Adsorption of dyes from aqeous solutions by using activated rosehip (Rosacanina) seeds

In this study, rosehip seeds, which are abundant in our region, were chosen as natural adsorbent. Usability of rosehip seeds activated with sulfuric acid, phosphoric acid and mix of both acids at the same volume proportion was researched. Methylene blue was choosed as cationic dye. Changes of surface properties of activated and unactivated rosehip seeds were examined by SEM, BET, FTIR, Boehm titration, pHpzc and elemental analysis. Batch adsorption method was applied. Adsorption capacity of methylene blue was evaluated in terms of time, pH, initial solution concentration, adsorbent amount and temperature. The adsorption mechanism was tried to explaine by using Langmuir, Freundlich and Dubinin- Raduschevich isotherm models and Psedeu first-order, Psedeu second-order, intraparticle diffusion kinetic models. Thermodynamic studies were done and reusability of activated adsorbents was investigated. According to the characterization results, activation changed the surface properties. Significant increases about adsorption capacity were observed as a result of activation. Adsorption capacities for RS, SRS and MRS were calculated as 39,53 mg/g-181,82 mg/g and 185,19 mg/g respectively. pH changes didn't change the adsorption capacities. While temperature increase decrease the adsorption capacity of RS, it undouptedly increase the adsorption capacity of SRS and MRS. Mechanism of MB adsorption onto rosehip seeds was fit to Langmuir isotherm and pseudo- second order kinetic model. At reusability studies, adsorption capacity percentages decrease from 98% to 95% and from 95% to 94% for SRS and MRS respectively. These results show that activated rosehip seeds can be used at least five times for methylene blue adsorption Key Words : Methylene blue, Adsorption, Active Carbon, Rosehip Seeds