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Nanotechnology Applications in Diesel Fuels and Related Research Fields
Published in Ozcan Konur, Biodiesel Fuels, 2021
Deng et al. (2011) study the production of biodiesel from Jatropha oil catalyzed by a nanosized solid basic catalyst in a paper with 171 citations. They synthesize hydrotalcite-derived particles with an Mg:Al molar ratio of 3:1 by a co-precipitation method using urea as the precipitating agent, subsequently with a ‘microwave-hydrothermal treatment’, and followed by calcination at 773 K for 6 h. These particles were microsized mixed Mg/Al oxides, although actually they were nanosized. Because of their strong basicity, they use the nanoparticles further as a catalyst for biodiesel production from Jatropha oil after pretreatment. They perform the experiments with the solid basic catalyst in an ultrasonic reactor under different conditions. At the optimized condition, they obtain a biodiesel yield of 95.2%, and they observe that the biodiesel properties were close to those of the German standard. The catalyst could be reused eight times. They conclude that these nanocatalyts were instrumental for biodiesel production from Jatropha oils.
Biogeochemical Processes for Carbonation and Neutralization of Alkaline Mining Waste, Recycling and Waste Management
Published in Hossain Md Anawar, Vladimir Strezov, Abhilash, Sustainable and Economic Waste Management, 2019
Hossain Md Anawar, Md Zabed Hossain, Vladimir Strezov
When seawater is added to caustic bauxite residue, the pH of the mixture is reduced causing hydroxide, carbonate or hydroxycarbonate minerals to be precipitated (Palmer and Ray 2009). The concentration of various salt ions in seawater is 55% chlorine (Cl−), 30.6% sodium (Na+), 7.7% sulphate (SO4−2), 3.65% magnesium (Mg2+), 1.17% calcium (Ca2+), 1.13% potassium (K+) and 0.7% others (Rai et al., 2012; Rai et al., 2013b). Seawater neutralisation of the bauxite residue facilitates a significant reduction in pH and dissolved metal concentrations, through the precipitation of hydrotalcite-like compounds, calcite and aragonite (CaCO3) and some other Mg, Ca, and Al hydroxide and carbonate minerals. The hydrotalcite-like compounds also remove oxy-anions of transition metals through a combination of intercalation and adsorption of the anionic species on the external surfaces, where small anions are intercalated while larger organic molecules are adsorbed (Palmer and Ray, 2009).
2 Separation Thin Film Composite Membranes
Published in Stephen Gray, Toshinori Tsuru, Yoram Cohen, Woei-Jye Lau, Advanced Materials for Membrane Fabrication and Modification, 2018
Wang and coworkers developed a new membrane by constructing high-speed facilitated transport channels (i.e., hydrotalcite (HT)) in a fixed carrier membrane (e.g., PEI and PVAm based polymers) (Liao et al., 2014, 2015). Hydrotalcite is a type of layered double hydroxide, which consists of positively charged host layers that can readily accommodate hydrated carbonate anions moving through the interlayer channels. These channels thus enhance the CO2 facilitated transport properties. Figure 9.11 shows a schematic of the formation of the PEIE-HT complex, where PEIE is a polymer synthesized from PEI and epichlorohydrin. The resultant membrane possessed both fixed carrier sites from the polymer matrix and movable carrier sites in the interlayer of the HT. As a result, the CO2 permeance of the PEIE–HT membrane was 5693 GPU and the CO2/N2 selectivity was 268 at 110 kPa, which are 7 and 4 times of those of the PEIE membrane, respectively.
Ozonation Catalyzed by CoxFe1 Layered Double Hydroxide for the Degradation of P-toluenesulfonic Acid
Published in Ozone: Science & Engineering, 2021
Xiaojie Fu, Yuanxing Huang, Yaowei Wang, Manli Liang, Ya Yang, Zhihao Jin, Junhao Yang, Shouxun Hu, Liang Li
Layered doubled hydroxide (LDH) is the general term of hydrotalcite and hydrotalcite-like compound. LDH is a compound assembled from positively charged main laminates and interlaminar anions through the interaction of noncovalent bonds. Its structure is similar to Mg (OH) 2 and the unit layer is formed by the shared edge of MgO6 octahedron. It has the following outstanding characteristics: (1) the chemical composition of the main laminate is adjustable; (2) the type and number of guest anions between layers can be adjusted; (3) particle size and distribution of intercalated assembly can be regulated (Li et al. 2015). Generally speaking, as long as the metal cation has an appropriate ion radius and charge number, LDHs laminar can be formed. Its chemical composition can be expressed as: the M2+ includes Mg2 +, Ni2 +, Co2 +, Zn2 +, Cu2 +, etc. the M3+ includes Al3 +, Cr3 +, Fe3 +, Sc3 + etc. An- is anion, such as CO32-, NO3−, Cl −, OH−, SO42-, PO43-, C6H4 (COO)22-. When the molar ratio () is between 0.17 and 0.33, the LDHs having complete structure can be obtained (Dai et al. 2014; Farias, Paula-Silva, and Almeida-Val 1997; Sable, Medina, and Contreras 2014).
Green synthesis of hydrotalcite from untreated magnesium oxide and aluminum hydroxide
Published in Green Chemistry Letters and Reviews, 2018
F. J. W. J. Labuschagné, A. Wiid, H. P. Venter, B. R. Gevers, A. Leuteritz
Layered double hydroxides (LDHs) are layered anionic clays with the general formula with [] describing the composition of the LDH layers consisting of trivalent (MIII) and divalent (MII) metal cations, and [] representing the composition of the anionic interlayer (1, 1021). Hydrotalcite is a naturally occurring LDH form with the formula Mg6Al2(OH)16CO3·4H2O (2). In its synthetic form, hydrotalcite can exist in Mg:Al ratios ranging from 1:1 to 3:1 (1, 1024). Hydrotalcite has a wide range of applications which include the use as polymer stabilizers, flame-retardants for polymers and anion scavengers (3; 4; 5; 6) as well as a wide range of environmental applications which are comprehensively discussed in the Handbook of Clay Science (7) and include applications as basic catalysts and water purification agents.
Mg/Al/Zr hydrotalcite like compounds as catalysts for green synthesis of carbamates
Published in Inorganic and Nano-Metal Chemistry, 2022
Marwa Aloui, Rihem Dardouri, Salwa B. Ghorbel, Mayra G. Álvarez, Francisco Medina, Mongia S. Zina
The synthesis of carbamates from amines, alcohols and carbon dioxide is currently presented as an attractive route and still remains a challenging goal.[9,10] In fact, the use of amines, carbon dioxide, and electrophilic substrates for the synthesis of carbamates has been reported since the 90 s. This approach lies on the production of the carbamate anion from the reaction of carbon dioxide with a primary or secondary amine which further reacts with an electrophylic alkyl source. Alkyl halides are commonly used as the electroplilic alkyl source because of its good reactivity; however, the use of alcohols as electrophyle is preferable against an alkyl halide to avoid the formation of corrosive by-products (e.g., HCl). In this regard, very few reports have appeared addressing the production of carbamates from carbon dioxide, amine and alcohols. For instance, Abla et al.[11] reported high yields of carbamate through a phosgene-free-halogen-free synthetic route using a Ni-phenanthroline complex as homogenous catalyst. Ion et al.[6]also reported the use of soluble Cs2CO3 and Rb2CO3 as promising basic catalysts toward the carbamate product in appreciable yield, as well as the use of solid heterogeneous basic catalyst such as KF/Al2O3 being the only publication (to the best of the authors' knowledge) regarding the use of heterogeneous basic catalysts in this reaction. Among the widely used heterogeneous catalysts, hydrotalcites are well known to be highly versatile basic catalysts.