Conductive Spacers to Limit RO Membrane Scale Formation

采矿开采会产生大量废水，往往含盐量很高。这种卤水在排放到环境中之前必须经过处理。海水分离的首选技术是反渗透(RO)膜。然而，在高盐度的采矿废水条件下，反渗透膜很快就会被污染。令人担忧的采矿废水含有高浓度的钙和过量的硫酸盐。在此条件下，膜表面形成由致密而尖锐的矿物沉淀物组成的硫酸钙(石膏)垢。这些结垢层阻碍了跨膜水的流动，降低了膜离子的选择性，并可能破坏膜表面。已有研究表明，电场可以破坏矿物鳞片的形成。例如，正的外加电位可以防止钙离子沉积在膜表面，从而限制石膏的形成。在初步研究中，导电薄膜显示出其限制石膏垢形成的能力。然而，导电膜只是在实验室规模上制造出来的，离商业开发还很远。一种更简单的解决方案是用可以施加电压的导电材料取代膜组件中使用的聚合物间隔物。我们的研究将研究在导电间隔物中应用电势作为一种减少或限制矿垢形成的方法。我们将研究在+0.5V到3.0V之间不同的施加电压以及不同的导电金属间隔材料(铝镁、不锈钢和铜)和金属间隔规的影响。

Mining extraction produces large quantities of wastewater, oftentimes with high salt concentrations. This brine must be treated before disposal into the environment. The technology of choice for salt-water separations is reverse osmosis (RO) membranes. However, RO membranes foul quickly under the high salinity conditions of mining wastewaters. The mining wastewaters of concern have high concentrations of calcium with excess sulfate. Under these conditions, a calcium sulfate (gypsum) scale composed of dense and sharp mineral precipitates form on the membrane surface. These scaling layers block trans-membrane water flow, reduce membrane ion selectivity, and can damage membrane surfaces. Electric fields have been shown to disrupt the formation of mineral scale. Positive applied electric potentials, for example, can prevent the deposition of Calcium ions on the membrane surface, thereby limiting the formation of gypsum. In preliminary research, electrically conductive membranes have shown promise for their ability to limit the formation of gypsum scale. Electrically conductive membranes, however, have only been fabricated at the lab scale and are far from commercial development. A simpler solution is to replace the polymeric spacers used in membrane modules with electrically conductive materials to which potentials can be applied. Our research will investigate the application of electric potentials to electrically conductive spacers as a means to reduce or limit mineral scale formation. We will investigate the impact of different applied potentials ranging between +0.5 V and 3.0 V, as well as different electrically conductive metal spacer materials (Al-Mg, stainless steel, and Cu) and metal spacer gauges.