No abstract

Zinc containing organic materials were synthesized using dairy wastewater and solid zinc waste derived from zinc nitrate with the goal of obtaining biodegradable, slow release, micronutrient containing fertilizers. The developed synthesis procedure involved heating at mild 55 °C temperature, followed by pH adjustment to 7, precipitation, and drying. The resulting solid materials were characterized using weight analysis, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FTIR). Higher wastewater-to-zinc nitrate ratios of 1: 1 / 5 yielded amorphous materials with no inorganic zinc compounds detected. TGA analysis showed very complex thermal behavior due to the large amount of organics present while FTIR analysis suggested the presence of both coordinated and uncoordinated carboxylic acid and ester groups. The developed process can have a variety of applications in recovering Zn from waste sources, such as tire crumb, while returning this valuable micronutrient into soil as a slow release biodegradable fertilizer.

CuZnSnS (CZTS) quantum dots (QDs) have potential application in quantum dot sensitized solar cells (QDSSCs); however, traditional synthesis approaches typically require elevated temperatures, expensive precursors, and organic solvents that can hinder large-scale application. Herein we develop and utilize an enzymatic, aqueous-phase, ambient temperature route to prepare CZTS nanocrystals with good compositional control. Nanoparticle synthesis occurs in a minimal buffered solution containing only the enzyme, metal chloride and acetate salts, and l-cysteine as a capping agent and sulfur source. Beyond isolated nanocrystal synthesis, we further demonstrate biomineralization of these particles within a preformed mesoporous TiO2 anode template where the formed nanocrystals bind to the TiO2 surface. This in situ biomineralization approach facilitates enhanced distribution of the nanocrystals in the anode and, through this, enhanced QDSSC performance.

ZnS, ZnxCd1−xS, and ZnxCd1−xS–ZnS quantum dots were synthesized in the aqueous phase at room temperature via biomineralization enabled by a single enzyme in solution.