Photocatalytic activity of micron-scale brass on emerging pollutant degradation in water: mechanism elucidation and removal efficacy assessment.

Alloys or smelted metal mixtures have served as cornerstones of human civilization. The advent of smelted copper and tin, i.e. , bronze, in the 4 th millennium B.C. in Mesopotamia has pioneered the preparation of other metal composites, such as brass ( i.e. , mixture of copper and zinc), since the bronze age. The contemporary use of these alloys has expanded beyond using their physical strength. The catalytic chemistry of micron-scale brass or copper-zinc alloy can be utilized to effectively degrade emerging contaminants (ECs) in water, which are presenting significant risks to human health and wildlife. Here, we examine the photocatalytic activity of a commercially available micro-copper-zinc alloy (KDF® 55, MicroCuZn), made with earth abundant metals, for oxidative removal of two ECs. The micron-scale brass is independently characterized for its morphology, which confirms that it has the β-brass phase and that its plasmonic response is around 475 nm. Estriol (E3), a well-known EC, is removed from water with ultraviolet (UV) radiation catalyzed by MicroCuZn and H 2 O 2 -MicroCuZn combinations. The synergy between H 2 O 2 , UV, and MicroCuZn enhances hydroxyl radical (˙OH) generation and exhibit a strong pseudo-first-order kinetic degradation of E3 with a decay constant of 1.853 × 10 -3 min -1 ( r 2 = 0.999). Generation of ˙OH is monitored with N , N -dimethyl-4-nitrosoaniline ( p NDA) and terephthalic acid (TA), which are effective ˙OH scavengers. X-ray photoelectron spectroscopy analysis has confirmed ZnO/CuO-Cu 2 O film formation after UV irradiation. The second EC studied here is Δ9-tetrahydrocannabinol or THC, a psychotropic compound commonly consumed through recreational or medicinal use of marijuana. The exceptionally high solids-water partitioning propensity of THC makes adsorption the dominant removal mechanism, with photocatalysis potentially supporting the removal efficacy of this compound. These results indicate that MicroCuZn can be a promising oxidative catalyst especially for degradation of ECs, with possible reusability of this historically significant material with environmentally-friendly attributes.