Scanning Electron Microscope-energy Dispersive Spectrometer Research Articles

Microbiologically induced concrete corrosion in the cracked sewer pipe under sustained load

Microbiologically induced concrete corrosion (MICC) and stress crack are the most common structural defects in concrete sewer pipes. To investigate the microbial corrosion behavior of cracked concrete pipes under sustained loading, coupons with no load, 100% D-Load, and 120% D-Load were pre-adjusted to a suitable environment for acidophilic sulfur oxidizing bacteria (ASOB) colonization, and then placed together in a microbial chamber for 90-day accelerated corrosion. The corrosion variances of these coupons were compared in terms of surface morphology, crystalline violet staining, pH evolutions, crack width changes, as well as characterization results including Scanning Electron Microscope- Energy Dispersive Spectrometer (SEM-EDS) and X-ray Diffraction (XRD). It was found that the stress level slightly accelerates the pH drop on the coupon surface, positively correlates with the corrosion product content of the semi-corrosive layer, and causes stress-corrosion cracking of the semi-corrosive layer, but has little effect on corrosion loss. Stress-corrosion effects were only found in the semi-deteriorated layer of the stressed coupon, but no significant acceleration effect on corrosion rate was observed. This is explained by the fact that MICC is a non-diffusive corrosion where the semi-deteriorated layer is rather thin. Thus, cracking or not of the semi-deteriorated layer does not affect the corrosion rate. This study improves understanding of the service deterioration of sewage pipes.

The establishment of Boron nitride@sodium alginate foam/polyethyleneglycol composite phase change materials with high thermal conductivity, shape stability, and reusability

Adopting organic phase change materials (PCMs) for the management of electronic devices is restricted by low thermal conductivity. In this paper, the composite PCMs are established by freeze-drying and vacuum impregnation. Herein, polyethylene glycol (PEG) is induced as heat storage materials, Boron nitride (BN) is embedded as filler stacking in an orderly fashion on the foam walls to improve thermal conductivity and sodium alginate (SA) is formed as supporting material to keep the shape of the composite stable. X-ray diffractometry, scanning electron microscopy-energy dispersive spectrometer, thermal gravimetric analysis, thermal conductivity meter, differential scanning calorimeter, and Fourier transform infrared were used to characterize the samples and thermal cycles were employed to measure the shape stability. The results exhibit the BN@SA/PEG composite PCMs have good chemical compatibility, stable morphology, and thermal stability. Due to the high porosity of foam, PEG endows the composite PCMs with high latent heat (149.11 and 141.59 J∙g –1 ). Simultaneously, BN@SA/PEG shows an excellent heat performance with high thermal conductivity (0.99 W∙m –1 ∙K –1 ), reusability, and shape stability, contributing the composite PCMs to application in the energy storage field. This study provides a strategy to manufacture flexible, long-serving, and shape-stable PCMs via introducing BN@SA foam as a storage framework, and these PCMs have great potential in thermal management in the electronic field.

Influencing Mechanism of Titanium-Extracted Tailing Slag on the Strength of CaO Steel Slag Hardened Paste.

Hardened pastes with different mass percentages of steel slag (SS)/titanium-extracted tailing slag (TETS) were prepared under fixed CaO content to determine the influencing mechanism of TETS on the strength of CaO SS hardened paste. Furthermore, the effects and laws of curing time and SS/TETS ratios on the strength of hardened pastes were also investigated in this study. Importantly, hydration products, microstructures and the micro-area compositions of hardened pastes were analysed using X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy-energy dispersive spectrometer, respectively, to reveal the influencing mechanism of TETS on the CaO SS hardened pastes. The results demonstrated that the early strength of hardened pastes increases considerably following the inclusion of TETS. Specifically, the strength of the sample with an SS/TETS ratio of 22.5:67.5 at 1 d can be increased by more than 14 times. Notably, its strength at 90 days reached 19.36 MPa. Moreover, the diffraction peaks of calcite and C-S-H in the samples were also strengthened. Meanwhile, a diffraction peak of hydrocalumite appeared, and the calcites in the samples were curled up. When the SS/TETS ratio was equal to or more than 45:45, a diffraction peak of Ca(OH)2 appeared in the sample. Only a diffraction peak of Ca(OH)2 and weak diffraction peaks of calcite and C-S-H were observed in the samples without TETS, but there was no diffraction peak of hydrocalumite. The strength at 90 days was only 4.92 MPa. The increased strength of the hardened paste is closely related to the production of new phases after adding TETS. Solid particles in the hardened paste are cemented into a whole because of the hydration of C-S-H. Calcite forms the skeleton of the hardened pastes, whereas hydrocalumite fills in the pores among particles in hardened pastes, thus making them more compacted. As a result, there is increased.

Study of novel Ti/nanoTiO2-CuO electrode preparation for electrocatalytic degradation of drug pollutant from aqueous solution

The main aim of this study is to prepare a novel electrode through the Ti/nanoTiO2 electrode modification by the introduction of CuO nanoparticles using the electrophoretic deposition (EPD) technique. Field emission scanning electron microscope-energy dispersive spectrometer (FESEM-EDX), X-ray diffraction (XRD), linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chrono-potentiometry (CP), and chrono-amperometry (CA) analyses were used to characterize the surface and electrochemical properties of the Ti/nanoTiO2-CuO electrode, respectively. According to the performed analyses, superior results were seen which confirmed the improved charge transfer rate, electrical conductivity, stability, and electro-catalytic activity of the novel Ti/nanoTiO2-CuO electrode. Electrochemical removal of the Ciprofloxacin (CIP) as a model pollutant was carried out to evaluate the electro-catalytic performance of the novel prepared electrode. Furthermore, the important operational parameters in the electrochemical removal process including pH, current, reaction time, and electrolyte concentration were modeled and optimized by central composite design. Under the optimal conditions, the maximum CIP removal and chemical oxygen demand (COD) efficiencies were 85.91% and 81.25%, respectively. The reusability test indicated that the prepared electrode had relatively good stability. Ultimately, according to the results, the Ti/nanoTiO2-CuO electrode can be employed as a promising anode in the electro-catalytic removal of drug pollutants.

Biodegradation of organic compounds in the coal gangue by Bacillus sp. into humic acid.

Coal gangue (CG), one of the world's largest industrial solid wastes produced during coal mining, is extremely difficult to be used owing to its combined contents of clay minerals and organic macromolecules. This study explored a novel process of degrading the harmful organic compounds in the CG into humic acid using a biological method characterized by scanning electron microscope-energy dispersive spectrometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analyzer. The results reveal that adding selected Bacillus sp. to the CG for 40 days can increase the humic acid content by ~ 17 times, reaching 17338.17mg/kg, which is also the best level for promoting plant growth. FTIR and XPS spectra show that the organic compounds in the CG transforms primarily from C=C to C=O, COOH, and O-H groups, indicating that the organic compounds are gradually oxidized and activated, improving the humic acid concentration of soil. In addition, Bacillus sp. decreases pH and benzo[a]pyrene contents, and increases the content of available nutrients. After microbial degradation, coal gangue can be turned into ecological restoration materials.

Preparation, characterization, antioxidant and antianemia activities of Poria cocos polysaccharide iron (III) complex

As a new natural antioxidant with high safety and non-toxic side effects, polysaccharide can also be used as a critical macromolecular carrier to form a stable iron complex with Fe3+. Our previous study has extracted and purified the homogeneous polysaccharide (PCP1C) from Poria cocos. In this study, the PCP1C-iron (III) complex was synthesized by co-thermal synthesis with PCP1C and ferric trichloride. The chelating capacity, iron releasing capacity, and qualitative identification of complex were evaluated. The complex was characterized by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) analysis, particle size distribution, and fourier transform infrared (FTIR) spectroscopy. The antioxidant and iron supplement effects of the complex were also studied in vitro and in the iron deficiency anemia (IDA) rat model. The results showed that the iron content in the PCP1C-iron (III) complex was 28.14% with no free iron, and the iron release rate was 95.3%. The structure analysis showed that the iron core of the PCP1C-iron (III) complex existed in the form of β-FeOOH and the surface of the complex become smooth and particle size increased, which indicated the high iron content of polysaccharide iron and slow release. Furthermore, we found that the PCP1C iron (III) complex had positive scavenging effect on DPPH, ABTS, MDA, and hydroxyl radical in vitro study and significantly increased the levels of red blood cell (RBC), Hemoglobin (Hb), and red blood cell specific volume (HCT) in IDA rat model. Therefore, our results suggested that the PCP1C-iron (III) complex is expected to develop into a new comprehensive iron supplement and antioxidant.

Green and efficient recovery of stainless steel dust by iron-bath direct reduction

In this study, valuable Cr and Fe in stainless steel dust (SSD) were extracted and then recycled for industrial production. The basic laboratory experiments on the direct reduction of SSD by molten iron were conducted to study the reduction mechanism of Cr2O3 during the recovery of SSD in the iron bath process. A reaction model was established to investigate the variation in material transport in the boundary layer during the reduction of Cr2O3. The phase components, micromorphology, and chemical composition of the experimental raw materials and samples were analyzed by X-ray diffraction, scanning electron microscope–energy dispersive spectrometer, inductively coupled plasma–mass spectrometry, and carbon–sulfur analyzer. The experimental results showed that Cr2O3 and FeO combined in SSD could be reduced by C in molten iron, and that the reduction of FeO occurred before that of Cr2O3. The C and Cr contents in molten iron varied with experimental time in parabolic and cubic polynomial forms, respectively. At 1823 K, the reduction ratios of Cr2O3 and FeO after 35 min reached their highest values of 73.03 % and 90.76 %, respectively. Based on theoretical and experimental analyses, a recovery process was developed to recycle the dust generated during stainless steel smelting for its own production. This process can continuously absorb SSD without any complex equipment and is expected to completely mitigate the environmental impact caused by the presence of SSD.

Study on Mix Proportion Optimization and Microstructure of Coal-Based Solid Waste (CSW) Backfill Material Based on Multi-Objective Decision-Making Model.

The preparation of underground-backfill material from CSW can be used for large-scale disposal of solid waste. The proportion of backfill material plays an important role in transportation and backfilling effect, and the mix-proportion optimization of backfill material is essentially a multi-factor and multi-objective optimization problem. In this paper, to obtain the mix proportion of backfill materials with optimal comprehensive-evaluation indexes, and suitable for the engineering application, the fluidity and strength of backfill material, mainly composed of coal gangue(CG), fly ash (FA), flue gas desulfurization gypsum (FGD gypsum), and gasification coarse slag (GCS), were tested by single-factor transformation method, and the effects of various solid wastes on the slump-flow, bleeding rate and early strength of backfill material were analyzed. The optimal mix proportion of CSW with the slump-flow, bleeding rate, and 3-day and 7-day strengths as the evaluation indicators is FA: GCS: FGD gypsum: CG = 25%:25%:25%:25%, according to the multi-objective decision model. Furthermore, the comprehensive evaluation index that meets the requirements of mine backfilling is obtained by changing the ordinary portland cement (OPC) content, that is, the optimal OPC content is 10% of the total solid waste, and the mass concentration is 78%. Finally, the pore structure, micromorphology, and composition of the backfill material with the optimal mix proportion were studied by Mercury Intrusion Porosimetry (MIP), X-ray Diffraction (XRD), and Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS). The research results provide a good reference for the field application of CSW for underground backfilling.

Evaluation of Pozzolanic and Alkali-Activated Reactivity of Low-Purity Calcium Bentonite.

Alkali-activated cement (AAC) is a sustainable building material with low carbon emissions, but it has a growing demand for raw materials. In this study, the potential of low-purity modified calcium bentonite (CB) as a raw material for AAC was evaluated. The thermodynamic changes and pozzolanic properties of calcined CB were determined using X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), zeta potential, and a strength activity index (SAI) test. The compressive strength test, scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), and Fourier-transform infrared (FTIR) spectroscopy were performed to examine the compatibility between CB and AAC. It was revealed that CB is a low-purity clay with low-pozzolanic activity. Calcination enhanced its pozzolanic activity, and the optimum temperature is 750 °C. The incorporation of modified CB improved the mechanical properties of AAC, and low-temperature modified CB had better compatibility with AAC than the high-temperature modified CB. Calcination at 150 °C had little effect on the structure of CB, and the water absorption of montmorillonite increased the ion concentration, increasing the rate and degree of hydration. Furthermore, low-temperature calcination had a dissolution-precipitation effect, resulting in leaf-like CaO·SiO2·H2O (C-S-H) gels, whereas the high-temperature calcination of CB was very reactive, resulting in flower-like C(N)-S-H gels.

Highly remediation capacity of tetracycline by iron‑manganese bimetallic materials: Performance and mechanisms

To enhance the decontamination capacity of zero-valent iron and mitigate its susceptibility to oxidation and passivation, manganese (Mn) was introduced in the current study to prepare the iron‑manganese bimetallic material by one-step chemical reduction method to remove tetracycline (TC). A series of methods including Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM) and X-ray Photoelectron Spectroscopy (XPS) were applied to investigate the characteristics of the nanocomposite. Furthermore, batch experiments were conducted to explore the effects of key parameters such as dosage, pH, initial concentration and coexisting ions on the removing TC with Fe-Mn bimetal nanocomposite. At the same time, reaction mechanism and degradation pathways were examined. The results showed that the bimetallic particles were highly paramagnetic for recover and evenly distributed, consisting of zero-valent Fe and Mn as well as their respective oxides. The removal kinetics of TC showed a fast process and reached a removal capacity of 330.17 mg/g within a reaction time of 60 min under TC concentration of 100 mg/L, pH = 3 and dosage of 0.3 g/L. The coexistence of both cations and anions had significant effect on the TC removal in the experimental conditions. Finally, OH and O2− played a major role in the redox reaction and the possible reaction mechanism and degradation pathways were demonstrated. To sum up, the Fe-Mn bimetal nanocomposite was proved to be promising and effective for treating TC-containing wastewater.

Ammonia leaching process for selective extraction of nickel and cobalt from polymetallic mixed hydroxide precipitate

Nitric acid pressure leaching process (NAPL) uses nitric acid as the leaching medium to produce cobalt and nickel raw materials. Based on the benefits of nitric acid pressure leaching process for laterite ore, this paper proposes a process of "nitric acid pressure leaching-neutralization precipitation-reductive ammonia leaching separation". Firstly, thermodynamic analysis confirmed the possibilities of nickel and cobalt leaching from ammonia solution. Then the impacts of leaching agent composition, temperature, time, and liquid-solid ratio on nickel and cobalt extraction ratios were investigated. Finally, the leaching behaviors of nickel and cobalt during ammonia leaching were investigated using the shrinking core model. In addition, the phase and morphology of the leach residue were studied using X-ray diffraction (XRD) and scanning electron microscope/energy dispersive spectrometer (SEM/EDS). The reductive ammonia leaching method for treating MHP results in high nickel and cobalt extraction ratios, good separation results, and recyclable material, all of which have significant industrial application value.

Thallium separation from wastewater using α-FeOOH@Biochar: Efficacy and mechanism

Thallium (Tl) is an untraditional toxic metal. Emerging Tl pollution has received increasing concerns. Despite its extreme biotoxicity, Tl is an irreplaceable element for specific high-tech fields (e.g., superconductors, semiconductors, and optical fibers) due to its peculiar physio-chemical properties. Besides, Tl has been also regarded as critical strategic metal owing to its low abundance and scarcity in the earth’s crust. Herein, a novel composite of α-FeOOH@BC was facilely synthesized via biochar modification with environmentally abundant iron oxides (α-FeOOH) to separate Tl(I) from wastewater. The results showed that overall large distribution coefficient values (Kd > 5000 mL/g) of Tl separation by α-FeOOH@BC in a wide pH range (5.0–11.0) were achieved, suggesting a generally promising Tl separation capacity. Multiple characterizations with Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) indicate that the dominant Tl separation mechanisms included electrostatic attraction, ion exchange and complexation. These findings indicate that the α-FeOOH@BC material may have important application in Tl separation from industrial wastewaters, which are usually moderately acidic with pH values ranging from 5.0 to 7.0. This study offers novel perspectives on using environmental abundant iron oxides modified biochar for easy and fast separation of Tl from industrial wastewater. All these findings can facilitate to develop waste-to-resources strategy for recycling Tl in the loop of circular economy and industrial symbiosis.

Experimental investigation on biodiesel production through simultaneous esterification and transesterification using mixed rare earth catalysts

In this study, biodiesel production through simultaneous esterification and transesterification of palm oil with 10 wt% of oleic acid using the mixed rare earth catalyst was investigated. The mixed rare earth catalysts were prepared via the co-precipitation method. The effects of the precipitating parameters such as temperature, stirring speed and pH on the physicochemical and morphology of the catalysts were studied. All catalysts were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), fourier transform-infrared spectroscopy (FTIR), N2 adsorption/desorption, CO2 temperature programmed desorption (CO2-TPD) and NH3 temperature programmed desorption. (NH3-TPD). The results indicated that the mixed rare earth catalyst prepared under the precipitation conditions: at pH 9, a stirring of 400 rpm and temperature of 30 °C showed the highest catalytic of 90% FAME content. High surface area of the catalyst, a significant larger amount of Ce and La contents in the catalyst and an appropriate amount of acid and basic sites on the catalyst led to the high catalytic activity. The catalyst could also accelerate the initial reaction rate to achieve the high FAME content of 50% within 30 min.

Green synthesis of silver nanoparticles from Mahonia fortunei extracts and characterization of its inhibitory effect on Chinese cabbage soft rot pathogen.

The pathogenic bacterium Pectobacterium carotovorum causes soft rot in cabbage and significantly reduces plant yield. In this study, we employed Mhonia fortunei extracts to synthesis silver nanoparticles (Mf-AgNPs) and investigated their functions against P. carotovorum. The results showed that the surface plasmon resonance (SPR) peak of AgNP was 412 nm under optimal synthesis conditions. Furthermore, the results of Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS) and High-resolution transmission electron microscopy (HR-TEM) revealed that the Mf-AgNPs had a spherical structure with an average diameter of 13.19 nm and the content of Ag0 ions accounted for 82.68% of the total elemental content. The X-Ray diffraction (XRD) results confirmed that AgNPs had a face-centered cubic (FCC) crystal structure, while Fourier transform infrared spectroscopy (FTIR) results indicated the presence of various biomolecules as reducing and stabilizing agents on the AgNP surface. Antibacterial activity was first evaluated by an inhibitory zone test, which revealed that 500 μg ml-1 of AgNPs had antibacterial activity against P. carotovorum and four model bacteria including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, respectively with an antibacterial function comparable to 1 mM AgNO3 solution. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for P. carotovorum were 8 μg ml-1, respectively. Furthermore, AgNPs at 8 μg ml-1 completely inhibited the growth of P. carotovorum, decreased their tolerance to 0.25 mM H2O2 as well as considerably reduced colony formation after 1 h of treatment and thereafter. Treatment with Mf-AgNPs resulted in bacterial cell membrane destruction and biofilm formation inhibition, respectively. With an FIC (fractional inhibitory concentration) index of 0.174, AgNP and zhongshengmycin showed a significant synergistic effect. The infection of P. carotovorum to cabbage explants was significantly inhibited in vitro by a combination of 2 μg ml-1 Mf-AgNP and 5 μg ml-1 zhongshengmycin. In conclusion, the synthesized Mf-AgNP exhibited significant antibacterial activity against P. carotovorum.

Experimental Research on the Compression Property of Geopolymer Concrete with Molybdenum Tailings as a Building Material

This paper experimentally studied the effects of different molybdenum tailings (MoT) content, standard curing and 60 °C water curing conditions on the compressive strength of fly ash-based geopolymers at different ages. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) and Fourier-transform infrared spectroscopy (FTIR) were applied to investigate the effect of the content of MoT and different curing conditions on the reaction products, microstructure and chemical composition of fly ash-based geopolymers. The results show that MoT content and curing conditions have synergistic effects on the compressive strength of fly ash-based geopolymers. For standard curing, the increase in MoT content is detrimental to the development of compressive strength, and an obvious weak interfacial transition zone between MoT and the gel product is observed in specimen containing 40 wt% MoT; meanwhile, under water curing conditions, the compressive strength of geopolymers first increases and then decreases with the increase in MoT, and the 28-day compressive strength can reach 90.3 MPa when the content of MoT is 10 wt%. The SEM results show that the curing conditions have a great influence on the microstructure of the geopolymer matrix, and the microstructure of the specimens under the water curing conditions is smoother and denser, with fewer pores. EDS analyses show that the gel product constituting the geopolymer matrix is N(C)-A-S-H gel; MoT can participate in the reaction, and the mass ratio of Ca/(Si + Al) of N(C)-A-S-H gel increases with the increase in MoT, resulting in a decrease in compressive strength. In addition, the results of the FTIR confirm that water curing can increase the degree of crosslinks in the gel phase.

Multi-Analytical Study on Excavated Human Bones in the Burial Environment at Shenna Ruins, Qinghai, China

Excavated human bones are important materials for revealing information about ancient human food, the ancient environment and the ancient climate, and the origins of ancient humans. Often, the chemical composition and biological characteristics of bones have changed to varying degrees, which means that they are contaminated and cannot be used for further analysis. Through research on the correlation between human bones excavated from a burial environment and their state of preservation, judging whether the excavated bones are contaminated is a prerequisite for scientific analysis, environmental archeology, and research on ancient human recipes. In this paper, human bones excavated from the Shenna ruins and the contamination of them in the burial environment has been judged using craniofacial measurement characteristics, pH measurement, scanning electron microscopy–energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), Fourier transform red external light spectrum (FTIR), and stable isotope tests (SIT). However, the organic compositions of the remains at Shenna are decomposed to a large degree, and the inorganic structure has been destroyed, which will eventually cause looseness and porosity, and the compositions of inorganic minerals in the human bones have not been changed or contaminated. The results indicate that the burial environment at Shenna accelerated the deterioration of human bones, but it has not affected the typical character of the human bone, and the human bones extracted can still be used for further trace element testing. Moreover, this can help to reduce the effort required to reveal information about ancient human food, as well as the need for further studies of the paleoenvironment and paleoclimate in the Shenna ruins.

Extraction of Gold from the Leachate of Copper Anode Slime by Quaternary Ammonium Rice Husk Lignin

ABSTRACT Extraction of gold by adsorption is being concerned because of easy operation, low cost and non-pollution for the present. Lignin and its derivatives are considered to be the most promising adsorbent due to abundance and environmental friendliness. In this work, gold was extracted from the leachate of copper anode slime by quaternary ammonium rice husk lignin (QARHL). QARHL was synthesized and characterized by Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS) and Thermogravimetric Analysis and Differential Scanning Calorimetry (TG-DSC). The influence of adsorption time, dosage of adsorbent and temperature on adsorption were investigated. The adsorption mechanism of QARHL for gold was explored by Scanning Electron Microscope (SEM), FTIR and X-ray Diffractometry (XRD). The results showed that QARHL had excellent thermostability and contained a large number of quaternary ammonium groups and hydroxyl groups. The saturated adsorption capacity reached 220.70 mg•g-1 and the time of equilibrium was 120 min. The adsorption was easy to occur spontaneously and obeyed the models of pseudo-second order and Langmuir. AuCl4- was reduced to Au(0) by phenolic hydroxyl after ion exchange. The new process could be used to recovery gold from gold-containing raw materials without pretreatment. It is possible to extract gold effectively, economically and environmentally friendly.

Parallel adsorption of low concentrated ciprofloxacin by a CoFe-LDH modified sludge biochar

The sludge biochar loaded with layered double hydroxides (CoFe-LDH@SBC) was used as a composite adsorbent for removing low concentrated ciprofloxacin (CIP) effectively in water environment. The sludge biochar (SBC) and CoFe-LDH@SBC were synthesized by pyrolysis and self-assembly; and the characterization of SBC and the composite material were analyzed through a series of analytical methods including scanning electron microscopy-Energy Dispersive Spectrometer, X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller, and Zeta potential. Due to various chemisorptions, CoFe-LDH@SBC showed superior adsorption performance for CIP with 14 mg/g, which was 2.8 times of that for SBC. Moreover, Artificial Neural Network (ANN) model was employed to predict the adsorption capacity and removal rate of CIP using experimental data obtained. Furthermore, according to density functional theory (DFT), parallel adsorption was proved to be dominant in the adsorption process, which indicated that the adsorption was a favorable and exothermic chemisorptions process.

Can calcium-based constructed wetlands improve fluoride removal performance?

The calcium-based substrate, plants and microorganisms and their interactions in constructed wetlands (CWs) could affect the removal performance and transformation of fluoride (F-). CWs with limestone additive enhanced F- removal during the first 40 days. The results of scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) revealed the presence of Ca2+ precipitate components, and X-ray diffraction (XRD) demonstrated the formation of CaF2, Ca5(PO4)3F, and Ca3(PO4)2 precipitation, which all attributed to the synergetic effects of adsorption and co-precipitation. However, the F- removal efficiency of both CWs were diminishing step by step and reached as high as influent concentration around 50th day. The F- effluent concentration stabilized at 3.81 ± 0.02 mg/L and 3.72 ± 0.03 mg/L in calcium-based group and control group, respectively. The weak F- removal performance in plant-uprooted CWs confirmed that plants promoted the release of adsorbed F- and the dissolution of Ca5(PO4)3F by reducing overall pH value of CWs substrate whether with limestone additive or not. Furthermore, the lower relative abundance of fluoride-tolerant bacteria was observed in plant-uprooted CWs compared with planted CWs. This study had important implications for understanding the F- transformation in calcium-based CWs, and could be referenced by the application, design, and construction of constructed wetlands in fluoride-contaminated regions.

Effect of femtosecond laser ablate ultra-fine microgrooves on surface properties of dental zirconia materials

ObjectivesZirconia is an important dental implant material, yet it surfaces milling method is still under investigation. To explore the feasibility of laser etching in processing fine micro grooves on the surface of zirconia and to observe fine micro groove structure’ influence on mouse embryonic osteoblasts, the survey was conducted. Methods31 zirconia discs were made and polished to mirror surface. Then, they were divided into 3 groups: the mirror group, the femtosecond laser ablated microgroove group and the air blasted + acid etched group. Then, the surface properties of zirconia discs were analyzed by Scanning Electron Microscope/Energy Dispersive Spectrometer (SEM/EDS), X-Ray Diffraction (XRD), Atomic Force Microscope (AFM), water contact angle test and micro-Vickers hardness test. The biocompatibility of each machined zirconia was tested by cell proliferation test and SEM analyze of cell morphology. Then, the effect of these surface treatment to MC-3T3-E1’s osteogenic differentiation was evaluated by Q-PCR test. ResultsSEM image showed that the femtosecond laser is a reliable method for forming regular-arranged microgrooves with pitch width of around 5 μm. EDS and XRD indicated that there were stable and purified tetragonal crystal system on the laser-roughened surface. AFM suggested that laser machining generated rougher surface (Ra) (271.7 ± 67.2 nm) than other groups. Furthermore, the contact angle showed laser ablated grooves induced anisotropic wetting. The micro-Vickers hardness test ascertained that laser-ablation strengthened zirconia surface. In vitro experiment showed that MC-3T3-E1 grown along the long axis of microgrooves on the first day. Besides, Real time PCR implied that osteogenesis-related gene expression OPN and ALP was much higher than the rest groups. SignificanceFemtosecond laser is able to machine zirconia with ultra-fine microgrooves (around 2.5 μm). These structures promoted MC-3T3-E1 cell to line along the microstructure and differentiate into osteogenic cells. Thus, femtosecond laser might be a potential processing options for zirconia micro-texturing.