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As a means of producing the resources required for human survival and development, land is the cornerstone of social development and an important part of the ecological environmental system. To measure the granularity and spatial differentiation of changes in the ecological security levels of the study area, this paper uses the PSR model. A kilometer grid is used as the evaluation unit, and a relative entropy theory is used to obtain the combined weight. The comprehensive index method is used to calculate the ecological security value of the land. Based on clarifying the dynamics of time and space, the spatial distribution of the ecological security levels in 2020 is simulated by the CA-Markov model. The results show the following: (1) the level of ecological security in the city of Deyang decreases from 0.580 in 2005 to 0.558 in 2015, showing a fluctuating downward trend, and different districts, cities, and counties and show varying trends. (2) During the study period, the area classified with a safe level decreased from 2853.72 km2 in 2005 to 1809.45 km2 in 2015, and the areas with critical safe, less safe, and unsafe levels all increased. The areas of decrease are mainly concentrated in the Jingyang District, Luojiang County, and Zhongjiang County. (3) The results of four proposed scenarios for future economic or environmental development are significantly different. Maintaining the status quo cannot change the declining trend in ecological security in the city of Deyang. A priority of economic development will lead to a significant decline in land ecological security. Establishing environmental protection as a priority can significantly change the ecological security of the land in the city. The results of the “comprehensive” scenario simulation are closest to the actual security values calculated for 2019, reflecting the trade-off between economic development and environmental protection. The research results can provide a reference for the evaluation and prediction of ecological security and provide theoretical guidance for the formulation of sustainable measures.

A durable and high-flux superhydrophilic-underwater superoleophobic oil-water separation membrane was prepared for effective oil-water separation by cellulose-starch-silica surface charging and hydrophilization. The surface properties of the composite coating nylon membrane were characterized by contact angle and scanning electron microscopy. The chemical structures of this membrane were confirmed by Fourier transform infrared spectroscopy and energy dispersive X-ray spectrometer. This membrane showed excellent hydrophilicity and underwater oleophobicity. After modified, the water contact angle of the membrane attained 0, and the underwater oil contact angles reached 159.5. The cellulose-starch-silica composite coating nylon membrane exhibited high oil-water separation efficiency (99.8%) for hexane, and it was also efficient for cyclohexane, petroleum ether, diesel, soybean oil, lubricating oil and silicone oil. Besides, the membrane flux could reach 31847 L−1m−2 h−1 bar−1. It showed this membrane had a high efficiency for oil-water separation. The modified nylon membrane was durable for oil-water separation. The separation efficiency could still retained above 97% after 100 cycles, and the modified nylon membrane still worked well after 24 h in harsh environment (pH value 4 to 10). The whole separation process could be achieved successfully without depending on any extra power. This work provided a new strategy to fabricate superhydrophilic and underwater superoleophobic membrane with good reusability, high flux and stability for oil-water separation.

For the first time, a heterostructure was synthesized by bismuth oxychloride and Zn-Cr layered double hydroxide. A novel membrane photocatalyst was then obtained by dispersing the heterostructure in polyvinylidene fluoride. Under visible light, the membrane removed 99.9% of Rhodamine B after 240 min. Under sun light, the removal even reached over 80% after 360 min. The heterostructure effectively inhibited the recombination of electron–hole pairs and promoted the production of active species, thus improving the natural-light activity. The degradation mechanism for Rhodamine B was attributed to photocatalysis and photosensitization. Moreover, the formation of membrane improved the reusage of photocatalyst. Therefore, this work put forward a potential natural-light photocatalyst for a real application.