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Thehydrophobic property and structure of Na-bentonite (Na-bent)were tuned by intercalation with cationic surfactants for lipase adsorption.The adsorption isotherms of lipase on Na-bent and modified bentonitesdemonstrated Langmuir-type shape, and Na-bent showed higher adsorptionefficiency than modified bentonites. The observed overlap of lipasemolecules on the support and the interactions between these moleculesunder high protein loading caused the reduction in the activity ofimmobilized lipase. The immobilized lipases on modified bentonites(Bent-DTAB-lipase, Bent-CTAB-lipase, and Bent-OTAB-lipase) exhibitedhigher catalytic activity than that on Na-bent, due to the hydrophobicallyinterfacial activation of modified bentonites toward lipase. The highestcatalytic activity and stability were observed on Bent-CTAB-lipase,resulting from the tunable hydrophilic/hydrophobic balance of thesupport’s surface, while the excessive hydrophobic propertyshowed negative influence on lipase’s catalytic performance.The immobilized lipases onto modified bentonites with hydrophobicproperty showed higher thermal stability and reusability than Na-bent-lipase. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a novel combination of pillared bentonite (OH-Al-bent) with zero valent iron (ZVI) was studied in column experiments so as to enhance Cr(VI) removal efficiency and improve the longevity of Fe0-based permeable reactive barriers. The influence of mixing manner, bentonite type, initial pH and OH-Al-bent amount on the removal efficiency were evaluated. The enhanced removal was attributed to the synergetic effect between adsorption by OH-Al-bent and reduction by ZVI. The adsorption facilitated the mass transfer of Cr(VI) from aqueous to iron surface, and thus accelerated the reduction of Cr(VI) by ZVI. Additionally, the higher removal efficiency was observed under lower pH, and the complete Cr(VI) removal could last longer due to the buffering effect of OH-Al-bent. XPS analysis indicated that Cr(VI) was reduced to Cr(III), and then precipitated in the forms of Cr(III) and Fe(III) hydroxides or Cr(III)–Fe(III) hydroxides. But fewer precipitations on iron surface were detected when OH-Al-bent was combined with ZVI, which might also contribute to the extended longevity of reaction medium. [Copyright &y& Elsevier]

Abstract: The nanoscale zero valent iron supported on pillared clay (NZVI/PILC) was prepared, and used for nitrate removal with the objective of enhanced efficiency. The composite NZVI/PILC was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). Good dispersion of NZVI particles (ca. 30–70nm) in the clay phase was observed. The removal efficiency of nitrate by this composite was investigated, and compared with commercial iron powder and NZVI containing the same amount of iron. Results showed nitrate could be completely removed by NZVI/PILC within 120min. This efficiency was not only much higher than that (62.3%) by NZVI alone, but also superior to the sum (71.5%) of reduction by NZVI plus adsorption (9.19%) by PILC. The kinetic studies indicated that the rate of nitrate removal was positively related to the adsorption. So we suggested that the adsorption of nitrate by PILC enhanced the mass transfer of nitrate from solution to iron surface, therefore accelerated the reduction rate. The end-products of nitrate reduction by NZVI/PILC were identified as ammonium and nitrogen gas, implying NZVI/PILC may help cut down the total nitrogen amount in water. [Copyright &y& Elsevier]

Abstract: The organobentonite (CTMA-Bent) was prepared from Na+-saturated bentonite (Na-Bent) by intercalation with cetyltrimethylammonium bromide (CTMA), and used as a carrier of nanoscale zero valent iron (NZVI) for the removal of atrazine. The NZVI/CTMA-Bent composite was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM), and good dispersion of nanoscale iron particles on the carrier was observed. The removal efficiency of atrazine by this composite was compared with that by commercial iron powder and NZVI itself. For both treatments by NZVI and NZVI/CTMA-Bent, the removal efficiency increased as the pH of the solution decreased, and the removal percentage of atrazine by NZVI/CTMA-Bent reached 63.5% at initial pH=5.0 after 120min. It is not only much higher than that (26.6%) by NZVI containing the same amount of iron, but also superior to the sum (32.1%) of reduction by NZVI plus adsorption by CTMA-Bent (5.5%). Besides, the NZVI/CTMA-Bent has a good long-term stability, and the carrier CTMA-Bent could prevent the iron ions (the byproduct of dechlorination) from leaching into the solution. [ABSTRACT FROM AUTHOR]

Abstract: Inorganic–organic bentonites were prepared by co-adsorption of cetyl trimethylammonium (CTMA) ions onto bentonites intercalated by poly(hydroxo aluminum) or poly(hydroxo iron) cations. The inorganic–organic bentonites adsorbed much more anionic herbicide 2,4-D than the inorganic and organic bentonites. For bentonites modified with poly(hydroxo iron) and CTMA ions, the enhancement may be attributed not only to the van der Waals interaction between 2,4-D and the organic cations, but also to the strong bonding of 2,4-D on the inorganic cations, which was confirmed by desorption studies, XRD measurements and FTIR analysis. The inorganic–organic bentonites did not show higher adsorption of acetochlor compared to the organo-bentonite. For such a nonionic herbicide, the van der Waals interaction dominated the adsorption, and the inorganic modification did not make an obvious contribution to the adsorption. [Copyright &y& Elsevier]

The discharge of untreated colored wastewater poses a severe threat to global health. This work reports a simple yet highly efficient way to modify Zhundong coal (MZD) with hydroxyl functional groups for malachite green (MG) removal. The modification significantly improved the adsorption capacity of MG from 63.0 mg/g to 538.7 mg/g. According to Fourier transform infrared spectroscopy, zeta-potential analyzer, X-ray photoelectron spectroscopy, and N 2 absorption characterization, the improvement in adsorption capacity was mainly attributed to the enhancement of hydroxyl functional groups on the surface of coal. The adsorption of MG on MZD depended on pH, and the highest removal efficiency reached 99.7% at pH 10 with an initial MG concentration of 500 mg/L. The adsorption process was mainly controlled by chemisorption, and it was endothermic and spontaneous according to thermodynamic analysis. The adsorption data could be well reproduced by the pseudo-second order kinetic model and the Redlich-Peterson isotherm model. The MZD shows good regeneration performance with only a 16.9% reduction of initial adsorption capacity after five circles. Hydrophobic interactions, π-π interactions, and pore-filling contributed to adsorption, whereas electrostatic interactions played a dominant role in the MG removal by MZD. This work provides a new sight to prepare useful and cheap adsorbents from coal to remove contaminants from printing and dyeing wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Organobentonites were prepared from Na-bentonite (NB) by intercalation with cetyltrimethyl ammonium bromide (CTMAB), and used to support the lipase from porcine pancreas. The immobilized lipase showed higher activity in hydrolysis of olive oil than free lipase, with the highest specific activity of 347.8Ug−1 protein for lipase immobilized on bentonite-CTMAB100 (BC100-lipase). The apparent activation energy (E a) of catalysis declined from 29.25kJmol−1 for free lipase to 16.31kJmol−1 for BC100-lipase, resulting in a higher catalytic efficiency of lipase. The improvement of catalytic activity was attributed to the interfacial activation by hydrophobic microenvironment and highly scattered surface created by organobentonite, according to the structural and morphological characterizations by Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). The immobilized lipase showed better resistance to pH and heating inactivation in comparison to the free lipase. After the storage of 8 days, BC100-lipase retained 80.7% of initial activity, which was 2.7 times higher than the residual activity of free lipase. Particularly, BC100-lipase kept 82.5% of initial activity after 6 continuous recycles under vigorous agitation, showing the excellent stability of the immobilized lipase by adsorption. [Copyright &y& Elsevier]

The treatment of hazardous LCD is a complicated coupled process, which contains a large number of impurity metals, especially Fe(III), increased the difficulty of In(III) recovery. Moreover, the defects of the traditional extraction process, such as extractant ageing quickly, difficulty to back-extraction, and easy emulsification, seriously restricted the efficient and environmentally friendly recovery of In. Therefore, a novel adsorbent (D2EHPA/SiO 2 –P) was synthesized for the separation and recovery of In(III), and a new recovery process was developed to eliminate the defects of traditional In recovery process in this study. D2EHPA/SiO 2 –P exhibited excellent adsorption selectivity and kinetics for In(III), and the adsorption equilibrium was obtained within 3 min. The adsorption process of In(III) conformed to the pseudo-second-order and Langmuir model. In(III) on D2EHPA/SiO 2 –P was desorbed by 3 M HCl solution, and D2EHPA/SiO 2 –P still had high adsorption and desorption efficiency for In(III) after 5 times of adsorption-desorption cycle experiments. The adsorption mechanism study found that the O–H bond on the D2EHPA participated in the substitution reaction and bonded with In(III) as the adsorption site during the adsorption process. The bond order value of In–O bond was the lowest in the D2EHPA adsorbed In(III) during the desorption process, indicating that In–O bond was easy to break and desorption form D2EHPA. Finally, in the 0.1M H 2 SO 4 system, a new process of using H 2 C 2 O 4 to reduce Fe(III) in advance, and then using D2EHPA/SiO 2 –P to adsorb In(III) was designed to recover In(III) without producing toxic gas, which realized the separation of In(III) and Fe(III). Our findings showed that the developed recovery process was both efficient and environmentally friendly, which had the potential for industrial application of In recovery from hazardous LCD. [Display omitted] • A silica-based adsorbent was successfully synthesized to separate and recover In(III). • A new process was designed to recover In(III) without producing toxic gas. • D2EHPA/SiO 2 –P showed excellent adsorption selectivity and kinetics towards In(III). • Adsorbent had good desorption and reusability proved by 5 adsorption-desorption cycles. • O–H bond in D2EHPA was involved in the binding and substitution reaction of In(III). [ABSTRACT FROM AUTHOR]

Abstract The porous biochar was prepared by pyrolysis of wood at 600–800 °C in the air-containing atmosphere, so as to enhance the biochar's capacity for adsorption of antibiotics from water. The analytical results obtained from N 2 adsorption/desorption indicated that air addition in pyrolysis atmosphere improved significantly the biochar's porosity, especially the development of mesopores. The mesoporous biochars showed high adsorption of antibiotics, and the highest adsorption was observed on the A 1/5 C800 biochar prepared at the air/gas ratio of 1/5 and heat treatment temperature (HTT) of 800 °C. The adsorption isotherm data were well fitted to the Langmuir model, and the maximum adsorptions (Q m) of tetracycline and sulfadiazine on the A 1/5 C800 sample are 163 and 261 mg/g respectively, which are 18.8 and 52.8 folds of those on the microporous NC800 biochar prepared at the same HTT but in total nitrogen atmosphere. The outstanding performance of mesoporous biochar was linked to the utilization of more inner pore surface for adsorption, which favors the adsorption of smaller-sized sulfadiazine molecules. While the stronger interactions between tetracycline and biochar contributed to the relatively higher adsorption of tetracycline on the microporous biochar. The mesoporous biochar retained most of the adsorption capacity (>50%) in a wide pH range (3.5–10) and with the co-existence of humic acid (10 mg/L). In general, this research provides a simple and green method to enhance the biochar's efficiency as an adsorbent for remediation of water contaminated by antibiotics. Graphical abstract Unlabelled Image Highlights • Addition of air in pyrolysis atmosphere enhanced the biochar's mesoporosity. • The mesoporous biochars showed high adsorption of antibiotics from water. • The adsorption is related to the molecular size of antibiotics and their interactions with biochar. • Influences of pH and co-existing humic acid on adsorption were evaluated. • A clean and facile method for improving biochar's adsorption capacity is proposed. [ABSTRACT FROM AUTHOR]

Nanoscale zero valent iron (NZVI) can remove Ni(II) from wastewater through surface adsorption and then reduction into lower-toxic Ni 0 , but the reduction is often blocked by the iron oxide shell of NZVI. In this study, the negatively charged Na-saturated bentonite (Na-bent) with high adsorption capacity to Ni(II) was used to support NZVI for improving the removal and reduction of Ni(II), and the functions of Na-bent were investigated by X-ray photoelectron micro-spectroscopy (XPS), transmission electron microscope (TEM) and Fe(II) determination. The results showed that Na-bent as a carrier could enrich Ni(II) on the reaction surface, protect the surface of NZVI from oxidation, prevent the aggregation of NZVI particles, and decrease the iron oxides products on NZVI surface by pH buffering. Therefore, NZVI/Na-bent not only showed much higher removal efficiency of Ni(II) (98.5%) than the sum (48.8%) of those by bare NZVI removal (41.9%) and by Na-bent adsorption (6.9%), but also greatly enhanced the reduction efficiency of Ni(II) into Ni 0 by facilitating the electron transfer from Fe 0 core to the surface-adsorbed Ni(II). In general, the unique property of bentonites will provide effective solutions to support NZVI for enhancing the removal and transformation of various environmental contaminants. [ABSTRACT FROM AUTHOR]