scholarly journals Fe-based layered double hydroxides for removing arsenic from water: sorption–desorption–regeneration

2021 ◽  
Author(s):  
Tuğba Türk ◽  
Taha Boyraz ◽  
İbrahim Alp
Keyword(s):  
Aqueous Solution ◽  
Layered Double Hydroxides ◽  
Arsenic Removal ◽  
High Surface ◽  
High Surface Area ◽  
Exchange Capacity ◽  
Alkaline Solutions ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Double Hydroxides

Abstract Since the presence of arsenic in the waters of the world causes serious health effects on people, it is very important to remove it. Layered double hydroxides have a high surface area and high anion exchange capacity, and because of this feature, it is a potential adsorbent to remove arsenic. For regeneration and reuse of adsorbents, researchers in some limited studies have used agents such as acids and alkalis. Media replacement accounts for approximately 80% of the total operational and maintenance costs. In this paper, an adsorption/desorption/regeneration study was carried out with MgFeHT to determine the desorption properties of the adsorbent and to examine its reusability. The best alkaline desorption solution was determined from two different alkaline solutions: NaOH and KH2PO4. As(V) adsorption capacity of the MgFeHT at different pH (3–12) using the arsenic aqueous solution (with 2,000 μg As(V)/L) was evaluated. For the adsorption process, the experimental data are fitted well with the pseudo-second-order kinetic model and the Langmuir model. Moreover, the concentration of 2,000 μg/L arsenic was reduced to below the legal limit determined by the WHO (<10 μg/L). The regeneration studies were conducted on the adsorptive media used in the arsenic removal system. The regeneration efficiency of As(V) was maintained 98.5% for four regeneration cycles using 0.5 M NaOH. MgFeHT was successfully regenerated with an aqueous solution of NaOH and was reused with a small loss of sorption efficiency.

scholarly journals In situ synthesis of layered double hydroxides on γ-Al2O3 and its application in chromium(VI) removal

2017 ◽  
Vol 75 (6) ◽  
pp. 1466-1473 ◽  
Author(s):  
Shifeng Li ◽  
Fang Qi ◽  
Min Xiao ◽  
Hongtao Fan ◽  
Yanming Shen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Layered Double Hydroxides ◽  
Adsorptive Capacity ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Chromium Vi ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Double Hydroxides

Mg-Al layered double hydroxides (LDHs) adsorbent was synthesized in situ on γ-Al2O3 for the removal of Cr(VI) from aqueous solution. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electronic microscopy and thermogravimetry and differential thermal analysis. Compared to the LDHs powder, the calcined LDHs sorbent prepared in situ on γ-Al2O3 had higher specific surface area and was easy to recover and reuse. The adsorptive capacity for removing Cr(VI) from aqueous solution was resulting from the memory effect of LDHs based on the XRD results. Both the pseudo-second-order kinetic model and the Langmuir model fit the experimental data well. Furthermore, the adsorbent exhibits excellent sorption–regeneration performances.

scholarly journals Synthesis of Silver-Impregnated Magnetite Mesoporous Silica Composites for Removing Iodide in Aqueous Solution

Toxics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 175
Author(s):  
Sang-Eun Jo ◽  
Jung-Weon Choi ◽  
Sang-June Choi
Keyword(s):  
Aqueous Solution ◽  
Langmuir Isotherm ◽  
High Surface ◽  
High Surface Area ◽  
High Capacity ◽  
Maximum Adsorption Capacity ◽  
Initial Contact ◽  
Order Kinetic ◽  
Sorption Ability ◽  
High Sorption

Mag@silica-Ag composite has a high sorption ability for I− in aqueous solution due to its high surface area and strong affinity for the studied anion. The material adsorbed I− rapidly during the initial contact time (in 45 min, η = 80%) and reached adsorption equilibrium after 2 h. Moreover, mag@silica-Ag proved to selectively remove I− from a mixture of Cl−, NO3− and I−. The adsorption behavior fitted the Langmuir isotherm perfectly and the pseudo-second-order kinetic model. Based on the Langmuir isotherm, the maximum adsorption capacity of mag@silica-Ag was 0.82 mmol/g, which is significantly higher than previously developed adsorbents. This study introduces a practical application of a high-capacity adsorbent in removing radioactive I− from wastewaters.

scholarly journals Bifunctional acid–base mesoporous silica@aqueous miscible organic-layered double hydroxides

RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3749-3754 ◽  
Author(s):  
Hongri Suo ◽  
Haohong Duan ◽  
Chunping Chen ◽  
Jean-Charles Buffet ◽  
Dermot O'Hare
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Layered Double Hydroxides ◽  
High Surface ◽  
High Surface Area ◽  
Core Shell ◽  
Acid Base ◽  
Double Hydroxides ◽  
Hierarchical Morphology ◽  
Size And Structure

Core@shell materials which exhibit hierarchical morphology with ultra high surface area and controllable pore size and structure have been synthesised.

scholarly journals On the Active Adsorption of Chromium(III) from Alkaline Solutions Using Multi-Walled Carbon Nanotubes

2019 ◽  
Author(s):  
Francisco J. Alguacil ◽  
Félix A. López
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
Equilibrium Data ◽  
Order Kinetic Model ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The present investigation deals with the adsorption of chromium(III) from alkaline media using multi-walled carbon nanotubes. The adsorption of Cr(III) has been studied under various experimental conditions: stirring speed of the aqueous solution, initial metal and adsorbent concentrations, NaOH concentration in the aqueous solution, and temperature. The rate law indicated that chromium adsorption is well represented by the particle diffusion model, whereas the adsorption process fits to the pseudo-second order kinetic model within an exothermic character. Equilibrium data fit to the Langmuir type-2 equilibrium isotherm in an spontaneous process. Chromium(III) can be eluted from metal-loaded nanotubes using acidic solutions, from which fine chromium(III) oxide pigment can be ultimately yielded.

Synthesis of high surface area MgAl2O4 spinel as catalyst support via layered double hydroxides-containing precursor

2016 ◽  
Vol 132-133 ◽  
pp. 243-250 ◽  
Author(s):  
Dalin Li ◽  
Miaomiao Lu ◽  
Yunbing Cai ◽  
Yanning Cao ◽  
Yingying Zhan ◽  
...  
Keyword(s):  
Surface Area ◽  
Layered Double Hydroxides ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Mgal2o4 Spinel ◽  
Double Hydroxides

scholarly journals On the Active Adsorption of Chromium(III) from Alkaline Solutions Using Multiwalled Carbon Nanotubes

2019 ◽  
Vol 10 (1) ◽  
pp. 36 ◽  
Author(s):  
Francisco José Alguacil ◽  
Félix A. López
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Multiwalled Carbon Nanotubes ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Order Kinetic ◽  
Multiwalled Carbon ◽  
Experimental Conditions ◽  
Equilibrium Data ◽  
Order Kinetic Model

The present investigation deals with the adsorption of chromium(III) from alkaline media, as representative of highly-caustic component solutions of nuclear tank wastes, using multiwalled carbon nanotubes. The adsorption of Cr(III) has been studied under various experimental conditions, i.e., stirring speed of the aqueous solution, initial metal and adsorbent concentrations, NaOH concentration in the aqueous solution, and temperature. The rate law indicated that chromium adsorption is well represented by the particle diffusion model, whereas the adsorption process fits with the pseudo-second order kinetic model within an exothermic setting. Equilibrium data fit to the Langmuir type-2 equilibrium isotherm in a spontaneous process. Chromium(III) can be eluted from metal-loaded nanotubes using acidic solutions, from which fine chromium(III) oxide pigment can ultimately be yielded.

Synthesis and characterisation of aqueous miscible organic-layered double hydroxides

2014 ◽  
Vol 2 (36) ◽  
pp. 15102-15110 ◽  
Author(s):  
Chunping Chen ◽  
Miaosen Yang ◽  
Qiang Wang ◽  
Jean-Charles Buffet ◽  
Dermot O'Hare
Keyword(s):  
Surface Area ◽  
Layered Double Hydroxide ◽  
Layered Double Hydroxides ◽  
High Surface ◽  
High Surface Area ◽  
New Family ◽  
Double Hydroxide ◽  
Double Hydroxides

We report the synthesis and characterisation of a new family of high surface area and dispersible layered double hydroxides entitled Aqueous Miscible Organic Layered Double Hydroxide (AMO-LDH).

scholarly journals Ordered Mesoporous Carbons as Novel and Efficient Adsorbent for Dye Removal from Aqueous Solution

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Phuong T. Dang ◽  
Hoa T. H. Nguyen ◽  
Canh D. Dao ◽  
Giang H. Le ◽  
Quang K. Nguyen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
High Surface ◽  
High Surface Area ◽  
Soft Template ◽  
Order Kinetic ◽  
Mesoporous Carbons ◽  
Hard Template ◽  
Ordered Mesoporous Carbons ◽  
Ordered Mesoporous ◽  
Mb Adsorption

Ordered mesoporous carbons (OMCs) were successfully synthesized by using hard template and soft template methods. These materials were characterized by XRD, TEM, and N2adsorption-desorption Brunauer-Emmett-Teller (BET). From the obtained results, it is revealed that the obtained OMCs samples showed high surface area (>1000 m2/g) with high pore volume, mainly mesopore volume (1.2–2.4 cm3/g). Moreover, OMCs samples had similar structure of the SBA-15 silica and exhibited high MB adsorption capacity withqmof 398 mg·g−1for OMCs synthesis with hard template and 476 mg·g−1for OMCs synthesis with soft template, respectively. From kinetics investigation, it is confirmed that MB adsorption from aqueous solution obeys the pseudo-second-order kinetic equation.

Mg – Al layered double hydroxides in the dephosphotation of municipal effluents

2021 ◽  
Vol 5 ◽  
pp. 47-57
Author(s):  
T. T. Gorbacheva ◽  
◽  
D. V. Mayorov ◽  
N. V. Fokina ◽  
◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Solid Phase ◽  
Sorption Process ◽  
Order Kinetic ◽  
Phase Synthesis ◽  
Phosphate Ions ◽  
Order Kinetic Model ◽  
Treatment Facilities ◽  
Double Hydroxides ◽  
Regional Water

Experimental modeling of phosphates extraction from model solutions and sludge mixture of regional water treatment facilities is carried out. The sorbents used are Mg – Al layered double hydroxides obtained by method of solid-phase synthesis according to patented technology. The experimental data of the PO43– -ions sorption onto Mg – Al LDH most accurately describes by pseudo-first order kinetic model. The process of phosphate ions sorption onto hydroxide form Mg – Al LDH proceeds in a mixed diffusion mode, not only the outer surface of the material, but also the inner surface of the grains is involved in the sorption process. The sorption capacity of the hydroxide form is 49 mg P/g, which corresponds to the average level of phosphorus removal from wastewater achieved in world practice for synthesized analogues. The use of the oxide form obtained by materials calcination during 600 °С increases the efficiency of municipal effluents dephosphotation.

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