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In recent years, data has increasingly become the "new oil" for 21st-century economic development. However, there is still a gap in how the development of big data promotes the improvement of urban carbon unlocking efficiency (UCUE). Utilizing advanced double machine learning (DML) methods, and treating the big data comprehensive pilot zone (BDCPZ) as a quasi-natural experiment, we employ panel data from 282 Chinese cities spanning 2011 to 2022 to study the impact of big data policies on UCUE and its mechanisms. The study finds that: (1) Big data policies significantly enhance carbon unlocking efficiency, and their importance in carbon unlocking is confirmed even when alternative machine learning models are used.(2) Regarding the mechanisms, big data policies improve carbon unlocking efficiency through three pathways: government modernization, enterprise intelligent development, and economic transformation.(3) Heterogeneity analysis reveals that the carbon unlocking benefits of big data policies are more pronounced in large cities, old industrial base cities, digital economy dividend cities and key environmental protection cities. We also provide insights for strengthening the construction of big data, alleviating carbon emission pressures, and achieving the goals of "dual carbon". • We use a new approach of double machine learning instead of traditional econometric models. • We explored three new path mechanisms for big data policies to enhance carbon unlocking efficiency. • We adopt rich robustness and endogeneity tests to consolidate the scientific validity of the results. • We explore the differential effects of city size, digital economy, industrial base and environmental protection. [ABSTRACT FROM AUTHOR]

Adsorption removal of PCDD/Fs from flue gas is one of the important technologies for reducing environmental PCDD/Fs emissions. However, due to the lack of systematic research on the adsorption mechanism of PCDD/Fs, commercial activated carbon (AC) with a single pore size distribution and lack of surface functional groups has poor adsorption and removal efficiency for PCDD/Fs. Therefore, this study first used corncob as a raw material and prepared N-doped hierarchical porous biochar (NHPB) using a one-step activation method for efficient removal of PCDD/Fs. The removal efficiency of NHPB for 17 toxic PCDD/Fs and 136 PCDD/Fs in simulated flue gas is as high as 96.21% and 97.21%, respectively. Compared with AC, the adsorption performance of NHPB was significantly less affected by the fluctuation of temperature and concentration than AC because the adsorption performance changed little with the chlorine substitution number of PCDD/Fs, and showed excellent adsorption performance under various adsorption conditions. Subsequently, the adsorption mechanism of PCDD/Fs on NHPB was systematically studied using theoretical calculations. Molecular simulations show that the optimal adsorption pore size for PCDD/Fs is mainly micropores above 1 nm and mesopores between 2 and 5 nm. Therefore, the hierarchical pore structure of NHPB exhibits superior adsorption performance. Density functional theory (DFT) calculations show that all three N-doping forms on the surface of biochar can enhance the adsorption energy of PCDD/Fs on biochar, thereby further enhancing the adsorption performance of NHPB for PCDD/Fs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Enhancing the coal-based fulvic acid (FA) yield through the effect of oxidation methods was of great importance. However, the realization of an efficient and environmentally friendly method for the preparation of FA, along with understanding of its formation mechanism, remains imperative. Herein, coal-based FA was prepared by oxidizing lignite with H 2 O 2 and NaOH/KOH. The experimental data showed that ML lignite was pickled with HCl, metal ions such as iron, aluminum, and calcium can be removed, and this lignite is used as raw material, the reaction time was 150 min, the reaction temperature was 50 °C, and the volume ratio of H 2 O 2 (30%) to KOH (3 mol/L) was 1:1, the effect of H 2 O 2 and KOH on FA extraction was the best. The coal-based FA yield could reach 60.49%. The addition of silicone defoaming agent during the experiment resulted in a significant diminished the presence of bubbles and prevent the production of CO 2. A decrease in N 2 content was detected by GC. The FTIR, XPS, Py-GC/MS and other characterization results showed that FA has more polar functional groups (-COOH, –OH), and it contains more O–C O structure. Consequently, a greater quantity of FA molecules is generated during the reaction process. Moreover, the partial Gibbs free energies during the formation process of coal-based FA were calculated by density-functional theory (DFT). The highest energy required for free radicals was found to be between 1.3 and 1.7 eV. This study would provide theoretical support for exploring the FA formation process and the promotion of lignite humification by adding H 2 O 2 or alkali to lignite. The hydrothermal oxidation of Yunnan lignite was carried out by adding H 2 O 2 and KOH activator to lignite by alkali dissolution acid precipitation method to obtain high content of fulvic acid. Under the action of •OH, •O 2 −, HO 2 • and other free radicals and energy, the fragmentation of C–O and C–H in lignite is promoted, and more aromatic structures are transformed into aliphatic structures. Silicone defoamer agents inhibit the oxidation of carboxyl groups to CO 2 and reduce N loss. The experimental process produces many bubbles, and the defoaming-ball enters the foam wall to form a bridge, and finally, under the uncompensated wall pressure, the foam bursts. [Display omitted] • Coal-based fulvic acid was efficiently extracted by H 2 O 2 and NaOH or KOH oxidation method. • addition of silicone defoamer reduce foam formation and inhibit the excessive oxidation of-COOH to CO 2. • The formation mechanism of fulvic acid was revealed by both experiments and DFT calculations. [ABSTRACT FROM AUTHOR]

Electrolytic manganese residue (EMR) is known for high concentrations of Mn2+, NH 4 +, and heavy metals. Failure to undergo benign treatment and landfill disposal would undeniably lead to negative impacts on the quality of the surrounding ecological environment. This study sought to mitigate the latent environmental risks associated with EMR using a cooperative solidification/stabilization (S/S) method involving coal fly ash (CFA). Leveraging leaching toxicity tests, the leaching behavior of pollutants in electrolytic manganese residue-based geopolymer materials (EMRGM) was determined. At the same time, mechanistic insights into S/S processes were explored utilizing characterization techniques such as XRF, XRD, FT-IR, SEM-EDS, and XPS. Those results confirmed significant reductions in the leaching toxicities of Mn2+ and NH 4 + to 4.64 μg/L and 0.99 mg/L, respectively, with all other heavy metal ions falling within the permissible limits set by relevant standards. Further analysis shows that most of NH 4 + volatilizes into the air as NH 3 , and a small part is fixed in the EMRGM in the form of struvite; in addition to being oxidized to MnOOH and MnO 2 , Mn2+ will also be adsorbed and wrapped by silicon-aluminum gel together with other heavy metal elements in the form of ions or precipitation. This research undeniably provides a solid theoretical foundation for the benign treatment and resourceful utilization of EMR and CFA, two prominent industrial solid wastes. [Display omitted] • The optimal formulation for preparing C-A-S-H gel using EMR and CFA is determined. • Leaching tests demonstrate the environmental friendliness of EMRGM. • The Mn2+ and NH 4 + S/S mechanisms have been analyzed and discussed. • Correlation analysis of test outcomes was conducted using the Spearman method. • Endorsement offered for the harmless and resourceful utilization of EMR and CFA. [ABSTRACT FROM AUTHOR]

Digital technology advancement provides a significant impetus to achieve China's "dual-carbon" goals, yet it also gives rise to a series of challenges. Therefore, studying the relationship between digital technology innovation and carbon emission efficiency is of paramount importance. This study theoretically analyzes and empirically tests the influence of digital technology innovation (DTI) on total factor carbon emission efficiency (TFCE) using panel data from 268 Chinese cities between 2006 and 2021. The results indicate that: (1) DTI exhibits a "U-shaped" pattern on urban TFCE, with a decrease followed by an increase. (2) Conventional technological innovation (TI) also displays a "U-shaped" relationship with TFCE, with the turning point occurring earlier than that of DTI. DTI surpasses TI in bringing about later-stage improvements in carbon emission efficiency. (3) Mechanism tests reveal that digital technology innovation indirectly affects TFCE through energy effects, technological effects, structural effects, and regulatory effects. (4) The impact of DTI on urban TFCE varies significantly due to differences in geographical location and resource endowments. (5) The development of urban polycentricity advances the turning point at which DTI enhances TFCE while amplifying both the initial "pro-carbon" effect and the subsequent "carbon reduction" effect of DTI. (6) DTI has a spatial spillover effect on urban TFCE. This study provides empirical evidence and policy recommendations for policymakers to advance the digitalization, greening, and decarbonization transformation of cities. • Digital technology innovation (DTI) exhibits a "U-shaped" pattern on urban total factor carbon emission efficiency (TFCE). • DTI outperforms conventional technical innovation in bringing about TFCE improvements. • Mechanisms include energy effects, technological effects, structural effects, and regulatory effects. • Urban spatial structure plays a moderating role. • DTI has a spatial spillover effect on urban TFCE. [ABSTRACT FROM AUTHOR]

In light of the escalating global climate risks threatening human survival, there is a global consensus on the necessity for collaborative reduction of pollutant and carbon emissions (CRPC). Within this context, digital inclusive finance (DIF) is recognized for its unique inclusiveness and digital characteristics as a critical factor in promoting environmentally friendly and sustainable development. DIF provides advantageous channels for environmental governance, thereby making the achievement of CRPC objectives feasible. However, the impact of DIF on CRPC has not been fully explored. This study employs a spatial econometric model to investigate the impact of DIF on CRPC in 278 prefecture-level cities in China from 2011 to 2020. The findings indicate that DIF has a positive impact on CRPC, with significant spatial spillover effects. The analysis highlights the pivotal mediating roles played by technology effect and electrified effect of the energy mix, while environmental regulation effect plays a moderating role. Notably, disparities in the impact of DIF on CRPC are evident, particularly in non-resource-based cities, cities with low carbon intensity, and eastern regions where spatial spillover effects are more pronounced. These experiences enrich the relevant thesis in terms of DIF on CRPC, providing a theoretical basis for formulating CRPC schemes. • DIF has a positive spatial spillover effect on CRPC. • Technology effect and electrified effect of the energy mix play mediating roles. • Environmental regulation effect plays a moderating role. • There is heterogeneity in the impact of DIF on CRPC. [ABSTRACT FROM AUTHOR]

Environmental provisions in Preferential Trade Agreements (PTAs) have increased in recent years, however, their impact on green total factor energy efficiency (GTFEE) remains underexplored. Utilizing comprehensive data on countries' engagement with PTAs' environmental provisions, along with environmental legislative information and green trade data, this study employs various quantitative and qualitative research methods to investigate heterogeneity influence, mechanism, nonlinear relationship, and combined effect of PTAs' environmental provisions on GTFEE. The empirical results indicate that: (1) Environmental provisions within PTAs significantly enhance the GTFEE of participating countries, which is more pronounced in North-South PTAs, particularly when these provisions are closely tied to trade issues. (2) Environmental provisions in PTAs improve the GTFEE by promoting environmental legislation, facilitating green goods trade, and fostering cleaner energy structures in participating countries. (3) As the number of PTAs' environmental provisions increases in participating countries, their effect on GTFEE follows a pattern of initial inhibition, followed by promotion, and ultimately insignificance. (4) The combined effect of different types of environmental provisions in PTAs reveals three primary pathways contributing to improved GTFEE: the "environment", the "environment-trade synergy", and the "trade-safeguard synergy". • Environmental provisions in trade agreements can enhance energy efficiency. • The impact is more pronounced in North-South PTAs and provisions tied to trade issues. • Environmental provisions can improve energy efficiency through three pathways. • Different environmental provisions can be combined to improve energy efficiency. [ABSTRACT FROM AUTHOR]

Education expenditure is essential in mitigating air pollution, but the relationship between education expenditure and air pollution lacks in-depth discussion. Utilizing data at the county level in China during 2007–2021, this study estimates the effect of education expenditure from local governments on air pollution. Our findings demonstrate that education expenditure significantly and negatively affects air pollution, which remains robust after addressing endogeneity. The mechanism analysis presents that education expenditure reduces air pollution through the composition, technique, and income effects. The heterogeneity analysis indicates that the impact of education expenditure exhibits marked regional heterogeneity. Specifically, the role of education expenditure is significant in strong regulation, key, eastern, and central regions. By considering interaction terms, we identify the moderating effects of human capital, economic development, infrastructure construction, and public service for education expenditure. The cost-benefit analysis emphasizes that education expenditure improves social welfare. Our findings can inspire local governments to place more emphasis on air quality and public education expenditure. • We explore the effect of education expenditure on PM 2.5 concentration. • County-level panel data covering 28 provinces from 2007 to 2021 are employed. • Education expenditure reduces PM 2.5 concentration through composition, technique, and income effects. • Socioeconomic factors exert moderating effects on the role of education expenditure. [ABSTRACT FROM AUTHOR]

In the global wave of digitization, digital economic agglomeration, as an emerging model, profoundly impacts the economy, environment, and society. Countries worldwide are formulating strategies and policies to promote the development of digital economic agglomeration, yet they also face challenges of widening digital divide and environmental sustainability. Existing research primarily focuses on the positive effects of the digital economy, with limited assessment of the dual effects of digital economic agglomeration on sustainable development. This study utilizes panel data from 282 Chinese cities between 2011 and 2021, employing a two-tier stochastic frontier model. It reexamines the dual impacts and intrinsic mechanisms of digital economic agglomeration, attempting to capture regional and temporal variations in the dual effects to address this research gap. The study shows that: (1) The positive effect of digital economy agglomeration is much more than the negative effect, resulting in a positive net effect that shows an overall increasing trend with significant regional disparities. (2) Digital economic agglomeration has a significant negative spatial spillover effect, promoting local inclusive green growth while inhibiting inclusive green growth in neighboring cities. (3) Regarding the mediating mechanisms, industrial structure, technological innovation and resource allocation efficiency have positive indirect effects on inclusive green growth, while environmental regulation intensity has a negative indirect effect, and it has a nonlinear effect under the threshold constraint of the mediating mechanisms. This study provides policy insights for promoting inclusive green growth, emphasizing the need to consider regional differences in resource distribution, ecological environment, and social demands. It advocates for the organic integration of the digital economy across different regions, reducing polarization effects, and enhancing diffusion effects. • Digital economy agglomeration has a dual effect on inclusive green growth. • This study verifies the impact mechanism of digital economy agglomeration on inclusive green growth. • Constrained by the threshold of mechanism variables, digital economy agglomeration has a nonlinear effect. • Digital economy agglomeration has a negative spatial spillover effect. [ABSTRACT FROM AUTHOR]

Combating climate change and reducing carbon dioxide emissions are serious challenges shared by countries around the world. In the current era, digitalization has a significant impact on CO 2 emissions. However, prior studies have not assessed the synergy between digitalization and industrialization on carbon emission performance. The principal component analysis and non-radial directional distance function (NDDF) are used to measure the digitalization and total factor carbon emission performance of Chinese 245 prefecture-level cities from 2003 to 2019. This study establishes a fixed effects model to study the panel data. The findings are as follows: (1) Digitalization can significantly promote Chinese cities' CO 2 emission reduction. This result still holds after several robustness checks. (2) The heterogeneity results indicate that digitalization mainly improves central cities' carbon emission performance. Meanwhile, the impact of digitalization is more obvious after 2011. (3) Digitalization improves urban carbon emission performance through energy efficiency, industrial transformation, and technological innovation. (4) It is worth noting that digitalization synergizes with industrialization to improve carbon emission performance in Chinese cities. This study provides empirical evidence and some constructive policy recommendations for the government to push the collaborative development of the digitalization and low-carbon economy. [Display omitted] • This paper uncovers the synergistic effect of digitalization and industrialization on cities' carbon emission performance. • We measure urban digitalization level and total factor carbon emission performance. • There are three influencing mechanisms including energy efficiency, industrial transformation, and technological innovation. • Digitalization synergizes with industrialization to enhance carbon emission performance in Chinese cities. • Some constructive policy recommendations are proposed for pushing the cities' low-carbon transformation. [ABSTRACT FROM AUTHOR]

Understanding the significance of financial clustering in the context of green development holds immense importance for China as it strives towards achieving high-quality green development. Using a balanced panel dataset encompassing China's 283 cities from 2009 to 2020, we aim to explore the impact of financial clustering on green development from both linear and nonlinear perspectives. Empirical evidence suggests that when the level of financial clustering increases by 1%, the city-level green development increases by 0.1012%. A mediation effect model certifies that there are three essential channels through which financial clustering robustly boosts green development: technical, structural and scale effects. Subsequently, a novel program handling endogeneity is designed and verifies the nonlinear nexus between financial clustering and green development. Moreover, the spatial Durbin model demonstrates that financial clustering significantly sustains local green development, despite its relatively weak spill over effects. Heterogeneity analysis presents that the promoting effect is particularly predominant in Central China, as well as in cities characterized by high levels of financial clustering and large population sizes. • Financial clustering (FC) significantly boosts green development (GD). • FC affects GD through the technical, structural and scale effects. • FD exhibits significant nonlinear effects on GD. • FD not only boosts local GD but also significantly promotes neighbouring GD. [ABSTRACT FROM AUTHOR]

As a momentous policy tool for spatial management, urban administrative boundary expansion (UABE) significantly impacts resource reorganization and development modes. However, the environmental effects of UABE are easily ignored. Whether UABE can also impove the environmental quality in addition to its economic effects remains to be answered. To fill this gap, we took the city-county merger policy (CCMP) in China as quasi-experimental evidence and empirically investigated the impacts of CCMP on air pollution based on the difference-in-difference method. The impact mechanisms were also analyzed from a whole-process perspective. The results demonstrate that, apart from expanding the urban scale, UABE can improve urban air quality as well. Further analysis shows that the positive effect is mainly realized by source control and process management, rather than end-of-pipe treatment. Besides, the impacts of UABE on air pollution exhibit obvious spatial heterogeneous characteristics. We also reported that the environmental effects of UABE are largely dependent on governmental control, rather than market factors. According to the results above, flexible administrative boundary adjustment, strict government regulations, and effective market systems are required to realize the dual goals of environmental improvement and space optimization. [Display omitted] • We test the effects of urban administrative boundary expansion (UABE) by DID model. • Apart from economy, air quality can also be improved by UABE. • UABE controls air pollution from the source, rather than by terminal treatment. • The environmental effect of UABE largely depends on government control. • The impact of UABE on air pollution has significant spatial heterogeneity. [ABSTRACT FROM AUTHOR]

The effectiveness of campaign-style enforcement (CSE) on water pollution, especially the long-term effectiveness, is controversial, and little knowledge is known about the channels through which the effectiveness happens. We take advantage of China's Environmental Protection Interview (EPI)— a distinguished form of CSE launched in 2014, as a natural experiment to estimate the short-term and long-term effects of CSE on water pollution. Using a time-varying difference-in-differences model based on city panel data from 2006 to 2018, we find that EPI can lead to an average 14.5% reduction in water pollution, and this effect is still persistent in the long term. Mechanism analysis shows that EPI reduces water pollution mainly through the pressure effect on the government, the penalty effect on the firms, and the mobilization effect on the public. Heterogeneity analysis shows that the effect of EPI on water pollution is more significant in cities with high initial pollution, low public complaints, and low economic levels. Further cost-benefit analysis based on the estimated value of water pollution reduction shows that the upper health benefit of EPI is $520.97 billion, which is 4.87 times higher than its estimated cost of $107.05 billion. [Display omitted] • We take China's Environmental Protection Interview (EPI) as a natural experiment. • We estimate the short-term and long-term effects of EPI on water pollution. • EPI can lead to an average 14.5% reduction in water pollution. • EPI reduces water pollution mainly through pressure effect, penalty effect, and mobilization effect. [ABSTRACT FROM AUTHOR]