Microwave‐Assisted Hydrothermal Synthesis of CuS Nanostructures for Rapid Methylene Blue Adsorption From Aqueous Solution

ABSTRACT Copper sulfide (CuS) nanostructures were synthesized via a microwave‐assisted hydrothermal method and evaluated for methylene blue (MB) removal from aqueous solutions. Compared to conventional wide‐bandgap photocatalysts, CuS offers a narrow band gap, p‐type semiconducting behavior, and strong surface–dye interactions, making it particularly attractive for rapid water treatment processes. The material crystallized in the covellite phase, exhibiting mixed nanoflower, nanoplate, and nanospherical morphologies with a surface area of 2.8 m 2 ·g −1 and a band gap of 1.25 eV. Adsorption experiments revealed ultrafast dye uptake, reaching equilibrium within 30 min. The process followed the Langmuir isotherm with a maximum adsorption capacity of 1.4 mg·g −1 and a high affinity constant (K L = 2.4 × 10 5 L·mg −1 ). Kinetic analysis indicated pseudo‐second‐order behavior, confirming chemisorption as the rate‐limiting step. Despite the low surface area, CuS displayed remarkable adsorption speed and affinity, highlighting its potential as a rapid, low‐cost, and scalable adsorbent for wastewater purification.