A green strategy for porous biochar fabrication with superior capacity for peroxydisulfate activation to degrade sulfadiazine:the cooperative role of C-sp^(3) and specific surface area

Metal-free porous biochars are popularly utilized as catalysts for peroxydisulfate(PDS)activation.The enhancement effect of PDS activation of porous biochars fabricated by employing both hard template and alkali metal activating agent has not been explored completely.In addition,the role of the inherent carbon defect in PDS activation has not been clearly elucidated.Hence,a series of carbonaceous catalysts were fabricated using a sole template(KCl),a sole activating agent(Na_(2)S_(2)O_(3))or a combination of template and activating agent(KCl/Na_(2)S_(2)O_(3),KCl/KHCO_(3),KCl/NaHCO_(3),and KCl/Na_(2)C_(2)O_(4)),to systematically investigate the effect of specific surface area(SSA)and intrinsic defect of porous biochar on its PDS activation ability.The biochar synthesized by KCl and Na_(2)S_(2)O_(3)(SK-C)exhibited the optimum degradation performance.The SK-C was found to possess an interconnected hollow cage with three-dimensional mesh structure showing the largest surface area,pore volume and C-sp^(3) edge defect content among all the catalysts,which explained its paramount catalytic ability.The SSA and C-sp^(3) content together can determine the catalytic performance in a quantitative relationship.The single electron transfer pathway from SDZ to inner-sphere bound SK-C/PDS*was the protagonist of pollutant oxidation.The degradation intermediates were detected and recognized and their toxicities were evaluated.This study for the first time comprehensively identified the synergistic effect between the SSA and inherent defects on improving the catalytic performance of biochar for PDS activation to removal contaminants.

Aromatic and olefinic C–H alkenylation by catalysis with spirocyclic NHC Ru(Ⅳ) pincer complex

Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.

Endow activated carbon with the ability to activate peroxymonosulfate for the treatment of refractory organics

Herein,we demonstrated that various activated carbons could be endowed with high ability activating peroxymonosulfate(PMS)just through pyrolysis for the degradation of various organic pollutants.The ofloxacin(OFX)was proved to be degraded rather than adsorbed in the advanced oxidation processes.The catalyst showed good stability and could be recovered by simple pyrolysis showing the initial activity.The defects were identified as active sites of the catalyst,andπ-π^(*)shake up was related to the catalyst activity.Mediated electron transfer was verified to be responsible for the degradation of OFX.The inhibition effect of furfuryl alcohol(FFA)on the degradation of contaminant was proved to be insufficient to verify^(1)O_(2).The main OFX degradation intermediates were identified by LC-MS,and possible degradation pathways were proposed.This study provided a simple way for the development of low-cost,metal-free,and high-efficient carbonaceous materials to activate PMS in advanced oxidation processes,and proposed new insights for the exploration of PMS activation mechanism.