Development and Characterisation of Nanoclays from Indian Clays

Abstract

Indian clays are known for their smecticity. One such clay sample collected from Bhuj (Gujarat) was characterised and modified by successive sedimentation processes for different time intervals. The non-plastic components of clay, viz., quartz, illite, iron oxide, CaO, MgO, and organic matter were removed in different steps, as the heavy impurities in the clay-water suspensions, settle down during sedimentation. The free iron oxide present in clay suspension was reduced by giving sodium citrate-bicarbonate-dithionite treatment and iron content was further reduced from 1215 per cent to 57 per cent respectively. The organic matter was removed by sodium acetate-H 2 O 2 treatment. The modified clay so obtained was characterised by thermal analysis, FTIR, and XRD, SEM and TEM. The cation exchange capacities of original and modified clays were determined both by methylene blue method and ammonium acetate method. The cation exchange capacity is found to enhance from 120130 meq/100 g to 135145 meq/100 g. Using the above procedure, 92 per cent smecticity was obtained. Organophilisation of purified clay (smectite) was carried out by intercalation with alkyl ammonium salt. The XRD analysis showed enhancement of interlamellar spacing from 1.294 nm to 2.855 nm.

Carbon foam production from bio‐based polyols of liquefied spruce tree sawdust: Effects of biomass/solvent mass ratio and pyrolytic oil addition

“…The compression strengths of carbon foams produced without using bio‐oil vary between 0.225 and 0.295 MPa. Lower compressive strengths are related to lower crosslinking in polymer, larger cell size, hence, weak cell walls . Compressive strength values of foams without bio‐oil addition were well matched with the compressive strengths of the traditional phenolic foams (0.14–0.62 MPa) .…”

Morphological and Microstructural Characterization of Organoclays from Low Smectite Containing Clays Materials

“…All samples were pulverized, sieved (<200 µm), and stored in dry plastic bags prior to modification. HDTMA bromide (Sigma-Aldrich) was used to carry out the cation exchange reaction in the synthesis of the organoclays using the simple hydrothermal method [30,31], under very mild reaction conditions.…”

“…The DCB solution was removed by centrifugation and the clay samples washed severally until pH was 7. The treated clay samples were finally treated with hydrogen peroxide and sodium acetate solution to remove organic substances from the clay as explained in Manocha et al [31]. The treated samples were dried at 105ºC and labelled as Sample 1 and Sample 3 for Sample A and Sample C respectively.…”

“…Due to an isomorphic substitution within the layers, the clay mineral layer is negatively charged, which is counterbalanced by the exchangeable cations such as Na + , Ca 2+ in the interlayers [30]. The hydration of the inorganic exchange ions present in clays and the nature of Si-O groups impart a hydrophilic nature to the mineral surfaces and this property makes them easy to absorb water but very difficult to disperse in organic matrices and hence renders the clay ineffective for interaction with aliphatic and relatively hydrophobic compounds [31,32]. The most studied methods for solving this problem generally involve the replacement of these exchangeable cations with an organic group.…”

Preparation and Characterization of Carbon Foam Derived from Fine Coal and Phenolic Resin

“…Furthermore, the sample was weighed using the analytical balance (Ohaus pioneer) with a precision of 0.0001 g. Porosity values was calculated using Eq. 1 [16].…”