Canna indica-chitin-alginate composite beads for the treatment of textile dye effluent containing Rose Bengal dye

Aim: To study the adsorption of Rose Bengal dye used in textile industries by Canna indica-chitin-alginate beads. Methodology: C. indica-chitin-alginate composite beads were prepared using root tubers of Canna indica, chitin from shrimp shells and sodium alginate. Batch adsorption of Rose Bengal dye was carried out with optimized parameters like pH, contact time, adsorbent dosage and dye concentrations. Characterization studies like SEM, FTIR and TGA and reusability of composite beads were also studied. Results: The maximum adsorption of 97.9% was obtained at pH 6, 80 min contact time with the optimized ratio of 1:1:0.05 C. indica-chitin-alginate towards 100 mg l-1 dye concentration. The SEM analysis showed a porous surface morphology whereas FTIR results exhibited the functional groups of Rose Bengal dye and composite beads, proving successful adsorption. Thermogravimetric analysis revealed that the composite beads could withstand a maximum temperature of 300oC. Interpretation: It is inferred from the study that a biosorbent prepared from a commonly available plant and shells of shrimp, which is considered as a waste, can be effectively used in the adsorption of harmful textile dyes from the effluent in an eco-friendly and cost-effective way.

Studies on antioxidant enzymes in Canna indica plant under copper stress.

Bright red-flowered Canna indica L. plants were subjected to grow in nutrient solution supplemented with five different concentrations (0, 5, 10, 30 and 50 µM) of CuCl2 to study antioxidant defense responses of the plant. Accumulation of Cu was dose-dependent and much higher in the roots (108- 191µg g-1 d. wt.) than in the leaves (23.36 - 40.43 µg g-1 d.wt.). Total ascorbate content did not changed in both tissues, but ascorbate redox state decreased (0.570-0.640) in Cu-treated Canna roots. In contrast, both total and reduced glutathione contents increased (387-591.9 nmol g-1 f. wt.) considerably in roots, accompanied with enhanced activities of dehydroascorbate reductase (153.3-160 nmol mg-1 protein) and glutathione reductase (67-87.5 nmol mg-1 protein). No significant change, however, was observed for monodehydroascorbate reductase activity in both tissues of the treated plant. The efficient scavenging of hydrogen peroxide was performed by normal (control level) activities of both ascorbate peroxidase and catalase in leaf and increased activity of only catalase in root, preventing its accumulation at toxic concentrations (despite high superoxide dismutase activity) and subsequent damage of membrane lipids by peroxidation. Together, these ensured normal dry weight of leaves and roots, indicating tolerance of Canna indica plant to Cu-induced oxidative stress.