scholarly journals A Comparison among Synthetic Layered Double Hydroxides (LDHs) as Effective Adsorbents of Inorganic Arsenic from Contaminated Soil–Water Systems

Soil Systems ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 37
Author(s):  
Massimo Pigna ◽  
Antonio Violante ◽  
Antonio Giandonato Caporale

The need for cost-effective adsorbents of inorganic arsenic (As(III) and As(V)) stimulates the academia to synthesize and test novel materials that can be profitably applied at large-scale in most affected areas worldwide. In this study, four different layered double hydroxides (Cu-Al-, Mg-Al-, Mg-Fe- and Zn-Al-LDH), previously synthesized and studied for As(III) removal capacity, were evaluated as potential adsorbents of As(V) from contaminated systems, in absence or presence of common inorganic anions (Cl−, F−, SO42−, HCO3− and H2PO4−). The As(V) desorption by H2PO4− was also assessed. Lastly, the As(V) adsorption capacities of the four layered double hydroxides (LDHs) were compared with those observed with As(III) in a complementary paper. All the LDHs adsorbed higher amounts of As(V) than As(III). Fe-Mg-LDH and Cu-Al-LDH showed higher adsorption capacities in comparison to Mg-Al-LDH and Zn-Al-LDH. The presence of competing anions inhibited the adsorption of two toxic anions according to the sequence: Cl− < F− < SO42− < HCO3− < < H2PO4−, in particular on Mg-Al-LDH and Zn-Al-LDH. The kinetics of As(V) desorption by H2PO4− indicated a higher occurrence of more easily desorbable As(V) on Zn-Al-LDH vs. Cu-Al-LDH. In conclusion, synthetic Cu- and Fe-based LDHs can be good candidates for an efficient removal of inorganic As, however, further studies are necessary to prove their real feasibility and safety.

2020 ◽  
Vol 4 (3) ◽  
pp. 53
Author(s):  
Karen Maria Dietmann ◽  
Tobias Linke ◽  
Markus Reischer ◽  
Vicente Rives

Nowadays, the contamination of groundwater and soils by highly hazardous and toxic chlorinated solvents is a global issue. Over the past years, different remediation strategies have been developed, involving injection of reactive solutions and/or particles. However, a major difficulty is the monitoring of injected particles during the injection and after secondary mobilisation by groundwater flow. This study is focussed on the development of directly traceable particles by combining fluorescein with Layered Double Hydroxides (LDHs). We present here the facile and easily tuneable synthesis of fluorescing LDHs (Fluo-LDH) via co-precipitation under supersaturation conditions. Their ability to mimic particle sizes of previously studied reactive LDHs, which proved to be able to adsorb or degrade chlorinated organic solvents from aqueous solutions, was investigated as well. Tests using a novel Optical Image Profiler (OIP) confirmed that the fluorescent LDHs can be easily detected with this tool. Even LDHs with the lowest amount of fluorescent dye were detectable. Together with the use of an OIP, which is capable of exciting the fluorescent material and collecting real-time pictures, this can provide a new, efficient, and cost-effective method for in situ tracing of injected particles in the subsurface.


2021 ◽  
Author(s):  
Yuying Hu ◽  
Susu Liu ◽  
Min Qiu ◽  
Xiaohuan Zheng ◽  
Xiaoming Peng ◽  
...  

Abstract Ly @ FeZn layered double hydroxides (LDHs) controllable fabrication based on Box-Behnken Design (BBD) model was fabricated, and presented stable and efficient removal performance for Ciprofloxacin (CIP), Norfloxacin (NOR) and Ofloxacin (OFL) removal. It should be noted that Ly @ FeZn had different adsorption behavior towards CIP, NOR and OFL. Furthermore, the Ly @ FeZn was characterized by SEM, XRD, FT-IR and XPS. Results revealed the optimized fabrication condition (temperature of 60 °C, Fe / Zn molar ratio of 0.5 and the lysine dosage of 5.8 mmol) for the removing efficient. The highest adsorption capacity of CIP, NOR and OFL were 193.83, 190.20 and 62.12 mg/g, respectively. Adsorption kinetics of both CIP and NOR were well simulated with the pseudo-first-order kinetic model, while that of OFL was well-described by the pseudo-second-order. Moreover, the adsorption thermodynamics of CIP and NOR on Ly @ FeZn indicated that the adsorption processes were exothermal, feasible and spontaneous. It was worth noting that the adsorption mechanism of Ly @ FeZn for CIP and NOR were the synergistic reaction of electrostatic attraction, chemical bonding and flocculation. On the other side, the adsorption behavior of OFL was relatively low, and the adsorption mechanism was only electrostatic attraction.


2009 ◽  
Vol 21 (24) ◽  
pp. 5809-5818 ◽  
Author(s):  
Jaime S. Valente ◽  
Manuel Sánchez-Cantú ◽  
Enrique Lima ◽  
François Figueras

2021 ◽  
pp. 127613
Author(s):  
Jiahui Ge ◽  
Lili Lian ◽  
Xiyue Wang ◽  
Xueling Cao ◽  
Wenxiu Gao ◽  
...  

2016 ◽  
Vol 123 ◽  
pp. 134-140 ◽  
Author(s):  
Facui Yang ◽  
Shiqi Sun ◽  
Xiaoqi Chen ◽  
Yue Chang ◽  
Fei Zha ◽  
...  

2015 ◽  
Vol 60 (2) ◽  
pp. 1357-1359 ◽  
Author(s):  
Y. Hongbo ◽  
C. Meiling ◽  
W. Xu ◽  
G. Hong

Abstract The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.


2016 ◽  
Vol 56 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Guillermo Puerta-Falla ◽  
Magdalena Balonis ◽  
Gabriel Falzone ◽  
Mathieu Bauchy ◽  
Narayanan Neithalath ◽  
...  

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