This study prepares a novel phosphorene (PN) and loads it onto TiO₂ to fabricate PN-TiO₂ and effectively photodegrade the hydrophobic environmental hormone 17β-estradiol in aqueous solutions. The effect of the PN on degradation efficiency is systematically investigated. It is observed that the doping of TiO₂ with PN significantly enhances its photocatalytic and adsorption properties compared with that in the absence of PN; that is, the addition improves the adsorption capability of the composite. The optimal PN weight content is found to be 0.5%. The performance of the PN-TiO₂ photocatalyst in degrading E2 is around 67.5%. However, its photodegradation efficiency gradually decreases when the PN content is further increased. This optimal PN content directly suggests synergistic interactions affecting the photodegrading efficiency. Compared with other PN-based photocatalysts mentioned in the literature, this PN-based material possesses striking advantages, such as higher energy efficiency, greater removal capacity, and superior cost-effectiveness. Further, the decrease in the biotoxicity of the water after treatment is evident in observing the development of zebrafish embryos. The studies of the catalyst performed on the zebrafish show that it results in a higher mortality rate at 96 h with a superior hatching rate and healthy fish development. In summary, the prepared PN-based materials exhibited promising photocatalytic capabilities for the removal and biotoxicity reduction of 17β-estradiol in aqueous solutions.

Large amounts of wastewater are generated from stone processing, which are toxic and cause serious environmental and health risks. To quantify the content of stone processing wastewater and estimate its effects on plant growth, we collected water samples from sewage outfall of four stone processing factories and nearby water bodies. The concentration of potential toxic metals were much higher in the wastewater than background controls. Wastewater inhibited plant primary root elongation, lateral root formation, and growth of aerial part. Seedlings treated with the effluents were unhealthy with deep purple leaves and usually died before flowering. Chlorophyll a/b contents and chloroplast number were reduced in those abnormal mesophyll cells. Transcriptional levels were decreased for chloroplast formation genes, but increased for those participated in chloroplast degradation and catabolism. Six out of nine tested senescence-associated genes were up-regulated. Furthermore, our results show that endogenous toxic metal levels indeed increased after wastewater treatment. Altogether, these results indicated that the potential toxic metals rich wastewater had significant inhibition on plant growth and led to senescence-associated program cell death, which could be helpful for the government and enterprises to understand the environmental risks and formulate reasonable wastewater emission standards for the stone processing industry.