Zn removal from the aqueous environment using a polydopamine/hydroxyapatite/FeO magnetic composite under ultrasonic waves.

In this study, an easily magnetically recoverable polydopamine (PDA)-modified hydroxyapatite (HAp)/FeO magnetic composite (HAp/FeO/PDA) was suitably synthesized to exploit its adsorption capacity to remove Zn from aqueous solution, and its structural properties were thoroughly examined using different analytical techniques. The effect of multiple parameters like pH, ultrasonic power, ultrasonic time, adsorbent dose, and initial Zn concentration on the adsorption efficiency was assessed using RSM-CCD. According to the acquired results, by increasing the adsorbent quantity, ultrasonic power, ultrasonic time, and pH, the Zn adsorption efficiency increased and the interaction between the variables of ultrasonic power/Zn concentration, pH/Zn concentration, pH/absorbent dose, and ultrasonic time/adsorbent dose has a vital role in the Zn adsorption. The uptake process of Zn onto PDA/HAp/FeO followed Freundlich and pseudo-second order kinetic models. The maximum capacity of Zn adsorption ( ) obtained by PDA/HAp/FeO, HAp/FeO, and HAp was determined as 46.37 mg g, 40.07 mg g, and 37.57 mg g, respectively. Due to its good performance and recoverability (ten times), the HAp/FeO/PDA magnetic composite can be proposed as a good candidate to eliminate Zn ions from a water solution.