Applied Study Of Hollow Nano-framework Prussian Blue Analogues And Derivatives In The Degradation Of Organic Pollutants In Water

In order to degrade and treat increasingly complex organic pollutants in water bodies,advanced oxidation of peroxides(SR-AOPs),a new advanced oxidation technology,is an efficient means of treating organic wastewater.Since conventional homogeneous iron-based catalysts are not very efficient at activating peroxides,the development of catalysts that can efficiently activate peroxides is currently a hot topic.In this study,nanocuboids assembled frame-like superstructure Prussian blue analogues,namely Co-Fe PBA NAFSs,were prepared,which successfully overcome the weaknesses of conventional metal organic frameworks(MOFs)materials in terms of their instability in water and can efficiently activate peroxynitrite(PMS)for advanced oxidative degradation of organic pollutants.In addition,cobalt-iron bimetallic oxides(CoFeO-NAFSs)were prepared by calcination of nanocuboids assembled frame-like superstructure Prussian blue analogues to further enhance their catalytic PMS advanced oxidative degradation of organic pollutants while retaining their original morphology.The main research elements and results are as follows:(1)Co-Fe PBA NAFSs with nanocuboids assembled frame-like superstructures were synthesised by a one-pot method and their crystal structures,morphological features and compositions were analysed by a series of characterisations.Co-Fe PBA NAFSs were used in the activation of PMS for the degradation reaction of rhodamine B(RhB)and tetracycline hydrochloride(Tc-HCl),both with a catalyst dosing rate of 0.10 g/L.At a PMS dosing rate of 0.10 g/L,99%degradation was achieved at 35 min for 50 ppm RhB;at a PMS dosing rate of 0.50 g/L,20 ppm Tc-HCl reached 95.8%degradation at 90 min.By comparing similar catalysts from other literature,the Co-Fe PBA NAFSs catalysts offer the advantages of higher catalytic activity,lower consumption of PMS and shorter reaction times.The catalysts were subjected to cyclic repetition experiments for the degradation of contaminants and SEM characterisation of the catalysts after the cyclic repetition experiments.The SEM results showed that the catalysts after the cyclic repetition experiments showed almost no change in morphology from the pre-reaction period and showed excellent stability in water.The radical quenching experiments revealed that the order of radical action in the catalytic degradation reaction was 1O2>SO4·->OH·>O2·-,with the dominant active substance being 102,and a possible mechanism for the activation of the Co-Fe PBA NAFSs catalyst for the degradation of organic pollutants by PMS was postulated.(2)The Co-Fe PBA NAFSs were calcined at 250℃ in an air atmosphere to yield hollow nano-framework structures of cobalt-iron bimetallic oxides CoFeONAFSs,which were analysed by a series of characterisations of their crystal structure,morphological features and compositional composition.CoFeO-NAFSs were used in the activation of PMS for the degradation reactions of RhB and Tc-HCl,both with a catalyst dose of 0.10 g/L.When PMS was dosed at 0.05 g/L,99%degradation of RhB at 50 ppm was achieved at 14 min;when PMS was dosed at 0.30 g/L,respectively,50 ppm Tc-HCl at The degradation rate reached 93%at 90 min.CoFeO-NAFSs have better catalytic properties than both CoFeO-NCs(nanocubes)and Co-Fe PBA NAFSs and are more resistant to acids and bases than Co-Fe PBA NAFSs.By comparing similar catalysts from other literature,the CoFeO-NAFSs catalysts offer the advantages of higher catalytic activity,lower consumption of PMS and shorter reaction times.The data results show good stability and recyclability of the CoFeONAFSs and the recyclability of the CoFeO-NAFSs is also superior to that of the CoFe PBA NAFSs,through the cyclic repetition of the catalysts for the degradation of pollutants and the characterisation of the catalysts after the cyclic repetition experiments.The results of radical quenching experiments and electron paramagnetic resonance spectrometry(EPR)tests revealed that the dominant active substance in the catalytic degradation reaction is 102,and a possible mechanism for the activation of the CoFeO-NAFSs catalyst for the degradation of organic pollutants by PMS was postulated.Based on the experimental results of the activation of PMS by CoFeONAFSs for the catalytic degradation of different types of organic dyes and antibiotics,it is evident that CoFeO-NAFSs can effectively activate PMS for the catalytic degradation of different organic dyes and antibiotics,reflecting the superiority and universality of CoFeO-NAFSs catalysts in catalytic degradation.The possible molecular structures of the intermediate products of NOR catalyzed by CoFeONAFSs were also characterized and analyzed by hybrid quadrupole-TOF mass spectrometry(HQ-MS),which confirmed the oxidation of organic pollutants to small organic molecules and finally mineralized to inorganic small molecules,proving the real effectiveness of the catalytic degradation of organic pollutants by CoFeO-NAFSs activated by PMS.