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[Display omitted] • Summarizing the adsorption behavior of montmorillonite adsorbent through machine learning. • Predicting the removal effect of other pollutants based on GBDT model. • Establishing a model of SMZ adsorption by montmorillonite-based adsorbent. • Judging the possible interaction between adsorbent and pollutant using DFT. Montmorillonite, as a natural mineral adsorption material that has high research value in water pollution treatment. However, the adsorption capacity varies depending on the type of pollutant and the properties of the montmorillonite material, and the factors controlling adsorption are not yet clear. Herein, we investigated the adsorption behavior of pollutants on montmorillonite materials using density functional theory (DFT) calculations and machine learning modeling. Furthermore, it explores the main factors influencing their adsorption. The machine learning results indicate that the gradient boosting decision tree (GBDT) model exhibits a better fit to the experimental data compared to the other five machine learning models (R2 = 0.79). The higher pH levels and larger relative molecular mass of pollutants have a positive impact on montmorillonite adsorption. However, an increase in the proportion of oxygen atoms in the adsorbent material and longer hydrothermal preparation time show a trend of initially positive and then negative effects on the predicted results. The influence of pH on the adsorption capacity of montmorillonite adsorbents was further analyzed using density functional theory (DFT). Density functional theory (DFT) studies reveal that montmorillonite primarily removes protonated sulfamethoxazole (SMZ) through hydrogen bonding (N-H...O) interactions, accompanied by van der waals (O-O) and ionic bond (C-O...Al) forces under different pH conditions. The partial density of states (PDOS) reveals that the LUMO orbital of montmorillonite has a higher electron accepting ability than the HOMO orbital of SMZ (p orbital peak is greater than the S orbital) in the actual electron transfer process. This study provided some support for the investigation of montmorillonite-based adsorbent materials through the combination of machine learning and theoretical calculations. [ABSTRACT FROM AUTHOR]

Porous carbon is an extensively used adsorbent for the removal of dye. However, the conventional high-temperature carbonization and activation method with prolonged heating and annealing process was complicated, energy-consuming and polluting, which greatly limit the large-scale production. In this study, rapid and efficient preparation of porous carbon by the Flash Joule heating (FJH) method was realized for the first time using three bituminous coal samples with different degrees of metamorphism. The preparation process was completed in less than 1 s without chemical treatment, the process was more environmentally friendly. The physical and chemical properties of porous carbon were analyzed and the adsorption mechanism of porous carbon on methylene blue (MB) was investigated. The results showed that the specific surface area of porous carbon prepared by Shuozhou (PC-SZ), Gujiao (PC-GJ) and Changzhi (PC-CZ) could reach 601.95, 361.91 and 256.33 m2·g−1, respectively. The diversity in chemical properties of coal with different metamorphic degrees leads to the different properties of porous carbon. PC-SZ had a higher content of oxygen-containing functional groups and defects. The adsorption experiments indicate that PC-SZ had the best adsorption capacity on MB. The adsorption process was fitted by pseudo-second-order model commendably. It was found that more lattice defects and larger interlayer spacing made PC-SZ to become an excellent adsorbent of methylene blue (MB). Therefore, FJH can be an innovative approach for preparing porous carbon with excellent adsorption properties and is expected to achieve large-scale production. [Display omitted] [ABSTRACT FROM AUTHOR]

• P i and P o -induced brushite dissolution exhibited a concentration-dependent manner. • P i precipitated more readily than p o on brushite surfaces. • Outer-spherically adsorbed p o was more labile and mineralizable by phytase. • P o stabilized ACP and delayed its phase transformation to HAP. With the development of agricultural intensification, phosphorus (P) accumulation in croplands and sediments has resulted in the increasingly widespread interaction between inorganic and organic P species, which has been, previously, underestimated or even ignored. We quantified the nanoscale dissolution kinetics of sparingly soluble brushite (CaHPO 4 ·2H 2 O, DCPD) over a broad range of phosphate and/or phytate concentrations by using in situ atomic force microscopy (AFM). Compared to water, we found that low concentrations of phosphate (1–1000 µM) or phytate (1–100 µM) inhibited brushite dissolution by slowing single step retraction. However, with increasing phosphate or phytate concentrations to 10 mM, there was a reverse effect of dissolution promotion at brushite-water interfaces. In situ observations of the coupled dissolution-reprecipitation showed that phosphate precipitated more readily than phytate on brushite surfaces, with the formation of amorphous calcium phosphate (ACP). For a fundamental understanding, zeta potential and in situ Raman spectroscopy (RS) revealed that the concentration-dependent dissolution is attributed to the reverse of outer-sphere to inner-sphere adsorption with increasing phosphate or phytate concentrations. In addition, the mineralization of phytate with outer-sphere adsorption by phytase was higher than that with inner-spere adsorption, and the presence of phytate delayed ACP phase transformation to hydroxylapatite (HAP). These in situ observations and analyses may fill the knowledge gaps of interaction between inorganic and organic P species in P-rich terrestrial and aquatic environments, thereby implicating their biogeochemical cycling and the associated availability. This study revealed a widespread but previously ignored concentration-dependent phosphate or phytate adsorption on mineral-water interfaces and the associated dissolution, precipitation, enzymolysis, and phase transformation, thereby implicating P fates and availability. [Display omitted] [ABSTRACT FROM AUTHOR]