Shape-tunable CuO-Nd(OH)3 nanocomposites with excellent adsorption capacity in organic dye removal and regeneration of spent adsorbent to reduce secondary waste

Highlights: • The shape of the CuO-Nd(OH)₃ nanocomposite can be controlled by varying the pH of the medium. • BET surface area is highly dependent on the shape of the nanocomposite. • CuO-Nd(OH)₃ nanocomposite showed excellent adsorption capacity of 394.1 mg g^-1 for brilliant blue G from water at 30 °C. • The adsorption follows Lagergren pseudo first order kinetics and Langmuir isotherm. • The spent adsorbent after adsorption is regenerated to minimize waste generation from the whole process. -- Abstract: Herein, we report for the first time, the synthesis of CuO-Nd(OH)₃ nanocomposites via a co-precipitation method coupled with the hydrothermal aging process. Varying the pH of the reaction medium, the shape of the nanocomposites could be controlled which determines their surface areas. These CuO-Nd(OH)₃ nanocomposites exhibit very high adsorption capacity with successful removal of ∼ 97% of brilliant blue G (BBG) from water in 180 min under ambient condition. The adsorption process primarily follows Lagergren pseudo-first-order kinetics. The Langmuir isotherm model fits well with a very high monolayer adsorption capacity of 394.1 mg g⁻¹ at 30 °C. The mechanistic study supports chemisorption-type adsorption between the dye molecule and the adsorbent. Regeneration of the spent adsorbent makes the whole process cyclic and eco-friendly.