Impregnation of copper-cysteamine nanoclusters containing Cu(I) and Cu(II)-ionic species on pristine and magnetic bentonite for efficient Fenton-like catalysis and higher dye adsorption

Abstract

Copper-cysteamine nanoparticles are known for their capability to produce reactive oxidation species upon light irradiation. During the synthesis of copper-cysteamine nanoparticles, many intermediate species are produced possessing Cu in variable oxidation states and herein we successfully trapped an intermediate species (CC) containing both Cu+1 and Cu+2 on bentonite (B) and magnetic bentonite (BF). The synthesized products (BCC and BFCC) were employed for the Fenton-like degradation of hazardous organic dyes and proved to be highly effective in splitting H2O2 to produce reactive ●OH radicals for carrying out the photocatalytic degradation process. Degradation data fitted with pseudo-first-order kinetics model yielded higher rate constants of 0.049 s−1 and 0.041 s−1 for Congo red (CR) degradation by BCC and BFCC respectively, with retained catalytic efficacy for three repeated cycles. Products were also tested for CR adsorption and adsorption isotherm studies conducted at optimized reaction conditions were best explained by Langmuir isotherm model exhibiting the maximum adsorption capacity of 781 mg/g and 800 mg/g for BCC and BFCC respectively. Adsorption kinetics data fitted best with the pseudo-second-order model while thermodynamics study suggested the exothermicity and spontaneity of the adsorption process. In short, CC deposition on bentonite-based materials produced excellent photocatalysts and adsorbents exhibiting the two-way benefits of our synthesized products.