SBIR Phase I: Carbon Nanotube Enhanced Membrane Distillation for Sea and Brackish Water Desalination, and the Treatment of Saline Waste Water

这个小型企业创新研究第一阶段项目的更广泛的影响/商业潜力是，从海洋和微咸水中产生廉价的清洁水的可能性。随着世界人口的迅速增长，可移动水将成为本世纪最重要的技术挑战之一。有没有唯一的？一刀切？海水淡化的方法。在选择要实施的海水淡化技术时，盐浓度、特定离子的存在、能源成本、前处理要求和资本投资等许多因素都是重要的考虑因素。本文提出的碳纳米管强化膜蒸馏是一种温度相对较低的过程，可以利用工业废热和太阳能加热进行海水淡化。小型热水器，如家庭使用的天然气加热器，可以用来生产高质量的饮用水以及家庭消费所需的水。这项技术的另一个主要应用是石油和天然气钻探。水力压裂或水力压裂是一个耗水量大的过程。一口典型的压裂井在其生命周期中消耗数百万加仑的水，并产生高度含盐的产出水。由于其能够处理高盐浓度，建议的方法是处理这些废物的可行替代方案。该项目的技术目标是利用碳纳米管(CNTs)创造突破性的膜性能，用于通过膜蒸馏(MD)进行海水淡化。在MD中，疏水多孔膜将热盐水进料和冷渗透流分开。当加热的盐水通过膜并部分转化为水蒸气时。膜的疏水性阻止了水溶液进入毛孔。然而，脱离氢键后，水蒸气通过并冷凝在膜的渗透侧。新型膜被称为碳纳米管固定膜(CNIM)，通过将碳纳米管固定在膜孔中，它们将作为分子转运体和吸附剂，从而为水蒸气的传输提供额外的途径。CNIM的另一个主要优点是，它比传统膜更不容易受到污染。该提案的主要创新包括使碳纳米管功能化，以最大限度地提高水蒸气传输，同时最大限度地减少污垢。其他目标包括研究一些具有重要商业意义的水样的污垢行为，如海水、发电厂废水和产出水。最后，将开发一个工艺优化工具来优化CNIM-MD设计。

The broader impact/commercial potential of this small business Innovative Research Phase 1 project is the possibility of inexpensive clean water generation from sea and brackish water. With rapidly increasing world population, portable water will be one of the most important technological challenges of this century. There is no unique ?one size fits all? approach to desalination. Many factors such as salt concentration, the presence of specific ions, energy cost, pretreatment requirements and capital investments are important considerations in selecting the desalination technology to be implemented. The carbon nanotube enhanced membrane distillation proposed here is a relatively low temperature process where industrial waste heat and solar heating can be used for desalination. Small water heaters such as the natural gas heaters used in homes can be used to generate high quality drinking water along with what is needed for domestic consumption. Another major application of this technology is in oil and gas drilling. Hydraulic fracturing or fracking is a water-intensive process. A typical frack well uses several million gallons of water over its lifetime and generates a highly saline ?produced water?. With its ability to handle high salt concentrations, the proposed approach is a viable alternative for treating this waste. The technical objectives in this project are to utilize carbon nanotubes (CNTs) to create breakthrough membrane properties for desalination via membrane distillation (MD). In MD, a hydrophobic porous membrane separates a hot salt water feed and a cold permeate stream. As the heated brine passes on the membrane and is partially transformed to water vapor. The hydrophobicity of the membrane prevents the aqueous solution from entering the pores. However, freed from hydrogen bonding the water vapor passes through and is condensed on the permeate side of the membrane. The novel membranes referred to as carbon nanotube immobilized membranes (CNIM) will be developed by immobilizing CNTs into membrane pores where they will serve as molecular transporters and sorbents, thus providing additional pathways for water vapor transport. The other major advantage of CNIM is that it is less prone to fouling than conventional membranes. Key innovations of the proposal include the functionalization of CNTs for maximization of water vapor transport while minimizing fouling. Additional objectives include the study of fouling behavior of some commercially important water samples such as sea water, power plant effluents and produced water. Finally, a process optimization tool will be developed to optimize CNIM-MD design.