Continuous Flow Process for Recovery of Metal Contaminants from Industrial Wastewaters with Magnetic Nanocomposites

摘要

Remediation of metal-containing industrial effluents presents both a technical challenge and an economic opportunity. Many industrial waste streams contain low levels of metal ions requiring treatment prior to discharge. Existing treatment technologies are frustrated by disparate compositions and low metal concentrations. Chemical precipitation is effective; however, it requires excessive reagents and discourages selective recovery. Ion-exchange enables recovery, but requires a batch process with extensive operational and maintenance demands, and is rarely implemented in large-scale applications. A continuous flow process capable of selective recovery would present many advantages over existing technologies.;This research examines and develops a continuous flow process for recovering metals from industrial wastewaters with magnetic nanocomposites. The objective of this project was to prove the concept and elucidate the mechanisms, and to demonstrate potential for industrial application. All aspects of this process were investigated and optimized to the extent possible. Specific experimentation focused on the development of magnetic nanocomposite ion exchange media, magnetic collection technology, metal recovery, reactor and process development, and modeling.;An effective ion exchange media was developed with a magnetically susceptible magnetite core, durable silica shell, and polyallylamine functionalization. Metal ion loading behavior was demonstrated and modeled, with rapid kinetics and long-term regeneration potential. An in-line, water-cooled magnetic collection module was developed with collection efficiencies exceeding 98%. A pilot-scale vertical reactor was designed and modeled under steady-state operation. Experiments showed efficacy with surrogate solutions as well as actual mine affected waters. A viable metal recovery process was demonstrated with an annular tangential-flow electrowinning technology.;The experimental results proved that this novel nanocomposite magnetic ion exchange media are an effective and reusable means of metal ion removal. Paired with the innovative electromagnetic collection module, a continuous flow process is made possible with low energy demand and pressure differential. This process is effective and predictable, and scalable to industrial applications. These collective findings substantiate the viability of a continuous flow process for recovery of metal contaminants from industrial wastewaters with magnetic nanocomposites.