| Abstrakt: |
Azo dyes are well known recalcitrant and hazardous pollutants from dyeing industries which are essentially needed to be removed from the industrial effluents before discharged in the environment. Among many dye removal techniques, biosorption has gained attraction due to eco -friendliness and cost effectiveness. Biosorption of pollutant is surface phenomena which is resultant of the physicochemical interactions between biologically originated surfaces and the pollutant molecules. On the other hand, biomass from agro-industrial activities (e.g., rice straw, rice husk, wheat straw etc.) poses significant adversity on the environment, if traditional management practices are adopted. This study integrates the use of biomass for azo dye removal. It focusses on the utilization of rice straw biomass for removal of azo dye in the purview of sustainable environmental management. Biosorption of methylene blue dye (MB) by the use of rice straw and surface modified rice straw was studied. Rice straw powder (RSP) was treated with autoclaved sea water (RSP-ASW) and Sodium dithionite (RSP-SDT) and their characteristics was studied. Proximate analysis suggests the improvement in chemical composition by the treatments. The surface characterization with FTIR, PZC and SEM inferred the effect of modifying agents on RSP. Batch biosorption experiments were conducted to check the effect of operating parameters, viz., solution pH (pH3 -- pH11), temperature (298K-318K), initial dye concentration (50 mg/L-200 mg/L), contact time (0 -- 360 minutes), and adsorbent dosage (0.25 gm -1 gm) on MB removal. The preliminary investigations on sorption equilibrium of MB on pre-treated and untreated rice straw biomass showed the highest congruity with the Langmuir isotherm model, among the four adsorption isotherm models, viz., Freundlich, Langmuir, Temkin and DubininRadushkevich (D-R) isotherm models. The adsorption process follows the pseudo second order kinetics. The MB removal achieved was in the order RSPSDT> RSP-ASW>RSP in all the adsorption experiments conducted. The maximum dye removal efficiency was 181.8 mg of MB / gm of RSP-SDT at neutral pH and room temperature. [ABSTRACT FROM AUTHOR] |
