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Abstract The object of this study was to remove the tetracycline (TC) residue in pharmaceutical wastewater after flocculation treatment. MnO 2 /graphene nanocomposite was synthesized by an in situ hydrothermal method and its TC removal rate was up to 99.4%. This nanocomposite had excellent water solubility. More importantly, the introduction of MnO 2 nanorods allowed the avoidance of excessive stacking of treated graphene sheets during the adsorption process, which made the TC molecules to have more opportunities to make contact with the adsorbents. In order to eliminate the interference factors, the adsorption isotherm, kinetics, thermodynamics and mechanism were all studied in TC aqueous solution. The influence of solution pH, contact time, MnO 2 loading amount, temperature and solution concentration on the adsorption process were also assessed. The main adsorption mechanism contributed to the complexation of Mn(IV) and π-π interactions of the benzene ring structure on treated graphene sheets with TC molecules. Graphical abstract Unlabelled Image Highlights • MnO 2 /graphene nanocomposite with highly selective adsorption for TC was prepared. • MnO 2 /graphene nanocomposite has excellent water solubility. • The nanocomposite could effectively remove 99.4% of TC from wastewater. • MnO 2 /graphene can be used for pharmaceutical wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: Cu2+–ZnO/cetylpyridinium–montmorillonite (Cu2+–ZnO/CP–MMT) complexes were prepared using montmorillonite (MMT), Cu2+, Zn2+, and cetylpyridinium (CP). The goal was to assess comparatively the adsorption properties of Cu2+–ZnO/CP–MMT in vitro using pathogenic Escherichia coli. The results showed that Cu2+–ZnO/CP–MMT adsorbed significantly (P <0.05) more E. coli compared with the parent clay. The adsorption process of bacterial cells occurring on the modified MMT surface reached equilibrium after 90min. The percentages of E. coli adsorbed onto the surfaces of Cu2+–ZnO/CP–MMT and MMT in adsorption equilibrium were 84.66% and 47.01%, respectively. Adsorption data from the bacteria-clay systems followed the Langmuir and Freundlich isotherms, but not the BET isotherm. Adsorption of E. coli in acidic medium was higher than in alkaline medium. The extent of bacteria adsorption onto the modified MMT increased with decreasing ionic strength, and with increasing temperature. The processes of E. coli adsorption onto the tested adsorbents were endothermic and spontaneous at the experimental temperature. The mechanism of adsorption of bacteria on Cu2+–ZnO/CP–MMT may involve enhanced hydrophobicity and the reversal of surface charge from negative to positive. [Copyright &y& Elsevier]

Cu2+-exchanged montmorillonite (CEM) was prepared using the method of ion exchange reaction. The goal was to determine the adsorption of methylene blue (MB) onto montmorillonite and CEM. The results showed that treatment with Cu2+ slightly reduced the adsorption of montmorillonite. Temperature, pH value, and ionic strength in the medium had greater or smaller effects on interaction between MB and the clay. The data obtained from MB adsorption onto the tested adsorbents followed the Langmuir and BET equations. Also, the adsorption processes were endothermic and spontaneous in nature. [Copyright &y& Elsevier]

The development of synthetic methods to obtain high value-added mesoporous Al-MCM-41 from a low-cost silicon-aluminum source with low toxicity is an active research topic in solid waste resource utilization. In particular, the controlled synthesis of MCM-41 with a two-level pore distribution is a challenging task. In this work, the synthesis of unimodal and bimodal mesoporous Al-MCM-41s was achieved using acids with different degrees of ionization from coal gasification fine residue (CGFR) as bulk solid waste generated by the coal gasification process. We determined that the degree of acid ionization affected the self-assembly of inorganic/organic species as well as condensation processes, resulting in some changes of the hexagonal mesoscopic structure. The unimodal mesoporous Al-MCM-41 with acetic acid HAc and bimodal mesoporous Al-MCM-41s with an inorganic acid environment (HCl, HNO 3 or H 2 SO 4) could be effectively prepared in a controllable manner by the silicon and aluminum source obtained at alkali dissolution time 6 h and crystallization conditions at pH 10.5 and 383 K in 72 h. Moreover, the synthesis of Al-MCM-41-HAc with different SiO 2 /Al 2 O 3 molar ratios (18–89) could also be realized by different alkali dissolution times. And alkali dissolution time (2–24 h) and the crystallization conditions (pH 4.5–11.5, temperatures 373–393 K, and time 48–96 h) also affected the formation of unimodal and bimodal mesoporous Al-MCM-41-HAc. In addition, the maximum adsorption amount onto bimodal mesoporous Al-MCM-41-H 2 SO 4 (476.19 mg g−1 at 308 K) was larger than that onto unimodal mesoporous Al-MCM-41-HAc (243.90 mg g−1 at 303 K). The mesoporous Al-MCM-41s showed good stability. [Display omitted] • The acid ionizability affected the self-assembly of inorganic/organic species. • The unimodal and bimodal mesoporous Al-MCM-41s were synthesized from CGFR. • The Al-MCM-41-HAc with different SiO 2 /Al 2 O 3 molar ratios could be effectively prepared. • The higher adsorption amounts onto bimodal mesoporous Al-MCM-41-H 2 SO 4 were obtained. [ABSTRACT FROM AUTHOR]

The utilization of coal gasification slag currently has become a central issue in both coal and environmental science. Coal gasification slag has been used as raw materials to synthesize the porous materials. However, for the synthesis of these materials, the high temperature was needed, and not all coal gasification slag could be converted to. This work developed a new strategy to graded synthesis of MCM-41 and carbon/zeolite composite from coal gasification fine residue (CGFR) under mild conditions. By this way, graded preparations of valuable porous materials from CGFR could realize the efficient conversion and utilization of CGFR. The synthesized MCM-41 exhibited highly ordering feature with hexagonal arrays and the straight 1D channels. The MCM-41 zeolite had large surface areas and narrow pore diameter distribution. The different synthesis conditions of MCM-41 from CGFR, such as acidification process, gel pH, crystallization temperature and crystallization time were discussed. As to the synthesized carbon/zeolite composite, it presented a P-type zeolite with the flower-like shape on the substrate of carbon with low degree graphitization. The carbon/zeolite composite had the total specific surface area of 189.27 m2 g−1 and exhibited thermal stability below 300 °C. Meanwhile, the synthesis of carbon/zeolite composite with different alkali dissolution time was also investigated. Besides, the adsorption experiments of toxic crystal violet in water indicated that these two porous materials had potential applications in adsorption and removal of harmful pollutants. • MCM-41 and carbon/zeolite composite were staged synthesized from CGFR. • MCM-41 with large BET of 1013 m2 g−1 exhibited five characteristics diffraction peaks. • The carbon/zeolite composite with BET of 189.27 m2 g−1 had good thermal stability. • MCM-41 and carbon/zeolite composite had good performance for crystal violet remove. [ABSTRACT FROM AUTHOR]

As the bulk of solid waste from coal chemical industry, coal gasification fine slag (CGFS) mainly consists of aluminosilicates and residual carbon. Currently, the common transformation strategy for CGFS entails the preparation of porous materials. However, this method utilizes only a part of the effective components in the slag. Specifically, either the silicon is used to synthesize zeolites, or the porous carbon is obtained through intensified separation. Therefore, it is highly desirable to achieve the simultaneous utilization of silicon and carbon resources in CGFS. In this work, CGFS was used as a low-cost raw material to prepare the P-zeolite/carbon composite in situ. The composite was characterized via XRD, 27Al and 29Si NMR, SEM, FT-IR, and Raman technique. Furthermore, the adsorption removal of crystal violet onto the composite was studied. The adsorption capacity was as high as 625.00 mg g−1, which was much larger than the CGFS and most reported adsorbents. Image 1 • The P-type zeolite/carbon composite was prepared in situ from CGFS. • The composite had flower-shape P-type zeolite and porous lamellar carbon. • The composite had large specific surface area and abundant functional groups. • The adsorption amount of crystal violet onto the composite was up to 625 mg g−1. [ABSTRACT FROM AUTHOR]