Z-scheme CuO/Fe3O4/GO heterojunction photocatalyst: Enhanced photocatalytic performance for elimination of tetracycline.

CuO/Fe3O4/GO, as a Z-scheme heterojunction catalyst, was successfully synthesized and used as a photocatalyst for removing tetracycline from aqueous solution. The CuO/Fe3O4/GO heterogeneous catalyst combines the narrow bandgap semiconductor CuO, oxygen vacancies of Fe3O4, and oxygen-containing reaction sites of GO. Without the addition of activators (persulfate or H2O2), the photocatalytic performance on decomposing tetracycline is very excellent. Compared with GO, Fe3O4, and CuO, CuO/Fe3O4/GO exhibits superior photocatalytic performance. Under visible light radiation, CuO/Fe3O4/GO generates h+ and ⋅O2-, which are the mainly responsible active groups for TC degradation. The effects of various pH, catalysts, and reuse on the degradation performance are evaluated, and the optimal conditions for CuO/Fe3O4/GO removal of tetracycline are obtained at pH 7, catalyst dosage 20 mg⋅L-1, TC at a concentration of 30 mg/L, nearly 97.3% of tetracycline is decomposed. This study has great potential in the treatment of wastewater containing various antibiotics.

Gemini surfactant: A novel flotation collector for harvesting of microalgae by froth flotation.

Froth flotation has been proved to be a promising approach for commercial scale harvesting of microalgae. However, all the surfactants used in the microalgae flotation harvesting process are conventional monomeric surfactants contain a single similar hydrophobic group in the molecule, which results in a low harvesting efficiency. In this work, a novel Gemini surfactant, N,N'-bis(cetyldimethyl)-1,4-butane diammonium dibromide (BCBD) was prepared, and originally recommended as a collector for froth flotation harvesting of Chlorella vulgaris from culture medium. The performance of BCBD was compared with the results acquired using its conventional monomeric surfactant cetyl trimethyl ammonium bromide (CTAB). The bench-scale flotation results showed that BCBD had excellent collecting power for Chlorella vulgaris. Achieving the obviously superior flotation harvesting performance (flotation recovery increased by 21.4% and enrichment ratio increased by 22.9), the dosage of Gemini type BCBD collector is five times less than that of monomeric CTAB collector.

Morpholine-Based Gemini Surfactant: Synthesis and Its Application for Reverse Froth Flotation of Carnallite Ore in Potassium Fertilizer Production.

Potassium fertilizer plays a critical role in increasing the food production. Carnallite is concentrated by reverse froth flotation and used as a raw material to produce potassium fertilizer (KCl) in agriculture. However, all the surfactants used in the carnallite reverse flotation process are conventional monomeric surfactants contain a single similar hydrophobic group in the molecule, which results in a low production efficiency. In this work, a new morpholine-based Gemini surfactant, 1,4-bis (morpholinododecylammonio) butane dibromide (BMBD), was prepared and originally recommended as a collector for reverse froth flotation separation of halite (NaCl) from carnallite ore. The flotation results indicated BMBD had higher flotation recovery and stronger affinity of halite against carnallite compared with conventional monomeric surfactant N-(n-Dodecyl) morpholine (DDM). Fourier transform infrared spectra suggested that BMBD molecules were adsorbed on halite surface rather than the carnallite surface. Additionally, BMBD molecules can strongly reduce the surface tension of NaCl saturated solution. Considering the BMBD's unique properties, such as double reactive centers to mineral surfaces, double hydrophobic groups, and stronger surface tension reducing ability, made it be a superior collector for reverse flotation desalination from carnallite ores than DDM.