Green synthesis of low-toxicity graphene-fulvic acid with an open band gap enhances demethylation of methylmercury.
The demethylation of methylmercury has received substantial attention. Here, a novel chemical method for the demethylation of methylmercury is proposed. The low-toxicity graphene-fulvic acid (FA, a ubiquitous material in the environment) was synthesized without the use of a chemical reagent. The hybridized graphene-FA presented an indirect open band gap of 2.25-2.87 eV as well as adequate aqueous dispersion. More importantly, the hybridized graphene-FA exhibited 6- and 10-fold higher photocatalytic efficiencies for the demethylation of methylmercury than FA and free FA with graphene, respectively. This result implies that immobilized, rather than free, FA accelerated the catalysis. Furthermore, inorganic mercuric ion, elemental mercury, and mercuric oxide were identified as the primary demethylation products. For free FA with graphene, graphene quenches the excited-state FA, inhibiting the demethylation by electron transfer. In contrast, the graphene of the self-assembled graphene-FA serves as an electron reservoir, causing electron-hole pair separation. Graphene-FA showed a negligible toxicity toward microalgae compared to graphene. The above results reveal that the green synthesis of graphene and organic molecules is a convenient strategy for obtaining effective cocatalysts.
Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.
Xiangang
X
Hu
Li
L
Mu
Kaicheng
K
Lu
Jia
J
Kang
Qixing
Q
Zhou
D001578:Benzopyrans / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D006108:Graphite / Q000138:chemical synthesis / Q000737:chemistry*; D006801:Humans; D008027:Light; D008628:Mercury / Q000737:chemistry; D017669:Mercury Compounds / Q000737:chemistry; D008767:Methylmercury Compounds / Q000737:chemistry*; D058086:Microalgae; D010087:Oxides / Q000737:chemistry; D014867:Water / Q000737:chemistry
D001578:Benzopyrans; D017669:Mercury Compounds; D008767:Methylmercury Compounds; D010087:Oxides; D014867:Water; D006108:Graphite; D008628:Mercury; C019468:mercuric oxide; C004925:methylmercuric chloride; C005023:fulvic acid