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

• Published in: RSC advances Vol. 1; no. 65; pp. 39931 - 39942
• Main Authors: Ramirez-Sanchez, Irwing M, Apul, Onur G, Saleh, Navid B
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 02-11-2020; The Royal Society of Chemistry
• Subjects: Alloys; Brasses; Catalytic activity; Chemistry; Contaminants; Copper; Decay rate; Degradation; Hydrogen peroxide; Hydroxyl radicals; Marijuana; Morphology; Photocatalysis; Photoelectrons; Pollutants; Recreational use; Terephthalic acid; Ultraviolet radiation; Zinc; Zinc base alloys; Zinc oxide
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d0ra06153k

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 (&z.rad;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 &z.rad;OH is monitored with
N
,
N
-dimethyl-4-nitrosoaniline (
p
NDA) and terephthalic acid (TA), which are effective &z.rad;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.
Micron-scale brass is a catalyst that can be activated with ultraviolet radiation to remove emerging contaminants from water
via
oxidation by hydroxyl radicals.