adsorption was small under acidic and neutral conditions. However, the promotion effect of Ca2+ increased by the increase of pH. Cu2+ decreased the removal efficiencies continuously and the inhibitory effects decrease varied with the increase of pH. We propose that surface complexing, ion-exchange, cationic π-bonding, hydrogen bonding, and hydrophobicity are responsible for the adsorption of OTC onto Fe-MCM-41-A.

scholarly journals Phenol adsorption from wastewater using cashew nut shells as adsorbent

2018 ◽  
Vol 7 (3) ◽  
pp. 966
Author(s):  
Kartik Kulkarni ◽  
Varsha Sudheer ◽  
C R Girish
Keyword(s):  
Agricultural Waste ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Multilayer Adsorption ◽  
Phenol Adsorption ◽  
Cashew Nut ◽  
Experimental Parameters ◽  
Order Kinetic Model

The potential of agricultural waste cashew nut shells as an adsorbent for removing phenol from wastewater is presented in this paper. The adsorbent was treated with 3M sulphuric acid in order to improve the properties. The experimental parameters such as adsorbent dosage, concentration and temperature were optimized with response surface methodology (RSM). The isotherm data were tested with different isotherm models and it obeyed Freundlich Isotherm showing the multilayer adsorption. The kinetic data satisfied pseudo-first order kinetic model. The maximum adsorption capacity was calculated to be 35.08 mg/g proving the capability of cashew nut shells for removing phenol from wastewater.  

Sign in / Sign up

Export Citation Format

Share Document