Kelp-derived N-doped biochar activated peroxymonosulfate for ofloxacin degradation.

N-doped carbon materials have been proven to be effective catalysts for activating peroxymonosulfate (PMS). Marine algae biomass is rich in nitrogenous substances , which can reduce the cost of N-doping process and can obtain excellent N-doped catalysts cheaply and easily. In this study, kelp biomass was selected to prepare N-doped kelp biochar (KB) materials. The high defect degree, high specific surface area, and participation of graphite N make KB have excellent catalytic degradation ability. The KB degraded 40 mg/L ofloxacin (OFL) close to 100% within 60 min, applied with PMS. Through quenching experiments and electron paramagnetic resonance spectroscopy, the degradation process dominated by non-radical pathways was determined. At the same time, O2·- and 1O2 were closely related, and a significant impact of quenching O2·- on the reaction was observed. The non-radical approach made the system excellent performance over a wide pH range and in the presence of multiple anions. The experiments of reusability confirmed the stability of the material. Its catalytic performance was restored after low-temperature pyrolysis. This research supports the use of endogenous nitrogen in biomass. It provides more options for advanced oxidation process application and marine resource development.

Preparation and Characterization of Macroalgae Biochar Nanomaterials with Highly Efficient Adsorption and Photodegradation Ability.

In this study, carbonized kelp biochar (AKB) modified by KOH impregnation and photocatalytic Bi2MoO6/AKB composite (BKBC) nanomaterials were the first time successfully synthesized for efficient removal of dyes in aqueous solution. BET, XRD, FT-IR, and SEM were employed to characterize as-prepared samples. UV-vis and other test results indicated that the removal efficiency of methylene blue (MB) was 61.39% and 94.12% for BKBC and AKB, respectively, which was up to 13 times and 20 times higher in comparison with pure Bi2MoO6 (PBM). In addition, the equilibrium adsorption capacity of MB could reach up to 324.1 mg/g for AKB. This high dyes adsorption performance could be likely attributed to its high specific surface area (507.177 m²/g) and its abundant presence of various functional groups such as ⁻OH and =C⁻H on AKB. Particularly, the existing of amorphous carbon and transition metal oxides, such as Fe2O3 and Mn5O8, could be beneficial for the photodegradation of MB for AKB. Meanwhile, experimental data indicated that adsorption kinetics complied with the pseudo-second order model well, and all of the tests had satisfactory results in terms of the highly efficient adsorption and photodegradation activity of AKB nanomaterials, which suggested its great potential in wastewater treatment.