In order to improve the recovery of tungsten ores containing tin minerals,anisic hydroxamic acid(p-methoxy benzohydroxanic acid,PMOB)was synthesized and introduced as novel collector in the flotation of scheelite,wolf...In order to improve the recovery of tungsten ores containing tin minerals,anisic hydroxamic acid(p-methoxy benzohydroxanic acid,PMOB)was synthesized and introduced as novel collector in the flotation of scheelite,wolframite and cassiterite.The flotation performance and adsorption mechanism were investigated by micro/batch flotation,zeta potential measurements and density functional theory(DFT).The micro flotation results showed that the recoveries of scheelite,wolframite and cassiterite using PMOB as collector are 97.45%,95.77% and 90.08%,respectively,and the corresponding recoveries are 91.00%,84.30% and 84.67% for benzohydroxamic acid(BHA).The batch flotation results revealed that the collector dosage could be reduced by about 45% for PMOB compared with BHA,in the case of similar flotation indicators.Zeta potential measurements indicated that PMOB could be adsorbed on the mineral surfaces by chemisorption.Moreover,density functional theory(DFT)calculation results showed that the substituent group—OCH_(3)endues PMOB stronger electron donation ability and hydrophobicity compared with benzohydroxamic acid(BHA),pmethyl benzohydroxamic acid(PMB)and p-hydroxyl benzohydroxamic acid(PHB).展开更多
Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled ...Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).展开更多
基金Projects(2020GDASYL-20200302009,2020GDASYL-20200302004,2019GDASYL-0501007)supported by Guandong Academy of Sciences,ChinaProject(2020YFC1909202)supported by Ministry of Science and Technology of China。
文摘In order to improve the recovery of tungsten ores containing tin minerals,anisic hydroxamic acid(p-methoxy benzohydroxanic acid,PMOB)was synthesized and introduced as novel collector in the flotation of scheelite,wolframite and cassiterite.The flotation performance and adsorption mechanism were investigated by micro/batch flotation,zeta potential measurements and density functional theory(DFT).The micro flotation results showed that the recoveries of scheelite,wolframite and cassiterite using PMOB as collector are 97.45%,95.77% and 90.08%,respectively,and the corresponding recoveries are 91.00%,84.30% and 84.67% for benzohydroxamic acid(BHA).The batch flotation results revealed that the collector dosage could be reduced by about 45% for PMOB compared with BHA,in the case of similar flotation indicators.Zeta potential measurements indicated that PMOB could be adsorbed on the mineral surfaces by chemisorption.Moreover,density functional theory(DFT)calculation results showed that the substituent group—OCH_(3)endues PMOB stronger electron donation ability and hydrophobicity compared with benzohydroxamic acid(BHA),pmethyl benzohydroxamic acid(PMB)and p-hydroxyl benzohydroxamic acid(PHB).
基金support under the National Basic Research Program of China (2009CB421605)National Key Water Program(2009ZX07207-002-03)National Natural Science Foundation of China (20977096)
文摘Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).
