Tailoring of carbon-encapsulated nickel nanoparticles/biochars for efficient degradation of tetracycline

Yi Guo^1*Rong Wang²

• ¹Yibin Housing and Urban-Rural Development Administration of Sichuan Province, Yibin, China
• ²Yibin Xuzhou District Natural Resources and Planning Bureau of Sichuan Province, Yibin, China

As excellent peroxydisulfate (PDS) activators to degrade antibiotics, metallic nanoparticles (NPs) suffer from continuous ion leakage and declined efficiency. Herein, graphene coated nickel (Ni@G) NPs with 23.9-28.5 nm of Ni core and 7.9-2.1 layers of graphene shell were regulated via laser ablation in ammonia solution. Ni@G-loaded biochars (Ni@G/Bs) with developed porosity (23.8-145.7 m2/g) were prepared via crosslinking Ni@G with biochars derived from the pyrolysis of rice hull at 300oC, 450oC and 600oC. By investigating the effects of catalyst species and dosage, PDS dosage, tetracycline concentration, circumstance temperature and coexisting anions, Ni@G/Bs presented k values of 0.0094-0.0301 min-1 for tetracycline degradation which were 47.0-81.5 fold enhancement than biochars. 7.26-3.61 μg/L of nickel ion leakage for 1st-5th cycles verified the excellent stability of Ni@G/Bs. Paracetamol (72.4%), ciprofloxacin (76.7%) and aureomycin (68.2%) could be degraded, showing a superior versatility of Ni@G/Bs. Free radical degradation pathway involving •OH, •SO4− and •O2-governed the degradation mechanism. While the non-free radical pathway mediated by 1O2 should not be ignored. This study paved a way for adjusting laser-ablated core/shell NPs and provided a new insight for integrating metal NPs and biochars to efficiently degrade antibiotics.