An overview of nanoclays or organically modified layered silicates (organoclays) is presented with emphasis placed on the use of nanoclays as the reinforcement phase in polymer matrices for preparation of polymer/layered silicates nanocomposites, rheological modifier for paints, inks and greases, drug delivery vehicle for controlled release of therapeutic agents, and nanoclays for industrial waste water as well as potable water treatment to make further step into green environment. A little amount of nanoclay can alter the entire properties of polymers, paints, inks and greases to a great extent by dispersing 1nm thick layered silicate throughout the matrices. The flexibility of interlayer spacing of layered silicates accommodates therapeutic agents which can later on be released to damaged cell. Because the release of drugs in drug-intercalated layered materials is controllable, these new materials have a great potential as a delivery host in the pharmaceutical field. The problem of clean water can be solved by treating industrial and municipal waste water with organoclays in combination with other sorbents like activated carbon and alum. Organoclays have proven to be superior to any other water treatment technology in applications where the water to be treated contains substantial amounts of oil and grease or humic acid.

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The present study focused on the hydrofluoric acid (HF) free synthesis of chromium based metal organic framework, MIL-101(Cr) and its application for hydrogen storage. MIL-101(Cr) has been synthesized hydrothermally using HF, acetic acid, perfluorobenzoic acid, and without acid. The characterization of the synthesized materials were carried out using powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and surface area (BET) by nitrogen adsorption isotherm at 77 K. The results demonstrated that acetic acid mediated synthesized MIL-101(Cr) exhibited higher surface area and pore volume than those synthesized with other organic acids. This may be due to the enhanced dissolution of terephthalic acid in the presence of acetic acid which facilitates the formation of MIL-101(Cr) nuclei during the synthesis. A comparison of conventional and HF free-synthesized MIL-101(Cr) for hydrogen adsorption capacity determined at 77 K up to 4500 kPa revealed that MIL-101(Cr) synthesized using acetic acid exhibited higher hydrogen adsorption capacity (5.6 wt %) than the MIL-101(Cr) synthesized with perfluorobenzoic acid (3.7 wt %) and without acid (4.8%). However, it is slightly less than the H 2 adsorption capacity of MIL-101(Cr) synthesized using HF (6.1 wt %). The higher H 2 adsorption capacity of MIL-101(Cr) synthesized using acetic acid can be attributed to the better terephthalate-chromium interaction which facilitates the formation of more crystalline product thereby creating more unsaturated metal centers in MIL-101(Cr). The present study suggested that acetic acid may be a suitable alternative for highly corrosive and hazardous HF which led to easier preparation of MIL-101(Cr) for the large-scale production and applications.

, hydrothermally synthesized and purified by solvent extraction, was used as adsorbent for the removal of nitrobenzene from aqueous solution. Pristine MIL-53(Al) and MIL-53(Al) loaded with various amounts of nitrobenzene were characterized by X-ray diffraction analysis with cell indexation study, thermogravimetric analysis, Fourier transform infrared spectroscopy, and BET surface area. A simulation study of nitrobenzene adsorption on MIL-53(Al) was performed. The adsorption study of nitrobenzene on MIL-53(Al) was carried out at 30 ( 1 °C using batch experiments. The amount of nitrobenzene adsorbed decreases with an increase in the temperature from 30°to 60 °C and pH from 8 to 11, whereas no significant difference was observed in acidic pH. The adsorption data were fitted to Sips and RedlichÀPeterson isotherm models. The adsorption capacity of nitrobenzene on MIL-53(Al) obtained was 610 mg/g, higher than that of zeolites (267.2 mg/g) and organoclays (100 mg/g), but, lower than that of modified commercial activated carbons (1443.53 mg/g).

The metal- and solvent-free single-step approach for the synthesis of carbon microspheres using various municipal plastic wastes at 700 °C under autogenic pressure is reported. The obtained carbon spheres have been characterized with different microscopic and spectroscopic techniques. The microscopic analysis showed formation of carbon microspheres having diameters of 1–8 μm. Among the different types of plastic wastes studied, only polyethylene, polypropylene, and polyacrylate could be converted into carbon spheres with 100% purity, whereas carbon particles with irregular shapes were also observed in the cases of other plastic wastes. The absence of catalyst makes the carbon spheres free from metal impurities and avoids the further purification process. The synthesis of carbon spheres from plastic wastes proceeds with the formation of aromatic hydrocarbons. The nanocrystalline CuO hollow spheres with a wall thickness of ∼130 nm have been prepared using plastic waste-derived carbon spheres as the template material under ultrasonic treatment.