Carboxymethyl starch as a polymeric plant based excipient in drug delivery

Polysaccharides extracted and isolated from plant products serve as potential candidates in pharmaceutics mainly drug delivery, owing to its biodegradability, bioavailability and non-toxic character. Hydrogels, three-dimensional hydrophilic polymeric networks, exhibit dramatic changes in their swelling behaviour, network structure, and mechanical strength in response to different stimuli to the body. A wide variety of polysaccharides (chitosan, alginate, cellulose, starch, etc) and their derivatives have been used to synthesize hydrogels that tend to swell in water or biological fluids. Such systems have numerous biomedical applications including: drug delivery, wound dressing, and tissue engineering. However, single-network hydrogels have weak mechanical properties and slow response at swelling. To enhance the mechanical strength and swelling/deswelling response of hydrogels, multicomponent networks as interpenetrating polymer networks have also been reported and recently have gained much importance in research on different biomedical applications. The present review focuses on the application of carboxymethyl starch as a pharmaceutical excipient where the effect of crosslinking modification and the formation of Semi Interpenetrating Polymer Network with montmorillonite clay mineral have been investigated

Removal of cadmium(II) from aqueous solutions by steam-activated sulphurised carbon prepared from sugar-cane bagasse pith: kinetics and equilibrium studies

Removal of cadmium(II) from aqueous solutions was studied using steam activated sulphurised carbon (SA-S-C) prepared from bagasse pith (a sugar-cane industry waste). Batch adsorption experiments were performed as a function of solute concentration, contact time, adsorbent dose, pH, temperature and ionic strength. The maximum removal took place in the pH range of 5.0 to 9.0. The maximum adsorption of 98.8 % (24.70 mg/g) took place by SA-S-C with 8.9 % sulphur content at pH 6.0 from an initial Cd(II) concentration of 50 mg/dm3. The sorption process follows pseudo-second-order kinetics. Kinetic parameters as a function of initial concentration and temperature were determined to predict the adsorption behaviour of Cd(II) onto SA-S-C. Decrease in ionic strength of the solution was found to improve the adsorption capacity of the adsorbent. The equilibrium data could be best fitted by the Langmuir adsorption isotherm equation over the entire concentration range (50 to 1 000 mg/dm3). The effectiveness of the SA-S-C for Cd(II) removal was examined and compared with other adsorbents reported in the literature. At solution pH of 6.0, the maximum adsorption capacity of SA-S-C calculated by the Langmuir isotherm is 149.93 mg/g at 30°C. Acid regeneration was tried for several cycles with a view to recover the sorbed metal ions and also to restore the sorbent to its original state. Keywords: Adsorption dynamics , Langmuir equation, Cd(II) removal, Sulphurised carbon, Desorption (WaterSA: 2003 29(2): 147-156