High Removal Ability Research Articles

Adsorption of mercury ions from wastewater by a hyperbranched and multi-functionalized dendrimer modified mixed-oxides nanoparticles

In this paper, a novel heterogeneous nanodendrimer with generation of G2.0 was prepared by individual grafting of diethylenetriamine, triazine and l-cysteine methyl ester on the modified aluminum–silicate mixed oxides as a potent adsorbent of Hg(II) ions from aqueous media. The prepared nanodendrimer was characterized by nuclear magnetic resonance spectrum (1H NMR and 13C NMR), Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance UV–Vis spectroscopy (DR UV–Vis), zeta potential (ζ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption experiments at −196°C and elemental analysis. Equilibrium and kinetic models for Hg(II) ions removal were used by investigating the effect of the contact time, adsorbent dosage, initial Hg(II) ions concentrations, effect of solution’s temperature, interfering ions, and initial pH. The contact time to approach equilibrium for higher removal was 6min (3232mgg−1). The removal of Hg(II) ions has been assessed in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Sips isotherms models have also been applied to the equilibrium removal data. The removal kinetics followed the mechanism of the pseudo-second order equation, where the chemical sorption is the rate-limiting step of removal process and not involving mass transfer in solution, which was further proved by several techniques such as zeta potential, FT-IR and DS UV–vis. The thermodynamic parameters (ΔG, ΔH and ΔS) implied that the removal of mercury ions was feasible, spontaneous and chemically exothermic in nature between 15 and 80°C. The nanodendrimer indicated high reusability due to its high removal ability after 15 adsorption–desorption runs. The adsorption mechanisms of Hg(II) ions onto the nanodendrimer was further studied by diverse techniques such as FTIR, EDS, zeta potential, DR UV–Vis spectroscopy and SEM. The possible mechanism of the Hg(II) ions adsorption onto the nanodendrimer could be carried out through the various paths such as electrostatic interaction, complexation, toxic metal chelation and ionic exchange, which eventually resulted in the hydrolysis and precipitation of the adsorbed Hg(II). The l-cysteine methyl ester nanodendrimer could also remove the mercury ions from the Persian Gulf water even after five times of recycling.

Experimental study on catalytic effect of biomass pyrolysis volatile over nickel catalyst supported by waste iron slag

Summary The study aims to analyze catalytic tar destruction, evaluate the activity of the Ni-based catalyst supported by waste iron slag, and obtain clean pyrolysis syngas. The effects of different nickel loadings, catalytic temperatures, and catalyst calcination temperatures on volatile were investigated in order to determine the optimal process condition. The analysis results showed that the iron slag Ni-based catalyst had a relatively low specific surface area. However, it showed an excellent resistance performance to the coke deposition and displayed the high tar removal ability. Moreover, the tar conversion and the yield of syngas were significantly affected by nickel loadings. When the nickel loading reached 3%, the tar dew point was decreased by nearly 100 °C and the tar conversion reached 94.84%. The favorable reaction temperature was about 800 °C based on the consideration of energy consumption and the catalytic performance. Calcination temperature affected tar yield and syngas yield. The application of iron slag in nickel catalyst realized the reutilization of waste materials, indicating significant practical values. Copyright © 2017 John Wiley & Sons, Ltd.

Low-cost synthesis of hollow mesoporous silica spheres and its application in the removal of aromatic volatiles

In the paper, hollow mesoporous silica (HMS) spheres were prepared by an environment-friendly and low-cost method using cheap sodium silicate as silica precursor and inexpensive cationic polystyrene spheres as interior templates. Hollow structure with uniform size were characterized by TEM and SEM images. Nitrogen adsorption-desorption isotherm was used to confirm mesoporous structure with BET surface area of 424m2/g and narrow pore size distribution. TG-IR was utilized to investigate the influence of HMS spheres on the removal of aromatic volatiles. The as-prepared HMS spheres exhibited high removal ability of aromatic volatiles, mainly attributed to interior hollow for facilitating aggregation of aromatic volatiles to smoke particles and external mesoporous for strongly adsorbing aromatic volatiles.

Synthesis of Ca-Al layered double hydroxide from concrete sludge and evaluation of its chromate removal ability

Concrete sludge is an industrial waste slurry containing hydrated cement, aggregates and water. The main components of concrete sludge are CaO, SiO2, Al2O3 and small amounts of metal oxides such as Fe2O3 and MgO. In this study, the calcium component of concrete sludge was used as a raw material for the synthesis of Ca-Al type layered double hydroxide (LDH). The chromate removal ability of the LDH was examined using a potassium chromate solution containing 180mg/L chromate. The LDH showed a high chromate removal ability with a concentration decrease of up to 0.4mg/L. The chromate is removed in the form of CrO42− by anion exchange with NO3− in the Ca-Al NO3 LDH.

MgFe2O4 and MgFe2O4/ZnFe2O4 coated with polyaniline as a magnetically separable photocatalyst for removal of a two dye mixture in aqueous solution

In this work MgFe2O4 and MgFe2O4/ZnFe2O4 coated with polyaniline (PANI) as an efficient magnetically separable photocatalyst were synthesized. The prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, BET analysis, field emission scanning electron microscopy and energy dispersive X-ray analysis. The adsorption and photocatalytic activity of the samples for removal of a two dye mixture of methylene blue and methyl orange in aqueous solution were examined. The results indicate that the MgFe2O4/PANI sample is a promising candidate for effective photodecolorization of both methylene blue and methyl orange dyes in aqueous solution. For the MgFe2O4/ZnFe2O4/PANI sample, a large amount of the removal of the methylene blue via adsorption and photocatalytic experiments was observed. The prepared samples demonstrated the high removal ability after five repeated utilizations. The pseudo-first and pseudo-second order kinetic models were used to describe the adsorption kinetic data. It was observed that the pseudo-second order kinetic model described the adsorption process better than pseudo-first order.

Characterization of potential probiotic lactic acid bacteria isolated from camel milk

The aim of this study was to investigate probiotic characteristics and fermentation profile of selected lactic acid bacteria isolated from raw camel milk. Physiological properties, cell surface properties (hydrophobicity, autoaggregation, co-aggregation), acid and bile tolerance, bile salt hydrolysis, cholesterol removing, exopolysaccharide (EPS) production, hemolytic and antimicrobial activities, resistance toward lysozyme and six antibiotics, and fermentation profile (growth, pH, and proteolysis) were examined. 16S rRNA sequencing was carried out to identify six presumptive LAB isolates. In general, all identified LAB (Lactococcus lactis KX881768, Lactobacillus plantarum KX881772, Lactococcus lactis KX881782 and Lactobacillus plantarum KX881779) showed auto-aggregation ability, high cholesterol removal ability, high co-aggregation, strong antimicrobial activity and EPS production. Among the isolates, Lactococcus lactis KX881768, Lactobacillus plantarum KX881772, Lactococcus lactis KX881782 and Lactobacillus plantarum KX881779 exhibited remarkable cholesterol removal abilities. Similarly, Lactobacillus plantarum KX881779, and Lactococcus lactis KX881782 showed very promising fermentation profiles.

一株好氧反硝化菌的筛选鉴定及其脱氮特性研究

本研究从巴陵石化己内酰胺污水中分离高效好氧反硝化菌，并对菌株的反硝化特性进行研究。通过BTB培养基初筛及菌株硝酸盐的降解实验，从样品中分离得到一株脱氮性能最好的好氧反硝化菌，结合其生理生化特性和16S rDNA测序结果，对菌株进行鉴定。研究不同碳源、C/N、温度及pH对其反硝化能力的影响。筛选得到高效好氧反硝化菌B-5，经鉴定属于假单胞菌属(Pseudomonas sp.)。降解特性研究表明，当碳源为琥珀酸钠或乙酸钠，C/N为15:1，温度为30℃~35℃，pH为6~7时，菌株B-5的降解性能最佳。 This study aimed at the isolation of an aerobic denitrifier with high nitrogen removal ability from caprolactam sewage and its denitrifying characteristics. An aerobic denitrifier with the best deni-trifying performance was isolated from the sample by BTB medium preliminary screening and ni-trate degradation analysis. We used morphological and physiological characteristics as well as its 16S rDNA sequences to identify the strain. Effects of culture conditions, such as carbon sources, C/N ratio, temperature and initial pH, were evaluated regarding denitrifying capacity under aerobic condition. The highly effective strain B-5 was identified as Pseudomonas sp. Studies of degradation characteristics showed that the most efficient nitrate removal rate for B-5 occurred at C/N = 15 when sodium succinate or sodium acetate was supplemented as the carbon source. The optimum temperature for B-5 was 30˚C - 35˚C and optimum pH ranged from 6 to 7.

Superiority of wet-milled over dry-milled superfine powdered activated carbon for adsorptive 2-methylisoborneol removal

Superfine powdered activated carbon (SPAC), which is produced from conventionally sized powdered activated carbon (PAC) by wet milling in a bead mill, has attracted attention for its high adsorptive removal ability in both research and practice. In this study, the performance of dry-milled SPAC was investigated. 2-Methylisoborneol (MIB), an earthy-musty compound commonly targeted by water treatment systems, was used as the target adsorbate. Dry-milled SPAC exhibited lower adsorptive removal of MIB than wet-milled SPAC, even when both SPACs were produced from the same PAC and were composed of particles of the same size. One reason for the lower removal of MIB by the dry-milled SPAC was a higher degree of aggregation in the dry-milled SPAC after production; as a result the apparent particle size of dry-milled SPAC was larger than that of wet-milled SPAC. The dry-milled SPAC was also more negatively charged than the wet-milled SPAC, and, owing to its higher repulsion, it was more amenable to dispersion by ultrasonication. However, even after the dry-milled SPAC was ultrasonicated so that its apparent particle size was similar to or less than that of the wet-milled SPAC, the dry-milled SPAC was still inferior in adsorptive removal to the wet-milled SPAC. Therefore, another reason for the lower adsorptive removal of dry-milled SPAC was its lower equilibrium adsorption capacity due to the oxidation during the milling. The adsorption kinetics by SPACs with different degrees of particle aggregation were successfully simulated by a pore diffusion model and a fractal aggregation model.

Efficient removal of zinc by multi-stress-tolerant yeast Pichia kudriavzevii A16

Heavy metal bioaccumulation by growing microorganisms is a potential technique for treating the heavy metal pollution in food materials, e.g. fishery processing wastes. In this study, a multi-stress-tolerant yeast with high Zn tolerance and efficient Zn removal ability was screened and renamed as Pichia kudriavzevii A16 after identification. High salinity and low pH obviously increased the Zn bioaccumulation capacity of P. kudriavzevii A16, contributing to the increasing Zn removal rate of P. kudriavzevii A16 at 0.5mmol/L Zn from 67.69% to 77.03% and 96.09%, respectively. P. kudriavzevii A16 displayed high specificity of Zn removal at high concentrations of Cu, while high concentrations of Cd significantly inhibited the Zn removal by restraining the yeast growth. P. kudriavzevii A16 possessed more powerful Zn removal ability than Saccharomyces cerevisiae CICC1211 under various environmental stresses. The multi-stress-tolerant P. kudriavzevii A16 can be developed into a potential Zn removal agent using in complex food environments.

オゾンマイクロバブルを用いた高機能洗浄技術

The removal technology of single-wafer processing using ozone is proposed on photoresist removal in the semiconductor manufacturing. Ozone is friendly for the environment and no harm to the product. Before now, the authors indicated that disk-shaped nozzle forms a vortex structure between the disks which is considered to cause the reduction of photoresist removal rate. This study proposes a disk-shaped convex nozzle to suppress the vortex. In order to investigate the effects of the presence or absence of the convex, the removal experiments were conducted. As a result, disk-shaped convex nozzle had the higher removal ability than disk-shaped nozzle in the convex part. Next, as a new removal method, we suggest the ozone microbubble with a Venturi tube. To investigate the performance of the photoresist removal with it, first, the generation of ozone microbubbles is observed in the Venturi tube via a high speed video camera. Next, to clarify the effect of the superficial liquid and gas velocities, the ozone microbubble, and presence or absence of convex, ozone water concentration measurement and photoresist removal experiments were conducted. As a result, the ozone water concentration increased with increasing superficial velocity and the remaining photoresist thickness reduced. Also, ozone microbubble had the higher removal ability than ozone water single-phase. Compared presence and absence of convex, convex influenced photoresist removal efficiently. In addition, compared with the existing study, it is suggested that the superficial liquid and gas velocities and ozone water concentration affect the photoresist removal rate.

One Pot Method to Synthesize a Novel La–Zr Composite with Exceptionally High Fluoride Removal Performance

A novel La–Zr composite was prepared by one pot method in mild conditions, and it shows a high fluoride removal ability of 143 mg/g. The powders were characterized by SEM, EDS, and FTIR. The effects of various factors such as pH, the presence of coexisting anions, contacting time, and initial fluoride concentration were investigated. The equilibrium data were studied by being fitted to several isotherm models, and the kinetic data are found to be described very well by the pseudo-second-order kinetic model. The overall rate of fluoride adsorption is likely to be controlled by chemisorption processes. The mechanism of adsorption was discussed in detail.

ChemInform Abstract: Synthesis and Use of Bimetals and Bimetal Oxides in Contaminants Removal from Water: A Review

AbstractReview: 183 refs.

Biosorption of Congo Red from aqueous solution onto burned root of Eichhornia crassipes biomass

Biosorption is becoming a promising alternative to replace or supplement the present dye removal processes from dye containing waste water. In this work, adsorption of Congo Red (CR) from aqueous solution on burned root of Eichhornia crassipes (BREC) biomass was investigated. A series of batch experiments were performed utilizing BREC biomass to remove CR dye from aqueous systems. Under optimized batch conditions, the BREC could remove up to 94.35 % of CR from waste water. The effects of operating parameters such as initial concentration, pH, adsorbent dose and contact time on the adsorption of CR were analyzed using response surface methodology. The proposed quadratic model for central composite design fitted very well to the experimental data. Response surface plots were used to determine the interaction effects of main factors and optimum conditions of the process. The optimum adsorption conditions were found to be initial CR concentration = 5 mg/L−1, pH = 7, adsorbent dose = 0.125 g and contact time = 45 min. The experimental isotherms data were analyzed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherm equations and the results indicated that the Freundlich isotherm showed a better fit for CR adsorption. Thermodynamic parameters were calculated from Van’t Hoff plot, confirming that the adsorption process was spontaneous and exothermic. The high CR adsorptive removal ability and regeneration efficiency of this adsorbent suggest its applicability in industrial/household systems and data generated would help in further upscaling of the adsorption process.

Photodegradation of phenol via C3N4-agar hybrid hydrogel 3D photocatalysts with free separation

The agar-C3N4 hybrid hydrogel photocatalysts with 3 dimension (3D) network structure have been prepared via thermoreversible phase transition of agar. The hybrid hydrogels show high efficient pollutants removal ability by synergistic effect of adsorption and photocatalytic degradation. The removal ability of phenol and methylene blue (MB) by hybrid hydrogel is about 1.3 and 4.5 times of pure g-C3N4 respectively. The pollution can be degraded continuously via agar-C3N4 hybrid hydrogels photocatalysts without separation.

Self-cleaning ability of titanium dioxide clear paint coated architectural mortar and its potential in field application

The self-cleaning property of building materials is a much desirable function. It not only improves the aesthetic appearance of the building, but also effectively reduces the costs of routine maintenance. Normally, titanium dioxide (TiO2) incorporated cementitious materials display multiple photocatalytic functions, including the self-cleaning ability. However, attaining a photocatalytic functional building product with both a high photocatalytic efficiency and a robust weathering resistant ability still remains challenging. This study investigated the strategy of directly applying a TiO2 containing paint (clear in colour) on the surface of self-compacting architectural mortars (SCAM). Its self-cleaning (in terms of rhodamine b (RhB) degradation) and weathering resistant ability (accelerated façade weathering) were evaluated under both Ultraviolet-A (UV-A) and visible light irradiation. For comparison, 5% P25-TiO2-intermixed and dip-coated SCAM samples were also prepared and tested. The results showed that the TiO2 paint coated SCAM sample displayed both a high photocatalytic RhB removal ability and a robust weathering resistance under all conditions. In contrast, the 5% P25-TiO2-intermixed samples only achieved a significantly lower RhB removal efficiency. Although the P25-TiO2-coated SCAM delivered a satisfactory self-cleaning performance, it suffered a significant loss in the RhB abatement after subjecting to the façade weathering process. The overall results suggest that the TiO2 coated SCAM has the potential to be used as a resource and energy efficient product for air-purifying and self-cleaning applications.

Versatile photocatalytic functions of self-compacting architectural glass mortars and their inter-relationship

Interests in the combined use of titanium dioxide (TiO2) photocatalyts with cementitious materials to produce functional cement based photocatalytic products (PCP) have attracted increasing research attention. However, an effective method to obtain a high photocatalytic efficiency, thus multiple photocatalytic functions, is in strong demand. This study investigated the strategy of directly applying a TiO2 containing paint on the surface of self-compacting architectural mortars (SCAM). For comparison, 5% TiO2-intermixed SCAM samples were also prepared. The results showed that the TiO2 coated SCAM sample displayed a high photocatalytic NOx and xylene removal ability under UV-A and Sunlight irradiation conditions. In contrast, 5% TiO2-intermixed samples only achieved a significantly lower NOx removal efficiency, and failed to degrade xylene. In addition, the TiO2 coating on the SCAM surface also demonstrated a high rhodamine B (RhB) degradation ability. Moreover, a total inactivation of Escherichia coli was observed after 120min UVA irradiation for the TiO2 coated SCAM. Whereas, the 5% TiO2-intermixed SCAM only exhibited a negligible E. coli killing activity. All the architectural mortar samples were found to have a low bioreceptivity. Overall, the TiO2 coated SCAM has the potential to be used as environmentally-friendly products for air-purifying, bactericidal and self-cleaning applications.

Efficient removal of fluoride by hierarchical MgO microspheres: Performance and mechanism study

Hierarchical MgO microspheres assembled by numerous porous nanoplates were successfully obtained by annealing the precursors of magnesium carbonate hydroxide hydrate synthesized through a facile and cost-effective hydrothermal process at low temperature. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller measurements. The fluoride removal performance of the hierarchical MgO microspheres was investigated. The adsorption isotherm could be well fitted in Freundlich model, and the adsorption capacity was over 115.5mg/g at pH 7. The absorbent also showed high fluoride removal ability in a wide pH range of 2–10, which is favorable for practical application. The effect of co-existing anions on fluoride removal was also investigated. The result indicated that the fluoride adsorption capacity was influenced when carbonate, bicarbonate and phosphate existed above the concentration of 50mg/g. In addition, the adsorption mechanism was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A novel hydroxyl and carbonate co-exchange mechanism has been proposed for the first time. It can be found that fluoride ions could replace the surface carbonates which formed by the reaction of MgO and the adsorbed CO2 molecules, and then anchored on the MgO surface.

Removal of Gaseous Elemental Mercury by Cylindrical Activated Coke Loaded with CoOx-CeO2 from Simulated Coal Combustion Flue Gas

Co–Ce mixed oxides were loaded on commercial cylindrical activated coke granules (CoCe/AC) by an impregnation method to remove gaseous elemental mercury (Hg0) from simulated coal combustion flue gas at low temperature (110–230 °C). Effects of the Co/Ce molar ratio in Co–Ce mixed oxides, mixed oxides loading value, reaction temperature, and flue gas components (O2, NO, SO2, H2O) on Hg0 removal efficiency were investigated, respectively. Brunauer–Emmett–Teller analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) analysis were employed to analyze the characteristics of the samples. Results showed that up to 92.5% of Hg0 removal efficiency could be obtained over Co4.5Ce6/AC at 170 °C. The remarkably high Hg0 removal ability of Co4.5Ce6/AC mainly depended on the synergetic effect between cobalt oxide and ceria. Additionally, different with the pure N2 condition, the existence of O2 and NO...

Probiotic properties of Enterococcus strains isolated from traditional naturally fermented cream in China.

SummaryThe purpose of this study was to evaluate the probiotic properties of Enterococcus strains isolated from traditional naturally fermented cream in China. Four E nterococcus isolates showed high cholesterol removal ability in media were identified as E nterococcus durans (KLDS 6.0930 and 6.0933) and E nterococcus faecalis (KLDS 6.0934 and 6.0935) by 16S rRNA and pheS gene sequences, respectively, and selected for further evaluation. In order to assess the probiotic potential and safety of these strains, the property of four E nterococcus strains were examined, including acid and bile tolerance, adherence to Caco‐2 cells and antibiotics susceptibility. All four strains showed potential cholesterol assimilation, de‐conjugation of bile salts and/or cholesterol degradation to remove cholesterol in vitro. In addition, the potential effect of E. durans KLDS 6.0930 on serum cholesterol levels was evaluated in Sprague‐Dawley rats. After 4 weeks administration, compared with rats fed a high‐cholesterol diet without lactic acid bacteria supplementation, there was a significant (P < 0.05) decrease in the total cholesterol and low‐density lipoprotein cholesterol levels in the serum of rats treated with KLDS 6.0930. Furthermore, total bile acid level in the feces was significantly (P < 0.05) increased after KLDS 6.0930 administration. These observations suggested that the strain E. durans KLDS 6.0930 may be used in the future as a good candidate for lowering human serum cholesterol levels.

Nanoscale zero-valent iron particles supported on reduced graphene oxides by using a plasma technique and their application for removal of heavy-metal ions.

Nanoscale zero-valent iron particles supported on reduced graphene oxides (NZVI/rGOs) from spent graphene oxide (GO)-bound iron ions were developed by using a hydrogen/argon plasma reduction method to improve the reactivity and stability of NZVI. The NZVI/rGOs exhibited excellent water treatment performance with excellent removal capacities of 187.16 and 396.37 mg g(-1) for chromium and lead, respectively. Moreover, the NZVI/rGOs could be regenerated by plasma treatment and maintained high removal ability after four cycles. X-ray photoelectron spectroscopy analysis results implied that the removal mechanisms could be attributed to adsorption/precipitation, reduction, or both. Such multiple removal mechanisms by the NZVI/rGOs were attributed to the reduction ability of the NZVI particles and the role of dispersing and stabilizing abilities of the rGOs. The results indicated that the NZVI/rGOs prepared by a hydrogen/argon plasma reduction method might be an effective composite for heavy-metal-ion removal.