REMOVAL OF METALS FROM PETROLEUM PRODUCED WATER BY DOLOMITE

在美国，石油和天然气的生产每年产生超过8900亿桶受污染的废水，通常被称为采油废水(PW)。这种PW通常含有高浓度的盐(主要是氯化钠)和广泛的碱土金属、重金属和自然产生的放射性物质。这些污染物包括钙(Ca)、镁(Mg)、钡(BA)、锶(Sr)、砷(As)、镉(Cd)和镭(Ra)。这种高浓度的盐和有毒金属的结合使得PW的处理和再利用非常具有挑战性和成本。该项目的总体目标是探索利用低成本的白云石过滤器来去除高盐度PW中的有毒金属。在有希望的初步结果的基础上，首席调查人员(PI)建议调查控制白云石在一定范围的水相盐度、温度和组成范围内从PW中去除有毒金属离子及其混合物的机制和过程变量。该项目的成功完成将使社会受益，因为它将产生基础知识，以促进低成本白云石过滤技术的开发和实施，以去除PW和其他高盐度废水中的有毒金属。还将通过外联和教育活动为社会带来更多好处，包括指导俄克拉荷马州立大学的两名研究生和密苏里科技大学的一名研究生。在美国，每生产一桶石油，油井和气井大约产生10加仑的水。这些产出水(PW)含有高浓度的盐类和有毒金属，因此必须经过处理才能再利用。然而，由于高昂的处理成本，美国的大部分PW是通过向地下地层深层注入的方式处置的，在那里它可能会污染淡水资源和/或引发地震活动。本项目的目标是研究使用低成本的白云石过滤器去除PW模型中的有毒金属及其混合物，该过滤器使用Ba2+(Ba2+)、Sr2+(2)、As2+(As2+)和Cd(2+)作为模型有毒金属离子。为了推进这一目标，首席调查员(PI)建议实施一项围绕四个目标构建的综合实验和建模研究计划。目的1采用间歇和流动柱实验研究水相盐度、组成和温度对白云石去除有毒金属离子的影响。目的利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线荧光(XRF)和扩展X射线吸收精细结构(EXAFS)等成像和分析手段，评价白云石表面形态和成分的变化对有毒金属离子去除的影响。目标3将使用表面滴定和电动测量相结合的方法来确定有毒金属离子与白云石在不同水相组成、盐度和温度范围内的固有稳定常数。目的4将探索表面络合和反应传输模型的发展和验证，以模拟白云石过滤去除PW中的金属。这项研究的成功完成有可能通过产生新的基础知识和建模工具来促进白云石过滤的设计和实施，作为一种有效和经济的技术来去除高盐度PW中的有毒金属离子。为了实施该项目的教育和外联活动，私人投资机构计划将这项研究的结果纳入俄克拉荷马州立大学和密苏里州科技大学(密苏里州S和密苏里大学)现有的和相关的课程模块。此外，私人投资机构建议利用各自机构的现有计划，从代表性不足的群体中招募研究生/本科生来参与这个项目，包括俄亥俄州立大学的路易斯·斯托克斯少数族裔参与联盟和密苏里州S的夏季工程研究院。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In the United States, every year, the production of oil and gas generates more than 890 billion barrels of contaminated wastewater, commonly referred to as produced water (PW). This PW typically contains high concentrations of salts (predominantly sodium chloride) and a broad range of alkaline earth metals, heavy metals, and naturally occurring radioactive materials. These contaminants include calcium (Ca), magnesium (Mg), barium (Ba), strontium (Sr), arsenic (As), cadmium (Cd), and radium (Ra). This combination of high concentrations of salts and toxic metals makes the treatment and reuse of PW very challenging and costly. The overarching goal of this project is to explore the utilization of low-cost dolomite filters to remove toxic metals from high salinity PW. Building upon the results of promising preliminary results, the Principal Investigators (PIs) propose to investigate the mechanisms and process variables that control the removal of toxic metal ions and their mixtures from PW by dolomite over a range of aqueous phase salinity, temperature, and compositions. The successful completion of this project will benefit society through the generation of fundamental knowledge to advance the development and implementation of low-cost dolomite filtration technology to remove toxic metals from PW and other high-salinity waste streams. Additional benefits to society will be achieved through outreach and educational activities including the mentoring of two graduate students at Oklahoma State University and a graduate student at Missouri University of Science and Technology. Approximately, 10 gallons of water are generated by oil and gas wells for each barrel of oil produced in the United States (US). This produced water (PW) contains high concentrations of salts and toxic metals and therefore must be treated to enable its reuse. However, due to high treatment costs, most of the PW in the US is disposed of via deep injection into subsurface formations where it can potentially contaminate freshwater resources and/or induce seismicity. The goal of this project is to investigate the removal of toxic metals and their mixtures from model PW by lower-cost dolomite filters using barium (Ba), strontium (Sr), arsenic (As), and cadmium (Cd) as model toxic metal ions. To advance this goal, the Principal Investigators (PIs) propose to carry out an integrated experimental and modeling research program structured around four objectives. Objective 1 will investigate the effects of aqueous phase (PW) salinity, composition, and temperature on toxic metal ion removal by dolomite using batch and flow through column experiments. Objective 2 will evaluate the effects of changes in dolomite surface morphology and composition on toxic metal ion removal using a combination of imaging and analytical tools including scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray fluorescence (XRF) spectroscopy, and extended X-ray absorption fine structure (EXAFS) spectroscopy. Objective 3 will determine the intrinsic stability constants of toxic metal ion complexation with dolomite over a range of aqueous phase compositions, salinities, and temperatures using a combination of surface titration and electrokinetic measurements. Objective 4 will explore the development and validation of surface complexation and reactive transport models to simulate the removal of metals from PW by dolomite filtration. The successful completion of this research has the potential for transformative impact through the generation of new fundamental knowledge and modeling tools to advance the design and implementation of dolomite filtrations as an efficient and cost-effective technology to remove toxic metal ions from high salinity PW. To implement the education and outreach activities of the project, the PIs plan to integrate the findings from this research into existing and relevant course modules at both Oklahoma State University (OSU) and Missouri University of Science and Technology (Missouri S&T). In addition, the PIs propose to leverage existing programs at their respective institutions to recruit graduate/undergraduate students from underrepresented groups to work on this project including the Louis Stokes Alliances for Minority Participation at OSU and the Summer Engineering Research Academy at Missouri S&T.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.