Date Palm Flower Stalk: A Potential Low-cost Biomass for Efficient Removal of Textile Dyes from Wastewater

Hazardous pollution of water sources is a major impediment to the supply of usable and potable water around the world. Economical, innovative, renewable and environmentally friendly technologies are needed for the treatment of wastewater. Untreated waste materials, like date palm flower stalks (PFS) collected directly from trees, can serve as adsorbents for removing textile dyes. Batch kinetic and equilibrium experiments performed to investigate the effects of various factors, including contact time (0 – 180 min), adsorbent dose (10–50 mg / 25 mL), initial pH (2 – 12), initial concentration of dye (0 – 200 mg/L) and temperature (15 – 60 °C). The equilibrium capability achieved after 90 min of biosorption was 38.522 mg/g. The Freundlich and Langmuir isotherm models were fitted to the experimental data and their goodness of fit for adsorption was compared. Langmuir isotherm (R² ~ 0.998) best described the equilibrium of SRL sorption on PSF. Adsorption was found to be greater under highly basic conditions (pHpzc = 6.3). The thermodynamic parameters such as Gibbs free energy ΔG°, enthalpy change ΔH°, and entropy ΔS° were calculated. Adsorption Gibbs free energy (ΔG°) was calculated to be in the range -8.49 to -8.62 kJ / mol. The values of activation parameters such as enthalpy (ΔH°) and entropy (ΔS°) were also determined as -7.76 kJ / mol and 2.49 J / mol.K, respectively. These findings indicate that palm flower stalk would be suitable adsorbents for textile dyes in wastewater.