Their research focused on (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)Fe2O4 a newly developed ferrite material synthesized using the solution combustion method followed by heat treatment (500-1500 °C). This study marks the first application of these HE spinel ferrites as catalysts in a heterogeneous peroxodisulfate reaction for wastewater treatment. The results revealed that the HE spinel ferrite/PDS system exhibited superior efficiency in removing organic pollutants, such as RhB and tetracycline (TC), compared to the baseline reaction conditions. The degradation process was found to be significantly influenced by both hydroxyl and sulfate radicals generated during the reaction. Notably, this catalyst demonstrated remarkable catalytic activity and excellent stability throughout the study, highlighting its potential as a promising candidate for real-world wastewater treatment applications. The study investigated the electrical properties of these materials, focusing on their dielectric constant and loss tangent. Interestingly, both parameters decreased with increasing frequency but increased with rising temperatures. Importantly, the research achieved low dielectric loss tangent values, making these nano-ferrites promising candidates for applications involving microwave frequencies. A new approach to wastewater treatment utilizes biochar derived from banana peels. The biochar is first created using a molten salt technique. Then, a one-pot hydrothermal process incorporates Mn, Zn, and Fe trimetallic spinel onto the biochar, forming a composite named MZF-BC. This MZF-BC demonstrates exceptional tetracycline adsorption, reaching a maximum capacity of 142.4 mg/g. Researchers believe pore filling, coordination with TC functional groups, and interactions within the biochar structure contribute to this high adsorption.