scholarly journals Exploring the Wet Mechanochemical Synthesis of Mg-Al, Ca-Al, Zn-Al and Cu-Al Layered Double Hydroxides from Oxides, Hydroxides and Basic Carbonates

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 954 ◽  
Author(s):  
Brenda Antoinette Barnard ◽  
Frederick Johannes Willem Jacobus Labuschagné

The synthesis of Mg-Al, Ca-Al, Zn-Al and Cu-Al layered double hydroxides (LDHs) was investigated with a one-step wet mechanochemical route. The research aims to expand on the mechanochemical synthesis of LDH using a mill designed for wet grinding application. A 10% slurry of solids was added to a Netzsch LME 1 horizontal bead mill and milled for 1 h at 2000 rpm. Milling conditions were selected according to machine limitations and as an initial exploratory starting point. Precursor materials selected consisted of a mixture of oxides, hydroxides and basic carbonates. Samples obtained were divided such that half was filtered and dried at 60 °C for 12 h. The remaining half of the samples were further subjected to ageing at 80 °C for 24 h as a possible second step to the synthesis procedure. Synthesis conditions, such as selected precursor materials and the MII:MIII ratio, were adapted from existing mechanochemical methods. LDH synthesis prior to ageing was successful with precursor materials observably present within each sample. No Cu-Al LDH was clearly identifiable. Ageing of samples resulted in an increase in the conversion of raw materials to LDH product. The research offers a promising ‘green’ method for LDH synthesis without the production of environmentally harmful salt effluent. The synthesis technique warrants further exploration with potential for future commercial up-scaling.

2016 ◽  
Vol 31 ◽  
pp. 409-416 ◽  
Author(s):  
Márton Szabados ◽  
Rebeka Mészáros ◽  
Szabolcs Erdei ◽  
Zoltán Kónya ◽  
Ákos Kukovecz ◽  
...  

2020 ◽  
Author(s):  
Bianca Gevers ◽  
Sajid Naseem ◽  
Charles Sheppard ◽  
Andreas Leuteritz ◽  
Johan Labuschagne

<div>Layered double hydroxides (LDHs) with high and tailorable UV-Vis-NIR absorption were prepared through transition</div><div>metal (TM) modification. The synthesis method used and amount of TM present were found to influence the UV-Vis-</div><div>NIR absorption intensity, -range, and the optical bandgap.</div><div><div>It was found that the incorporation of TMs in MgAl-LDH results in the existence of a "UV-Vis-NIR absorption fingerprint", the intensity of which can be tuned by the amount of TM present. There also exist differences in the UV-Vis-NIR absorption spectra and bandgaps obtained for MgAl-LDH synthesised using different synthesis conditions and methods, but these are not as visible when including transition metals. Further, the materials exhibit very complex spectra for which adequate explanation is lacking in literature. Finally, standard methods to determine the bandgap of materials, did not give conclusive results for all materials, only for some, and indicate that some of the materials might have multiple different transition types.</div></div>


2018 ◽  
Vol 9 ◽  
pp. 2980-2988 ◽  
Author(s):  
Qian Zhang ◽  
Qiyu Gu ◽  
Fabrice Leroux ◽  
Pinggui Tang ◽  
Dianqing Li ◽  
...  

An elegant and efficient approach consisting in the co-intercalation of stabilizing molecular anions is described here. The thermal stabilizer calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate] (Irganox 1425, MP-Ca) and a photo-oxidation stabilizer (hindered amine light stabilizer, HALS) are co-intercalated into the interlayer regions of layered double hydroxides (LDH) in a one-step coprecipitation. These hybrid organic–inorganic materials are successively dispersed in polypropylene to form H n M n ′-Ca2Al/PP composite films (with H = HALS and M = MP) through a solvent casting method. The corresponding crystalline structure, chemical composition, morphology as well as the resistance against thermal aging and photo-oxidation are carefully investigated by various techniques. The results show that the powdered H n M n ′-Ca2Al-LDHs hybrid materials have a much higher thermal stability than MP-Ca and HALS before intercalation. In addition, the H n M n ′-Ca2Al/PP composites exhibit a higher overall resistance against thermal degradation and photo-oxidation compared to LDHs intercalated with only HALS or MP. This underlines the benefit of the co-intercalation. The co-intercalated LDH materials pave a new way in designing and fabricating high-performance multifunctional additives for polymers.


2019 ◽  
Vol 55 (62) ◽  
pp. 9212-9215 ◽  
Author(s):  
Jiang Han ◽  
Gen Chen ◽  
Xiaohe Liu ◽  
Ning Zhang ◽  
Shuquan Liang ◽  
...  

Co3FePx/C nanocomposites were derived from one-step phosphorization of anthraquinone-2-sulfonate (AQS2) intercalated Co3Fe layered double hydroxides (Co3Fe LDHs).


Sign in / Sign up

Export Citation Format

Share Document