Encapsulation of halloysite with sodium alginate and application in the adsorption of copper from rainwater

As part of the work, experiments were carried out on a laboratory scale to assess the effectiveness of the use of composite capsules based on halloysite and sodium alginate for the adsorption of copper from rainwater. The halloysite was subjected to acid activation prior to the encapsulation process. The characteristics of the capsules obtained were determined by means of SEM surface imaging, nitrogen adsorption by the BET method and pH_PZC measurement by the suspension method. Adsorption was studied using various operational parameters such as adsorbent dose, contact time, pH and concentration of copper ions in the rainwater. A high percentage of copper ions removal was demonstrated, i.e. 72% for halloysite (H), and 83% for activated halloysite (HA) for a dose of 2.0 g/L. Adsorption of Cu (II) was consistent with pseudo-second order kinetics. The adsorbents showed a high adsorption capacity at the level of 11.03 mg/g, determined by the Langmuir isotherm model. This model fit well with the experimental data.