Removal of crystal violet from aqueous solution using desert date (Balanites aegyptiaca) seed shell

Abstract

The feasibility of utilizing desert date seed shell (DDSS) as an alternative low-cost adsorbent for the removal of hazardous crystal violet (CV) dye from aqueous solution was investigated. The prepared adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy (Cary 630; Agilent Technologies) and scanning electron microscopy (PRO: X: Phenonm World 800-07334). The influence of operational parameters such as contact time, adsorbent dosage, pH, and temperature were studied using batch mode technique. The obtained results showed that 60 min contact time, 0.4g adsorbent dose, solution pH of 8 and 60 oC temperature resulted in maximum CV removal. The equilibrium data fitted very well to Freundlich model (R 2 = 0.9983) and the KF and 1/n values were found to be 31.21 dm3
g ^-1 and 0.828 respectively. The maximum adsorption capacity of DDSS for CV as determined by Langmuir isotherm is 294.12 mg g ^-1
at 303K. Kinetic analysis revealed that the pseudo second order was the best model (R 2 = 0.9999) for the description of CV uptake with the experimental value of qe 20.3575 mg g ^-1 being closer to the calculated value of the qe 20.3651 mg g ^-1 . Thermodynamic studies revealed a negative value for ∆G o (-11.07 kJ mol ^-1 ) and a positive value for ∆H o (33.75 kJ mol ^-1 ) and ∆S o (134.9 J mol ^-1 K^-1  ). These indicated the  spontaneous and endothermic nature of the adsorption process.

Keywords: Adsorption, Desert date seed shell, Crystal violet, Batch  mode, Modeling