Shrimp shell as an efficient bioadsorbent for Acid Blue 25 dye removal from aqueous solution

• P. indicus shell is a cheap, efficient sorbent to remove Acid Blue 25 dye from water.
• Acid Blue 25 dye biosorption kinetics and thermodynamics are studied.
• Acid Blue 25 dye biosorption is feasible, spontaneous and exothermic.
• Biosorption capacity increases by decreasing sorbent particle size and adding salts.

This study focused on kinetics, equilibrium and thermodynamics of Acid Blue 25 (AB25) dye biosorption from aqueous solution using the shell of Penaeus indicus shrimp as a biosorbent. Optimum sorption conditions were identified by varying solution pH, biomass dosage, initial dye concentration, contact time, salinity and ionic strength. Equilibrium data were well fitted by the Temkin, Freundlich and Langmuir isotherm models, while the pseudo-second order model best described kinetics. Thermodynamic data showed that AB25 dye biosorption onto shrimp shell was a feasible, spontaneous and exothermic one. The biosorption capacity increased with decreasing the sorbent particle size and with the addition of salts (NaCl, MgSO4, KNO3 and KH2PO4). The high sorption capacity of P. indicus shell obtained in this study suggests its use as an effective, low-cost biosorbent for the removal of acid dyes from wastewaters.