Modification of lignocellulosic biomass as agricultural waste for the biosorption of basic dye from aqueous solution

In this work the efficiency of applying raw or modified date stones by sodium hydroxide as biosorbents for the removal of methylene blue (mb) from water solutions was examined. the date stones (ds) and naoh-modified date stones were characterized with ftir analysis. effects of various parameters like biosorbent dose,initial ph,contact time,temperature,initial dye concentration and particle size on rate of biosorption have been studied. also optimum values of these parameters have been reported. the isotherms studies carried out are reported and it was observed that mb biosorption follows the langmuir isotherm. kinetics data were evaluated by pseudo-first-order,pseudo-second-order and intraparticle diffusion models. the results showed that the biosorption processes of methylene blue on ds and nmds followed well pseudo-second-order kinetics. the calculated thermodynamics parameters,namely,δg,δh and δs showed that the biosorption of methylene blue on raw biomass and modified was spontaneous,endothermic and increased randomness in the solid/solution interface. the monolayer biosorption capacities of methylene blue were found to be 76.54 mg/g for ds and 130.54 mg/g for nmds,respectively at 323 k. the set of the results obtained indicated that ds and nmds could be an alternative for more costly adsorbents used for dye removal.