The lack of access to clean water remains a severe issue all over the world. Coupling photocatalysis with the membrane separation process, which is known as a photocatalytic membrane reactor (PMR), is promising for water treatment. PMR has developed rapidly during the last few years, and this paper presents an overview of the progress in the configuration and operational parameters of PMRs. Two main configurations of PMRs (PMRs with immobilized photocatalyst; PMRs with suspended photocatalyst) are comprehensively described and characterized. Various influencing factors on the performance of PMRs, including photocatalyst, light source, water quality, aeration and membrane, are detailed. Moreover, a discussion on the current problems and development prospects of PMRs for practical application are presented.

Corporate energy consumption and emissions are major contributors to pollution and greenhouse gas emissions. Therefore, corporate energy conservation and emission reduction are essential for sustainable development and low-carbon transformation in China. With pressing global environmental issues and the mounting pressure for carbon neutrality, it is increasingly important for firms to disclose environmental information. However, research on the relationship and mechanisms between corporate environmental information disclosure (EID) and corporate performance is insufficient. This study examines the effect of EID on corporate environmental performance (EP) and financial performance (FP) using a two-way fixed-effect model. For this purpose, this study considers the panel data of 1125 Chinese A-share listed companies from 2009 to 2021. Additionally, we explore the underlying mechanisms using mediation models. The results reveal that EID can significantly improve corporate performance through green innovation (GI). Moreover, EID can enhance corporate GI, which improves the financial performance of high-polluting firms and the environmental performance of non-high-polluting firms. According to these results, it is imperative to continuously improve corporate EID systems and encourage GI in enterprises. Thus, firms should take the initiative to disclose environmental information. There is a pressing need to enhance the effectiveness of the capital market, therefore, firms with higher levels of EID and better environmental performance can gain greater benefits.

Improving air quality is an urgent task for the Beijing–Tianjin–Hebei (BTH) region in China. In 2018, utilizing 365 days’ daily concentration data of six air pollutants (including PM_2.5, PM₁₀, SO₂, NO₂, CO and O₃) at 947 air quality grid monitoring points of 13 cities in the BTH region and controlling the meteorological factors, this paper takes the implementation of the Blue Sky Defense War (BSDW) policy as a quasi-natural experiment to examine the emission reduction effect of the policy in the BTH region by applying the difference-in-difference method. Results show that the policy leads to the significant reduction of the daily average concentration of PM_2.5, PM₁₀, SO₂, O₃ by −1.951 μg/m³, −3.872 μg/m³, −1.902 μg/m³, −7.882 μg/m³ and CO by −0.014 mg/m³, respectively. The results of the robustness test support the aforementioned conclusions. However, this paper finds that the concentration of NO₂ increases significantly (1.865 μg/m³). In winter heating seasons, the concentration of SO₂, CO and O₃ decrease but PM_2.5, PM₁₀ and NO₂ increase significantly. Besides, resource intensive cities, non-key environmental protection cities and cities in the north of the region have great potential for air pollutant emission reduction. Finally, policy suggestions are recommended; these include setting specific goals at the city level, incorporating more cities into the list of key environmental protection cities, refining the concrete indicators of domestic solid fuel, and encouraging and enforcing clean heating diffusion.

In the actual water environment, the health risk of waterborne viruses is evaluated to be 10¹–10⁴ times higher at a similar level of exposure compared with bacteria and has aroused strong concern in many countries in the world. Photocatalytic membrane reactor (PMR), a new process for virus inactivation in water, has gradually become one of the main tools to inactivate pathogenic organisms in water. However, there is relatively little attention to the effect of natural organic matters (NOMs) on the PMR system, which actually exists in the water environment. In this paper, the TiO₂-P25, a common type in sales and marketing, was selected as the photocatalyst, and humic acid was regarded as the representative substance of NOMs for investigating thoroughly the influence of humic acid on virus removal by the PMR system. It was found that competitive adsorption between the virus and humic acid occurred, which markedly reduced the amount of virus adsorbed on the surface of the photocatalyst. Moreover, with humic acid, the direct contact behavior between the virus and the photocatalyst was blocked to some extent, and the disinfection of phage f2 by the active free radicals produced by photocatalysis was furthermore badly affected. Meanwhile, the special structure of humic acid, which made humic acid be able to absorb light of 270–500 nm, led to the reduction of photocatalytic efficiency. Further experiments showed that when there was a certain concentration of humic acid in water, intermittent operation mode or higher membrane flux (>40 L/(m²·h)) was selected to partly alleviate the adverse effects of humic acid.