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The synthesis of carbon nanotubes (CNTs) by the chemical vapour deposition (CVD) method using natural calcite from Anadara granosa shells as the metal catalyst support was studied. Hexane and iron (Fe) were used as the carbon precursor and the active component of the catalyst, respectively. Response surface methodology (RSM) based on central composite design (CCD) was used to optimise the effect of total iron loading, the duration of reaction, and reaction temperature. The optimal conditions were total iron loading of 7.5%, a reaction time of 45 min, and a temperature of 850°C with a resulting carbon yield of 131.62%. Raman spectra, field-emission-scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses showed that the CNTs were of the multiwalled type (MWNTs). [ABSTRACT FROM AUTHOR]

The anion of hippuric acid, hippurate (Å), as an organic guest was intercalated into the interlayers of anionic clay, Zn/Al hydrotalcite-like or layered double hydroxides (LDH) host by direct co-precipitation method from aqueous solution for the formation of new nanohybrid compounds, Zn/Al-hippurate nanohybrids (ZAHs). Various Zn/Al molar ratios (R) = 3-5 and concentrations of HA (0.06-0.15 M) were used for the synthesis. ZAHs synthesized, using 0.15 M HA, was found to give well-ordered layered nanohybrid materials with an increase of the basal spacing to 19.6-21.0 Å compared to 8.8-9.0 Å in the LDHs. The increase in the basal spacing is due to the insertion of A- organic moiety into the LDH interlayers. Formation of the host-guest type of material was confirmed by XRD, FTIR, TGA/DTG and compositional analysis. The release of the intercalated guest was found to be tunable in a controlled manner by Zn/Al molar ratio and is governed by pseudo-second order kinetics. Thus, by varying the experimental conditions, the release property of the guest anion can be tailored as required. [ABSTRACT FROM AUTHOR]

Nanocomposites of Zn/Al-layered double hydroxide(anthraquinone-2,6-disulfonate) were synthesized by spontaneous direct assembly of inorganic and organic phases from aqueous solution. Powder X-ray diffraction patterns showed that a pure, single nanocomposite phase of good crystallinity was obtained using 1.0 M antraquinone-2,6-disulfonate ion (AQ26) and aging at 80 degrees C using conventional heating for 7 days or 0.5 h under microwave radiation, and these samples are denoted as ZAAN26C or ZAAN26MH, respectively. Zn/Al-nitrate-layered double hydroxide synthesized by a conventional method (ZANLC) showed a basal spacing of 8.3 A while both the nanocomposites showed 18.8 A as a result of AQ26 intercalation. FTIR study showed that the resulting nanocomposites are free from nitrate, the co-anion present in the mother liquor, indicating that only AQ26 is preferred during intercalation for the formation of the nanocomposite. The Brunauer, Emmet and Teller (BET) and micropore surface areas for ZAAN26C decreased relative to the ZANLC from 16.2 to 4.7 and 1.6 to 1.3 m2/g, respectively. These results indicate that AQ26 can be rapidly interdcalated in layered double hydroxide using microwave-aging resulting in a nanocomposite.