Photocatalytic degradation of organic pollutants in wastewater is recognized as a promising technology. However, photocatalyst Bi₂O₃ responds to visible light and suffers from low quantum yield. In this study, the α-Bi₂O₃ was synthetized and used for removing Cl⁻ in acidic solutions to transform BiOCl. A heterostructured α-Bi₂O₃/BiOCl nanosheet can be fabricated by coupling Bi₂O₃ (narrow band gap) with layered BiOCl (rapid photoelectron transmission). During the degradation of Rhodamine B (RhB), the Bi₂O₃/BiOCl composite material presented excellent photocatalytic activity. Under visible light irradiation for 60 min, the Bi₂O₃/BiOCl photocatalyst delivered a superior removal rate of 99.9%, which was much higher than pristine Bi₂O₃ (36.0%) and BiOCl (74.4%). Radical quenching experiments and electron spin resonance spectra further confirmed the dominant effect of electron holes h⁺ and superoxide radical anions ·O₂⁻ for the photodegradation process. This work develops a green strategy to synthesize a high-performance photocatalyst for organic dye degradation.

Lepidolite, crucial for lithium extraction, is primarily processed through flotation. However, conventional flotation inhibitors pose environmental challenges. This study introduces Fe(III) as a selective and eco-friendly inhibitor in lepidolite flotation. We investigated its impact on flotation performance and interaction mechanisms with feldspar, quartz, and lepidolite. Adsorption studies revealed that dodecylamine (DDA) selectively adsorbs onto lepidolite when Fe(III) is present. Consistent contact angle and flotation results showed reduced hydrophobicity and recovery rates for feldspar and quartz, with minimal impact on lepidolite. Zeta potential measurements indicated lower potentials for feldspar and quartz compared to lepidolite. Notably, the addition of Fe(III) altered the isoelectric points of quartz and feldspar, suggesting stronger Fe(III) adsorption on these minerals. Infrared spectroscopy and X-ray photoelectron spectroscopy confirmed reduced DDA adsorption on feldspar and quartz surfaces due to Fe(III) adsorption, while DDA adsorption on lepidolite remained largely unaffected. The mechanism underlying Fe(III)’s selective inhibition on feldspar and quartz involves their more negative surfaces compared to lepidolite, which facilitates Fe(III) adsorption and inhibits DDA adsorption. This study offers insights into mechanisms relevant to systems using metal ions as depressants, providing valuable references for similar research.

Chitosan (CS) is a natural and low-cost adsorbent for capturing metal ions and organic compounds. However, the high solubility of CS in acidic solution would make it difficult to recycle the adsorbent from the liquid phase. In this study, the CS/Fe₃O₄ was prepared via Fe₃O₄ nanoparticles immobilized onto a CS surface, and the DCS/Fe₃O₄-Cu was further fabricated after surface modification and the adsorption of Cu ions. The meticulously tailored material displayed the sub-micron size of an agglomerated structure with numerous magnetic Fe₃O₄ nanoparticles. During the adsorption of methyl orange (MO), the DCS/Fe₃O₄-Cu delivered a superior removal efficiency of 96.4% at 40 min, which is more than twice the removal efficiency of 38.7% for pristine CS/Fe₃O₄. At an initial MO concentration of 100 mg L⁻¹, the DCS/Fe₃O₄-Cu exhibited the maximum adsorption capacity of 144.60 mg g⁻¹. The experimental data were well explained by the pseudo-second-order model and Langmuir isotherm, suggesting the dominant monolayer adsorption. The composite adsorbent still maintained a large removal rate of 93.5% after five regeneration cycles. This work develops an effective strategy to simultaneously achieve high adsorption performance and convenient recyclability for wastewater treatment.

A new type of amino acid surfactant, lauroyl lysine (LL), is used as a green collector for the low-temperature flotation of quartz. The micro-flotation test results indicate that, under flotation conditions of 10–40 °C, pH = 11.0, 20 mg/L CaCl₂, and 60 mg/L LL, the highest recovery of quartz by LL could reach up to 97.08%. The temperature at which flotation occurs little impacts LL collection efficiency. In contrast, sodium oleate (NaOL) gives inferior performance to LL at all tested temperatures. The adsorption measurement and SEM-EDS results confirm that a quantity of LL is absorbed onto the quartz surface at low temperatures. Investigations into the interaction between the reagents and mineral surfaces are conducted using X-ray photoelectron spectroscopy (XPS) analysis, zeta potential measurements, and Fourier transform infrared (FT-IR) spectra. Findings indicate that LL is adsorbed onto the quartz surface through hydrogen bonds and intense chemisorption. Additionally, the amide groups in the LL molecular structure increase the solubility of the collector at low temperatures, and simultaneously, the amide bond can form an intermolecular hydrogen bond between O and H, which is conducive to quartz flotation.