Excellence in Research: A Novel High Throughput Forward Osmosis Membrane for Produced Water Treatment

页岩气和石油生产的水力压裂作业消耗大量淡水，最终产生回流水和采出水作为副产品。这些水中的大部分是通过深井注入来处理的，如果处理不当，可能会造成环境危害。理想情况下，产出的水将被处理并排放到环境中。由于采出水中有机污染物和各种盐类的含量很高，因此缺乏有效和成熟的技术来进行这种应用。反渗透对于处理采出水是无效的，因为高矿化度产生的渗透压排斥反渗透所用的水力。正向渗透是一种自然渗透过程，是一种适用于处理采出水的新兴技术。正渗透膜在分离废水中的有机污染物和盐类以及处理高矿化度的采出水方面表现出了良好的性能。然而，要将正向渗透技术应用于工业规模的采出水处理，必须解决一些技术挑战，包括：(1)商业上可用的正向渗透膜通量相对较低，(2)正向渗透过程中有机物沉积引起的膜污染，以及(3)前向渗透过程中以氨-二氧化碳为吸水溶质时膜进水侧的氨损失。该项目将开发一种独特的双皮肤正向渗透膜，旨在克服这些挑战。计算模型将被用来描述改善通量和减轻污垢的机理。研究和教育将通过教育活动和本科生和研究生的培训相结合。这些活动将使学生通过服务学习教学成为社区参与的学者和未来的政策制定者。这项研究的目标是使在工业层面上有效地处理页岩油气产出水成为可能。为了实现这一目标，该项目将研究一种新的高通量正向渗透膜设计，该膜设计优化用于处理高矿化度采油废水。正向渗透膜将由中间纳米纤维支撑层和支撑层两侧的双层超薄皮肤组成。支撑层将是一种含有聚醚酰亚胺和氧化石墨烯的多孔纳米纤维纺织品。为了减少膜污染和防止进水产出水侧的氨损失，膜皮肤上将涂上高度亲水的两性聚合物。将膜的合成、表征和性能评价与分子动力学模拟相结合，制备并优化了一种用于正向渗透工艺处理采出水的膜。开发的用于处理采出水的膜的性能和稳定性将进行长期检验，并将通过生命周期评估来评估新的采出水处理工艺的环境和经济影响。该奖项反映了NSF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。

Hydraulic fracturing operations for shale gas and oil production consume high volumes of fresh water eventually generating flowback water and produced water as byproducts. Much of this water is disposed of through deep-well injection which, if handled improperly, can cause environmental hazards. Ideally, produced water would instead be treated and discharged to the environment. Due to high levels of organic contaminants and various salts present in produced water, there is a lack of efficient and mature technologies for this application. Reverse osmosis is ineffective for treating produced water because the osmotic pressure caused by the high salinity repels the hydraulic pressure used in reverse osmosis. Forward osmosis is an emerging technology that is suitable for treating produced water since it is a naturally osmotic process. Forward osmosis membranes have shown promising performance for separating organic pollutants and salt from some wastewater and for treating produced water at high salinity. However, to apply forward osmosis technologies to produced water treatment at the industrial scale, there are technical challenges that must be addressed, including: (1) relatively low flux of commercially available forward osmosis membranes, (2) membrane fouling caused by deposition of organic matter during forward osmosis, and (3) ammonia loss from the water feeding side of the membrane when ammonia-carbon dioxide is used as draw solute in the forward osmosis process. The project will develop a unique dual-skinned forward osmosis membrane designed to overcome these challenges. Computational modeling will be applied to describe the mechanisms by which flux is improved and fouling is mitigated. Research and education will be integrated through educational activities and training of undergraduate and graduate students. These activities will prepare students to become community-engaged scholars as well as future policymakers through a service-learning pedagogy.The goal of this research is to make it possible to efficiently treat shale oil and gas produced water at the industrial level. Toward this goal, the project will investigate a novel high throughput forward osmosis membrane design that is optimized for treating high-salinity produced water. The forward osmosis membrane will consist of an intermediate nanofibrous support layer and double ultrathin skins on both sides of the support layer. The support layer will be a porous nanofiber textile containing polyetherimide and graphene oxide. To reduce membrane fouling and to repel ammonia loss from the feeding produced water side, the membrane skins will be coated with zwitterionic polymers, which are highly hydrophilic. Membrane synthesis, characterization, and performance evaluation is integrated with molecular dynamics simulation to fabricate and optimize a membrane for produced water treatment using the forward osmosis process. The performance and stability of the developed membrane for treating produced water will be examined over the long-term, and the environmental and economic impacts of the new produced water treatment process will be evaluated through a life cycle assessment.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.