Chemical oxidation is essential in treating P(I)/P(III)-bearing wastewater, while conventional oxidation processes suffer from low selectivity and high cost induced by oxidant reagents. Herein, a low-cost catalyst PdNi 10 was developed to rival the noble metal Pd, which had been known as the only catalyst enabling chemical-free oxidation of P(I)/P(III) into P(V) by ambient O 2 . The PdNi 10 fabricated via optimized method even outperformed Pd in catalytic activity at identical dosage (0.10 g L −1 ), achieving efficient conversion of 1.00 mM of P(I) into P(V) (>94% in 30 min) with wide applicable pH range from 3.0 to 9.0. The aerobic oxidation of P(I) and P(III) over PdNi 10 was confirmed via scavenging experiments to be both dominated by non-radical pathways with apparent activation energies of 44.5 and 21.3 kJ mol −1 , respectively. Interestingly, the individual roles of Ni components of PdNi 10 in the catalytic oxidation were found negligible. The H 2 O-methanol binary solvent experiment suggested that H 2 O mediated the catalytic reaction and the interfacial OH groups as a result of H 2 O dissociation served as the main reactive oxidant species for P(I)/P(III) oxidation. Furthermore, synergistic mechanism was proposed for the Ni and Pd sites with favorable roles in the essential reaction steps of dehydrogenation and hydroxylation, respectively. This study is believed to advance the treatment strategy of P(I)/P(III)-rich wastewater and to shed new light on the development of low-cost catalysts enabling chemical-free aerobic oxidation processes under facile condition.
Ming Li,Jun-Yang Tao,Liang-Neng Wang,Jia-Wei Li,Yue-Jin Liu,Ming-Hua Zeng
Modification of commercially available biaryl monophosphine ligands via ruthenium(II)-catalyzed P(III)-directed-catalyzed ortho C–H secondary alkylation is described. The use of highly ring-strained norbornene as a secondary alkylating reagent is the key to this transformation. A series of highly bulky ligands with a norbornyl group were obtained in excellent yields. The modified ligands with secondary alkyl group outperformed common substituted phosphines in the Suzuki–Miyaura cross-coupling reaction at a ppm mole level of Pd catalyst.
Phosphite [P(III)], an emerging eutrophication pollutant, has attracted limited attention in recent years. Owing to the higher solubility and resistance to biotransformation of P(III), oxidation of P(III) to phosphate [P(V)] is considered to be necessary to enhance P(III) removal. Herein, an efficient and regenerable magnetic La 2 (CO 3 ) 3 /CoFe 2 O 4 /biochar composite (LCB) was constructed through a facile one-pot hydrothermal method to treat phosphite-laden wastewater. LCB coupled with peroxymonosulfate (PMS) exhibited satisfactory P(III) removal performance through a one-step process for simultaneous oxidation and adsorption of P(III). The adsorption capacity of LCB/PMS for P(III) (71.94 mg/g) was much higher than that of LCB. LCB/PMS system showed high P(III) removal efficiency of 96.62 %, wide pH ranging from 4.0 to 9.0, and good reusability. It also worked well in the existence of anions and humic acid. The quenching experiments and electron spin resonance tests (ESR) revealed the critical role of SO 4 • - in the P(III) oxidation process. Characterization results demonstrated that electrostatic attraction and ligand exchange were responsible for P(III)/P(V) adsorption. Moreover, LCB/PMS system presented desirable performance in eliminating a series of typical organic and inorganic phosphorus. The LCB/PMS system provides a promising and sustainable technology for the purification of P(III)-contaminated water.
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