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Analytical Research Laboratory, Department of Chemistry, University of Delhi, Delhi-110 007, India E-mail : monikadatta_chem@yahoo.co.in In the present work Montmorillonite (Mt) has been explored as a drug delivery vehicle for an antibiotic drug, Metronidazole (MTZ). The drug Mt interaction has been studied as a function of pH of the aqueous drug solution, contact time and initial drug concentration in the solution. The synthesized Mt-MTZ complex has been characterized using various appropriate analytical techniques. The in vitro release of MTZ from the synthesized Mt-MTZ complex in the simulated gastric fluid has been observed to provide more retention than the pure drug and the commercially available tablets. In the simulated intestinal fluid Mt-MTZ complex has been observed to provide better extended release of MTZ as compared to the pure drug and the commercially available tablets. The synthesized Mt-MTZ complex is more acidic resistant and provides an increase bioavailability in the intestinal fluid over an extended period of 12 h. The synthesized Mt-MTZ complex is likely to provide about three times more bioavailability of the drug as compare to pure MTZ.

Batch adsorption studies were carried out to investigate the adsorption behaviour of textile dye- reactive red 2 (RR2) from aqueous solution onto montmorillonite (Mt) clay and organophilic Mt clays. The monovalent organic cations- cetyltrimethylammonium (CTA+) and cetylpyridinium (CP+) were exchanged for the metal cations in montmorillonite clay to prepare the organophilic Mt clays- CTA–Mt and CP-Mt. The synthesis of these organophilic clays was confirmed by X-Ray diffraction (XRD), Fourier Transformed Infra Red (FTIR), specific surface area (BET ) and zeta potential techniques. The adsorption affinity of Mt, CTA-Mt and CP-Mt for RR2 was investigated as a function of initial dye concentration, pH of the aqueous dye solution, contact time and adsorbent dosage. The adsorption data obtained was fitted to the Langmuir, Freundlich and Temkin adsorption models and it was found that Langmuir adsorption isotherm yielded the most favourable representation of the adsorption behaviour of RR2. The adsorption kinetics of RR2 has been studied in terms of pseudo-first-order, pseudo-second-order and intraparticle diffusion processes. It was found that the pseudo-second-order mechanism is predominant in the present adsorption system suggesting chemisorption of the dye., European Chemical Bulletin, Vol 3, No 8 (2014): European Chemical Bulletin

Triarylmethane dyes have been identified as one of the toxic dyes. The presence of triarylmethane dyes in water act as pollutant and cause hazardous effect on natural resources, aquatic life as well as to human being. Triarylmethane dyes are extensively used for wool, silk, cotton, leather and paper industries. In the present work, natural sand has been utilised as an adsorbent for developing methodology for the removal of these dyes, which does not easily biodegrades in aqueous medium. The adsorption efficiency of natural sand was tested by using Victoria Blue (VB) as model dye. The adsorpion behaviour as a function of the pH of the aqueous dye solution, the contact time, initial concentration of the dye and the amount of adsorbent was studied. All studies were performed at room temperature (298 K). It was observed that under optimized conditions, 91% of VB can be removed from aqueous media.The adsorption data was fitted well by the Langmuir and Freundlich adsorption isotherm, pseudo-second-order and intraparticle diffusion models were also applied., European Chemical Bulletin, Vol 3, No 8 (2014): European Chemical Bulletin

In the present work, a naturally occurring smectite group clay mineral, Montmorillonite, (Mt) has been explored as a vehicle for delivery of an antidepressant drug Venlafaxine hydrochloride, VF. The effect of pH of the drug solution, time and initial drug concentration on drug loading capacity of Mt has been studied. The adsorption isotherm was fitted by the Langmuir model and follows the pseudo-second-order kinetics. The synthesized Mt-VF complexes were characterized by XRD, FTIR, TGA, DSC etc. VF was found to be intercalated in the Mt layers. The release profile of the VF and Mt-VF complex in simulated gastric and intestinal fluids has been discussed. The release behaviour of VF from Mt-VF complexes appears to be sustained/ extended for a period of 12 h and reaches upto 52% in simulated gastric fluid and is stable in intestinal fluid where as pure VF completely gets released in 5.5 h and 3.5 h in simulated gastric and intestinal fluid respectively Out of all kinetic models used to elucidate the drug release mechanism, the best fitting was observed for first order model. On the basis of present studies it can be stated that the synthesized Mt-VF complexes have the potential for developing in to a sustained release formulation for oral drug delivery of an anti-depressant drug VF. This shows a path which can reduce doses substantially from 4 times in 24h to twice in 24 h., European Chemical Bulletin, Vol 3, No 7 (2014): European Chemical Bulletin

The gelling and metal-chelating properties of alginate were combined to develop an adsorbent for heavy metal removal. Biopolymer beads composed of fly ash and sodium alginate proved to be an effective adsorbent for removal of Zn(II) ions from aqueous solutions. The effect of initial pH (2–10), bead dose (10–80), agitation time (1–24 h), beads composition (0.1g–0.7 g fly ash) and Zn(II) ions initial concentration (5–30 mg L-1) on the adsorption process, as well as to what extent the adsorption data obey Langmuir and Freundlich adsorption isotherms were investigated. The maximum adsorption was found 84.20 % within 8 h and after that reaches equilibrium. The adsorption of Zn(II) ions is quite sensitive to pH of the suspension and shows an optimum uptake value at pH 6.0. Maximum adsorption occurred for 40 beads and in case of composition, beads composed of 0.5 g fly ash has shown good results. It is clear from the experimental results that the pH plays an important role in adsorption of zinc ions. The average size, bulk density and swelling ratio of beads calculated are; 0.12 cm, 0.34 g mL-1 and 28.65 respectively. The synthesized beads were also characterized by FTIR, XRD, SEM, TGA/DTA and other methods., European Chemical Bulletin, Vol 3, No 7 (2014): European Chemical Bulletin

Short half life of Propranolol Hydrochloride (PPN), an antihypertensive drug is a prime requirement to develop a formulation which could sustained the release of PPN in the human body and also eliminate daily multiple dosage of Propranolol. In this study organoclay Pluronic F68 modified Montmorillonite (Mt) has been explored as a sustained release carrier for oral delivery of PPN. The developed organoclay PF68-Mt was compared for adsorption capacity of PPN with pristine Mt. A detailed and systematic study to evaluate the effect of pH, time and initial PPN concentration on drug loading capacity of organoclay PF68-Mt and pristine Mt has been evaluated. The synthesized PF68-Mt-PPN composites were characterized by XRD, FTIR, TGA techniques. XRD studies suggested the intercalation of PPN within the pristine Mt and organoclay PF68 - Mt. In vitro drug release profile of PPN from organoclay PF68-Mt composites is compared with that of Pristine Mt and the pure PPN, in simulated gastric and intestinal fluids. The release profile of loaded PPN in organoclay PF68-Mt shows pH dependent release in simulated gastrointestinal fluid. The release behaviour of PPN from PF68-Mt-PPN composites was appeared to be in more sustained manner than prisine Mt and pure PPN over a period of 24 hours. This study suggests that the modification of Mt with a non ionic tri block co polymer Pluronic F68 provides better controlled on the release of PPN as compared to pristine Mt and pure drug. The obtained PF68-Mt-PPN composites with high drug loading capacity and sustained drug release characteristics supposed to be a better oral drug delivery system, for a highly hydrophilic low molecular weight antihypertensive drug PPN. The PF68-Mt-PPN composites developed have the potential to minimize the drug dosing frequency and hence improving the patient compliance. Thus, proposing a new promising formulation for oral sustained release drug delivery., European Chemical Bulletin, Vol 3, No 6 (2014): European Chemical Bulletin

Coumarins are an important class of organiccompounds having biological activities. In the present work coumarinderivatives have been synthesized under solvent free conditions. A catalystbased on clay and heteropoly acid has been synthesized and found to be apotential catalyst for synthesis of coumarin derivatives., European Chemical Bulletin, Vol 3, No 1 (2014): European Chemical Bulletin

In the present study, a naturally occurring clay mineral, Montmorillonite, (Mt) has been explored as a carrier for an antihypertensive drug, Atenolol. The effect of pH, time and initial drug concentration on drug loading capacity of Mt has been evaluated. The adsorption isotherm was fitted by the Langmuir model and follows the pseudo-second-order kinetics. The synthesized Mt-Atenolol complexes were characterized by XRD, FTIR, TGA, DSC etc. XRD data indicates the intercalation of Atenolol within the Mt layers. The release profile of the Atenolol from Mt-Atenolol complexes is compared with the pure Atenolol, in simulated gastric and intestinal fluids. The release behaviour of Atenolol from MT-Atenolol Complexes appears to be in sustained manner over a period of 24 hours and reaches upto 40% and 27% in simulated gastric and intestinal fluids respectively. As compared to pure Atenolol, extended gastric retention time was observed for Atenolol-Mt complexes indicative of the increased extent of absorption and bioavailability of the drug. Various kinetic models were used to elucidate the drug release mechanism, the best fitting was found for Higuchi and Korsmeyer-Peppas model. The synthesized Atenolol-Mt complexes have the potential for developing in to a sustained release formulation for oral drug delivery. Thus, proposing a promising formulation for oral sustained drug delivery of Atenolol., European Chemical Bulletin, Vol 2, No 11 (2013): European Chemical Bulletin

In this paper, a clay based drug delivery system comprising of [poly (D, L-lactide-co-glycolide)] (PLGA)/montmorillonite (MMT) nanocomposite has been explored for the oral sustained release of diclofenac sodium (DS) using double emulsion solvent evaporation technique. Encapsulation of diclofenac sodium in PLGA matrix and clay matrix was also undertaken to assess the role of clay and PLGA in drug encapsulation and its subsequent release from the respective formulations. A drug encapsulation efficiency of 98% was obtained for the synthesized PLGA/MMT nanocomposite system. The drug was found to be intercalated in the PLGA/MMT nanocomposite as confirmed by the X-Ray diffraction studies. The thermal analysis shows the crystalline nature of the encapsulated drug in the nanocomposite. The particle size of the drug loaded PLGA/MMT nanocomposite was found to be in the range of 10-20 nm as analysed by high resolution transmission electron microscopic technique (HRTEM). The in vitro drug release studies of the drug encapsulated PLGA/MMT nanocomposite under simulated gastric fluid (phosphate buffer saline, PBS 1.2) shows no drug release while a sustained release was seen under simulated intestinal condition (phosphate buffer saline, PBS 7.4) releasing 51% drug in 8 hours., European Chemical Bulletin, Vol 2, No 9 (2013): European Chemical Bulletin