using eggshell in acid orange 2 dye removal from aqueous solution

background and purpose: generated dye wastewater by the textile industry is usually toxic, non-biodegradable and resistant in the environment. eggshell is one of the inexpensive material and for the reason the vesicular structures can be used as a proper adsorbent for pollutants removal. the aim of this study is to investigate the efficiency of eggshell for removal of acid orange 2 dye from aqueous solution. materials and methods: in the experimental study was determined the efficacy of variant variables such as contact time (15, 30, 60, 90 and 120 min), ph (3, 7 and 11), adsorbent dose (10, 25, 50 and 75 g/l), and initial dye concentration (25, 50 and 100 mg/l). the concentration of dye by spectrophotometer ultraviolet/visible in the wavelength 483 nm was examined. results: the results showed that with increasing contact time and adsorbent dose, the dye removal efficiency was increased, but with increasing ph and initial dye concentration the removal efficiency was decreased. the maximum of removal efficiency of acid orange 2 dye got in the optimum ph: 3, contact time: 90 min, adsorbent dose: 50 g/l and initial dye concentration: 25 mg/l. adsorption of acid orange 2 dye (r2 = 0.87) follow the freundlich isotherm. conclusion: eggshells can be used as an inexpensive and effective adsorbent for the removal of acid orange 2 dye.