UC Riverside

There is an alarming increase of a variety of new chemicals that are now being discharged into the wastewater system causing increased concern for public health and safety because many are not removed by typical wastewater treatment practices. Titanium Dioxide (TiO₂) is a heterogeneous photocatalytic material that rapidly and completely mineralizing organics without harmful byproducts. TiO₂ is synthesized by various methods, which lack the necessary control of crystal size, phase, and morphological features that yield optimized semiconductor materials. Mineralizing organisms demonstrate how nature can produce elegant structures at room temperature through controlled organic-mineral interactions.

Here, we utilize biologically-inspired scaffolds to template the nucleation and growth of inorganic materials such as TiO₂, which aid in controlling the size and phase of these particles and ultimately, their properties. Nanosized rutile and anatase particles were synthesized under solution conditions at relatively low temperatures and mild pH conditions. The effects of reaction conditions on phase and grain size were investigated and discussed from coordination chemistry and coarsening mechanisms. Photocatalytic characterization of TiO₂ phase mixtures was performed to investigate their synergistic effect. The suspension conditions of these catalytic nanomaterials were modulated to optimize the degradation rate of organic analytes.

Through the addition of an organic scaffold during the synthesis reaction, a mechanically robust (elastic) composite material containing TiO₂ nanoparticles was produced. This composite was subsequently heat-treated to produce a porous, high surface area TiO₂ nanoparticulate membrane. Processing conditions were investigated to characterize the growth and phase transformation of TiO₂, which ultimately impacts photocatalytic performance. These bulk porous TiO₂ structures can be fabricated and tailored to act as stand-alone photocatalytic membranes, eliminating the need for nanoparticle recovery systems, thereby reducing processing costs and increasing amount of viable applications of photocatalytic systems.