Investigation of Antimony in Natural Water and Leaching from Polyethylene Terephthalate (PET) Bottled Water

Abstract -Antimony (Sb) is one of the trace hazardous compounds in drinking water. Recent studies demonstrated that polyethylene terephthalate (PET) bottles can release antimony into water. It is also found on natural environment such as groundwater and crustal rocks. The natural content of Sb in northern Gyeonggi province in South Korea was very low range from 0.02~0.32 μg/L. The source water and tap water for 15 water supply plants from river or reservoir showed 0.13 μg/L on average. The groundwater concentration from 50 mineral springs indicated significantly low at 0.02 μg/L. The concentration of antimony was investigated in 47 bottled water brands on market. The average of Sb in bottled water brands was 0.57 μg/L. The detection rate was 100% in these products. Otherwise, raw water for bottled water contained 0.32 μg/L of antimony and detection rate was 90.7%. As a results of leaching experiment, antimony content in PET bottled water was increased from 1.04 to 9.84 μg/L under 60℃ after 12weeks. In case, the bottled water was stored in over 35℃, antimony leached into water. UV-ray irradiation to bottled water not induced increasing antimony release into water following 14days

Designing Proton Conductivity in a Metal-Organic Framework from a Molecular Scale

Two design strategies were investigated to enhance proton conductivity of a proton conducting MOF named β-PCMOF2. First design strategy was isomorphous ligand replacement where an entire C3-symmetric trisulfonate ligand was substituted with a C3-symmetric tris(hydrogen phosphonate) ligand to yield PCMOF2½, which had its proton conductivity raised 1.5 orders of magnitude, to 2.1 × 10-2 S cm-1 at 85 °C and 90% relative humidity compared to the parent material, while maintaining the parent MOF structure. To further enhance the proton conductivity of PCMOF2½, isomorphous ligand replacement was paired with heterocycle doping. Seven new PCMOFs were synthesized and investigated. One resulting material, PCMOF2½(Pyrazole), had its proton conductivity raised 1.9 orders of magnitude compared to the parent material, to 1.1 × 10-1 S cm-1 at 85 °C and 90% relative humidity, while maintaining the parent MOF structure. In addition, the exact mechanism of isomorphous ligand replacement synthesis was elucidated to be a thermodynamically driven solid state reaction

Enhancing Proton Conduction in a Metal–Organic Framework by Isomorphous Ligand Replacement

Using the concept of isomorphous replacement applied to entire ligands, a <i>C</i>₃-symmetric trisulfonate ligand was substituted with a <i>C</i>₃-symmetric tris­(hydrogen phosphonate) ligand in a proton conducting metal–organic framework (MOF). The resulting material, PCMOF2¹/₂, has its proton conduction raised 1.5 orders of magnitude compared to the parent material, to 2.1 × 10^–2 S cm^–1 at 90% relative humidity and 85 °C, while maintaining the parent MOF structure

Achieving Superprotonic Conduction in Metal–Organic Frameworks through Iterative Design Advances

Two complementary design strategies, isomorphous ligand replacement and heterocycle doping, have been applied to iteratively enhance the proton conductivity of a metal–organic framework, β-PCMOF2. The resulting materials, PCMOF2¹/₂(Pz) and PCMOF2¹/₂(Tz) (Pz = 1<i>H</i>-pyrazole, Tz = 1<i>H</i>-1,2,4-triazole), have their proton conduction raised almost 2 orders of magnitude compared to β-PCMOF2. The bulk conductivities of these materials are over 10^–1 S cm^–1 at 85 °C and 90% relative humidity (RH), while maintaining the parent MOF structure. A solid state synthetic route for doping 1-D channels is also presented