Cyclic biosorption and desorption of acid red 27 onto eichhornia crassipes leaves

Eichhornia crassipes leaves (LEC) have been shown to be a highly effective biosorbent for the toxic dye Acid Red 27 (AR27). For continuous application, LEC biosorbent must be regenerated with a suitable desorption agent. The recovery of bound AR27 and the subsequent reuse of LEC were investigated in the present work over seven AR27 biosorption-desorption cycles. Desorption studies showed that the LEC-biosorbed dye could be effectively desorbed (100% efficiency) using dilute NaHCO₃ solution (0.025 M). Moreover, the biosorbent could be used effectively for at least seven biosorption-desorption cycles without any apparent physical change or damage and with undiminished AR27 biosorption capacity. The AR27 biosorption kinetics was well described by a pseudo-second-order model, whereas a pseudo-first-order model best described the AR27 desorption kinetics. Thus, LEC exhibits remarkable potential for application in detoxification of AR27-contaminated aqueous solutions.