Removal of trace amount of metal ions using magnetic graphene oxide

硒等微量金属元素广泛分布于硫化物矿物和煤灰中。在采矿和矿物加工过程中，硒可以释放到水和土壤中，并进一步转移到生物体及其生命周期中。硒是一种必需的微量营养素，但在较高浓度下具有不利影响。世界卫生组织已将饮用水中硒的指导值设定为低于0.04 mg/L（40 μ g/L或40 ppb）。从水系统中去除硒和其他微量金属对于减少其对环境的影响和保持自然资源的可持续发展至关重要。硒是类金属，具有从-2到+6的可变价态。水体中存在的硒主要是硒酸根和亚硒酸根的含氧阴离子，它们比元素硒（Se）和硒化物（Se 2-）更具有移动的性。 在这项拟议的研究中，一种新的吸附剂，磁性氧化石墨烯（MGO）复合材料将被合成，以研究与外部磁场的应用相结合的硒物种的去除。提出将磁载体技术与高比表面积MGO结合联合收割机去除水中硒氧阴离子等金属离子。磁分离后，MGO将通过剥离吸附的硒和微量金属而回收和再利用。我们的初步结果表明，MGO具有良好的去除率的Se（IV）和Se（VI）。MGO的大比表面积、大吸附容量和高吸水性使其成为一种有前途的废水吸附剂。

Selenium and other trace metals are widely distributed in sulfide minerals and coal ash. During mining and mineral processing, selenium could be released into water and soils, and further transferred to organisms and their life cycles. Selenium is an essential trace nutrient, but has an adverse effect at higher concentrations. A guideline value of less than 0.04 mg/L (40 microgram/L or 40ppb) selenium in drinking-water has been set by the World Health Organization. The removal of selenium and other trace metals from water systems is crucial to reduce their environmental impact and maintain sustainable development of natural resources. Selenium is metalloid and has variable valence states from -2 to +6. The selenium species present in water are mainly oxyanions of selenate and selenite, which are more mobile than elemental selenium (Se) and selenide (Se2-). In this proposed research, a new kind of adsorbent, magnetic graphene oxide (MGO) composites will be synthesized to investigate the removal of selenium species in conjunction with the application of an external magnetic field. We propose to combine the magnetic carrier technology with the high specific surface area MGO for the removal of selenium oxyanions and other metal ions in from water. After the magnetic separation, MGO will be recycled and reused by stripping off the adsorbed selenium and trace metals. Our preliminary results show that MGO has a good removal rate for both Se (IV) and Se (VI). The large surface area, large adsorption capacity, and high water dispersibility of MGO make it a promising adsorbent for use in wastewater.