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Abstract Economic development and urban expansion have accelerated particulate matter pollution in urban areas in China. Particulate matter-driven haze poses a serious threat to human beings from a public health point of view. Substantial evidences had linked adverse health effects with exposures to PM 2.5 , but recent research indicated that PM 10–2.5 also had great risk. However, the relative contributions of driving forces to PM 10–2.5 pollution are not well understood in the urban areas in China, and no targeted policies have been regulated to control the pollution. In this study, we quantified the contributions of potential driving factor across China with the structural equation model (SEM). Our results showed that in 2015 and 2016, the annual average concentrations of PM 10–2.5 in the 290 prefecture-level cities with a mean value of 36 and 35 μg/m3, respectively. Industrial scale contributed more to PM 10–2.5 pollution than city size and residents' activities in urban areas based on SEM results. Driving forces included in our model could explain 42% of variations in PM 10–2.5 pollution, which indicated that there existed influences from other anthropogenic sources and natural sources. Eleven targeted recommendations were then proposed to control PM 10–2.5 pollution based on our mechanism analysis. Findings from our study are beneficial to control PM 10–2.5 pollution on a national scale, and also can provide a theoretical basis for the formulation of PM 10–2.5 pollution control policy in China. Graphical abstract Unlabelled Image Highlights • PM 10–2.5 poses a serious threat to human beings from a public health point of view. • Structural equation model is used to determine the driving mechanisms. • Urban PM 10–2.5 pollution was concentrated in central regions of China. • Industrial scale contributed most to PM 10–2.5 pollution in urban areas. • Eleven recommendations to control PM 10–2.5 pollution are proposed. [ABSTRACT FROM AUTHOR]

Polydopamine microspheres (PDMPs) synthesized by a facile solution oxidation method were adopted as a potential adsorbent for the removal of Norfloxacin (NOR) from aqueous solution. The morphologies and properties of PDMPs were characterized using TEM, SEM, FTIR and pH PZC . Parameters effects such as contact time, initial pH, initial concentration and ionic strength on the adsorption capacity of NOR onto PDMPs were studied. To maximize NOR removal from liquid phase, Box–Behnken experimental design (BBD) combined with response surface modeling (RSM) was employed based on the 17 preliminary experiments at 308 K. Optimum contact time, initial NOR concentration and initial pH value were found to be 97 min, 303 mg·L −1 and 6.6, respectively, the corresponding NOR removal capacity was found to be 307 mg·g −1 . Batch adsorption experiments under the optimal conditions were conducted to investigate kinetics, thermodynamics and adsorption isotherm. Kinetic analysis confirmed that the kinetic data were well described by Pseudo-second order model. The experimental equilibrium data were well fitted by Langmuir, Redlich-Peterson, Koble-Corrigan and Dubinin-Radushkevich models. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy were calculated and the results indicated that the NOR adsorption onto PDMPs was spontaneous and endothermic. The adsorption process may be attributed to the electrostatic interaction, the formation of hydrogen bonds or π-π stacking interactions among the polydopamine (PDA) and NOR molecule. [ABSTRACT FROM AUTHOR]

Producing a desirable adsorbent for removing endocrine disrupting compounds (EDCs) from aqueous solutions remains a major challenge. In this work, microporous-dominated nitrogen-doped framework carbons (MNFCs, s means the calcination temperature) with high specific surface area, ultra-microporous structure, and high nitrogen-doping can be obtained by a direct calcination of ethylene diamine tetraacetic acid tetrasodium (EDTA-4Na) without aid of any catalyst and nitrogen source. MNFCs were applied adsorbents to remove bisphenols from aqueous solution. Batch experiments showed MNFC-750 had a large adsorption capacity for bisphenols from aqueous solutions (409 mg/g for bisphenol A, 364 mg/g for bisphenol F, and 521 mg/g for bisphenol S) along with short equilibrium time (30 min), and good stability and reusability. Using multiple characterizations and comparative experiments along with theoretical calculations, we discovered that: (1) nitrogen-doping can significantly boost the adsorption capacity; (2) adsorption sites are mainly the pyridinic-N instead of pyrrolic-N and graphitic-N; and (3) the adsorption mechanisms were mainly driven by Lewis acid-base interaction, hydrophobic interaction, π-π interaction and hydrogen bond interaction. These findings indicate that MNFCs present a promising potential for practical applications and shed light on the rational design of nitrogen doped carbon-based adsorbents for efficient pollutant removal. Unlabelled Image • Microporous-dominated nitrogen-doped framework carbons (MNFCs) were fabricated. • MNFC-750 had high adsorption capacity, short equilibrium time and good reusability. • Nitrogen doping onto MNFC-750 can significantly boost the adsorption capacity. • Adsorption sites were mainly the pyridinic-N. [ABSTRACT FROM AUTHOR]

Heavy metal pollution has posed a potential hazard to the ecological environment and human health. Herein, a novel ternary magnetic adsorbent (Fe 3 O 4 /g-C 3 N 4 /Carbon layer, Carbon layer: hydrothermal products from sucrose) was synthesized through a simple hydrothermal carbonization (HTC) method for removal of hexavalent chromium (Cr (VI)) removal. The Carbon layer (CL) formed during the HTC of carbon precursors (sucrose) acted as a reducing agent. Also, it has abundant oxygen-containing groups on its surface. The Fe 3 O 4 /g-C 3 N 4 /CL had a high removal capacity for Cr (VI) (50.09 mg/g), and excellent regeneration and magnetic separation performance. Importantly, the Fe 3 O 4 /g-C 3 N 4 /CL could not only improve the adsorption ability for Cr (VI), but also strengthen the immobilization of Cr (III). Based on the comprehensive experiments and characterization, combined with DFT calculations, we proposed that, the first time, the removal of Cr (VI) was controlled by three consecutive processes: (1) ion exchange of Cr (VI) by hydroxyl groups, (2) reduction of Cr (VI) to Cr (III) by electron-donor (oxygen-containing) groups (EDGs), and (3) complexation of Cr (III) by amine groups. This study provides a new avenue for the removal of toxic oxygen anions and reveals an original removal mechanism of Fe 3 O 4 /g-C 3 N 4 /CLx (x = hydrothermal products from carbon precursors (glucose, ascorbic acid, cellulose)). Unlabelled Image • A novel ternary Magnetic Fe 3 O 4 /g-C 3 N 4 /Carbon layer composite was fabricated. • The composite had high removal capacity for Cr (VI) and regeneration performance. • The composite had high Cr (VI) adsorption and Cr (III) immobilization. • New insight of Cr (VI) removal is the synergy of ion exchange, reduction and complexation. [ABSTRACT FROM AUTHOR]