Zinc chloride activated carbon derived from date pits for efficient biosorption of brilliant green: adsorption characteristics and mechanism study

Abstract

Abstract It is critical to remove dyes from wastewater as they cause harm to human and aquatic life due to their carcinogenic, toxic, and mutagenic effects. Here, low-cost activated carbons (CPs) were produced from the date (Phoenix dactylifera L.) pits. The prepared CPs were chemically activated utilizing zinc chloride to obtain activated carbons from date pits (ZCPs). The physicochemical properties, chemical composition, and morphology of ZCPs material and the active surface functional groups involved in adsorption were identified using N2 adsorption–desorption isotherm, scanning electron microscopy, point of zero charges (pHPZC), and Fourier transforms spectroscopy. The ZCPs biocomposite was applied for the Brilliant green (BG) removal from aqueous solutions, where the efficiency was assessed as functions of pH value, foreign ions, the initial dye concentration, dose of adsorbent, adsorption time, and temperature. The outcomes showed that the prepared ZCPs biocomposite exhibited high uptake of BG with a qe of 247.752 mg/g. The isotherm and kinetic studies show that the adsorption process of BG dye onto ZCPs biocomposite followed Langmuir, and pseudo-second-order models, respectively. From the estimated thermodynamic functions, it was found that the nature of the BG dye adsorption process onto the prepared ZCPs adsorbent was endothermic and spontaneous. With a relative standard deviation of less than 3%, the prepared ZCPs were successfully applied for the removal of BG from real water samples with a recovery of more than 90%. The plausible mechanism of BG adsorption onto the prepared ZCPs can be assigned to various interactions, such as pore–filling, electrostatic attraction, H-bonding, and π–π stacking.

Keywords

• Date (Phoenix dactylifera L.) pits
• Activated carbon
• Brilliant green
• Adsorption
• Isotherms