Nanocatalytic reductive removal of Congo-red dye using boron-loaded cobalt oxide nanocomposites from aqueous solutions

Abstract

Incorporation of non-metal/metalloid/metal dopants into the crystal lattice of cobalt oxide nanoparticles provides a promising approach to design novel nanocatalysts with enhanced catalytic activity for dye removal. Herein, boron-loading cobalt oxide nanocomposites were synthesized via a simple co-precipitation technique for the catalytic removal of Congo red azo dye. The boron-loading cobalt oxide (0.3 M B@Co 3 O 4 ) nanocomposites exhibited approximately 4.2-fold increase in specific surface area (548.13 m 2 g −1 ), reduced band gap energy, and smaller crystallite size than pristine cobalt oxide nanoparticles. Therefore, boron-loaded Co 3 O 4 NPs showed a higher Congo red dye removal efficiency of 98.61 %, an increase of about 1.16 times compared to the pristine Co 3 O 4 NPs (84.85 %) in the preliminary experiment: 5 mg of catalyst, 50 mL of dye solution (50 mg/L), 1 mL of NaBH 4 (0.25 mg/L), and stirring at 400 rpm for 40 min. In addition, kinetic analysis confirmed that the boron-loaded Co 3 O 4 NPs followed pseudo-first-order kinetics, achieving 99.91 % CR dye degradation in 6 min with an apparent rate constant, k, greater than 0.98 min −1 . It is noteworthy that the catalyst maintained a removal efficiency of over 98 % after ten reuse cycles, highlighting its excellent stability and reusability. Therefore, the boron-containing cobalt oxide nanomaterial is a promising nanocatalyst for the catalytic degradation of azo dyes. • B-doped Co 3 O 4 NPs have been well synthesized via a co-precipitation approach. • The catalyst optical, surface, thermal, crystallinity and morphological properties were studied. • B-doping to Co 3 O 4 NPs crystal lattice changes the catalytic removal efficiency of CR dye. • B-doped Co 3 O 4 NPs are a promising nanocatalyst for the catalytic degradation of dyes. • B-doped Co 3 O 4 NPs are stable catalyst and reused for several cycles.