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Soil–rock mixture, a non-homogeneous medium with discrete characteristics, is commonly used in high-fill projects. This study analyzes the impact of rock morphology and distribution on the ultimate bearing capacity and sliding failure surface morphology of soil–rock embankments using the discrete element method (DEM). The results indicate that the embankment's ultimate bearing capacity increases with higher rock content. A larger ultimate bearing capacity is observed when rocks aggregate at the top of the sliding zone and the slope's toe. The influence of rock inclination angle on the ultimate bearing capacity follows this order: 30° > 45° > 60° > 0°. The rotation of block stones mainly occurs in the roadbed's shear zone. This study examines the shear zone morphology of the roadbed influenced by the stone content and spatial distribution of block stones. In this paper, we establish a sliding surface equation that considers the stone content and spatial distribution, providing guidance for assessing roadbed stability using the limit equilibrium method. [ABSTRACT FROM AUTHOR]

The conversion and storage of photothermal energy using phase change materials (PCMs) represent an optimal approach for harnessing clean and sustainable solar energy. Herein, we encapsulated polyethylene glycol (PEG) in montmorillonite aerogels (3D-Mt) through vacuum impregnation to prepare 3D-Mt/PEG composite PCMs. When used as a support matrix, 3D-Mt can effectively prevent PEG leakage and act as a flame-retardant barrier to reduce the flammability of PEG. Simultaneously, 3D-Mt/PEG demonstrates outstanding shape retention, increased thermal energy storage density, and commendable thermal and chemical stability. The phase transition enthalpy of 3D-Mt/PEG can reach 167.53 J/g and remains stable even after 50 heating–cooling cycles. Furthermore, the vertical sheet-like structure of 3D-Mt establishes directional heat transport channels, facilitating efficient phonon transfer. This configuration results in highly anisotropic thermal conductivities that ensure swift thermal responses and efficient heat conduction. This study addresses the shortcomings of PCMs, including the issues of leakage and inadequate flame retardancy. It achieves the development and design of 3D-Mt/PEG with ultrahigh strength, superior flame retardancy, and directional heat transfer. Therefore, this work offers a design strategy for the preparation of high-performance composite PCMs. The 3D-Mt/PEG with vertically aligned and well-ordered array structure developed in this research shows great potential for thermal management and photothermal conversion applications. [ABSTRACT FROM AUTHOR]

Lithium-aluminum layered double hydroxides (LiAl-LDH) have been be successfully applied in commercial-scale for lithium extraction from salt lake brine, however, further advancement of their applications is hampered by suboptimal Li+ adsorption performance and ambiguous extraction process. Herein, a doping engineering strategy was developed to fabricate novel Zn2+-doped LiAl-LDH (LiZnAl-LDH) with remarkable higher Li+ adsorption capacity (13.4 mg/g) and selectivity (separation factors of 213, 834, 171 for Li+/K+, Li+/Na+, Li+/Mg2+, respectively), as well as lossless reusability in Luobupo brine compared to the pristine LiAl-LDH. Further, combining experiments and simulation calculations, it was revealed that the specific surface area, hydrophilic, and surface attraction for Li+ of LiZnAl-LDH were significantly improved, reducing the adsorption energy (Ead) and Gibbs free energy (ΔG), thus facilitating the transfer of Li+ from brine into interface followed by insertion into voids. Importantly, the intrinsic oxygen vacancies derived from Zn-doping depressed the diffusion energy barrier of Li+, which accelerated the diffusion process of Li+ in the internal bulk of LiZnAl-LDH. This work provides a general strategy to overcome the existing limitations of Li+ recovery and deepens the understanding of Li+ extraction on LiAl-LDH. [ABSTRACT FROM AUTHOR]

In recent years, the solid wastes from the coal industry have been widely used as soil amendments. Nevertheless, the impact of utilizing coal slime for copper tailing restoration in terms of plant growth, physicochemical characteristics of the tailing soil, and microbial succession remains uncertain. Herein, the coal slime was employed as a modifier into copper tailings. Their effect on the growth and physiological response of Ryegrass, and the soil physicochemical properties as well as the bacterial community structure were investigated. The results indicated that after a 30-day of restoration, the addition of coal slime at a ratio of 40% enhanced plant growth, with a 21.69% rise in chlorophyll content, and a 62.44% increase in peroxidase activity. The addition of 40% coal slime also increased the content of nutrient elements in copper tailings. Following a 20-day period of restoration, the concentrations of available copper and available zinc in the modified tailings decreased by 39.6% and 48.51%, respectively, with 40% of coal slime added. In the meantime, there was an observed augmentation in the species diversity of the bacterial community in the modified tailings. The alterations in both community structure and function were primarily influenced by variations in pH value, available nitrogen, phosphorus, potassium, and available copper. The addition of 40% coal slime makes the physicochemical properties and microbial community evolution of copper tailings reach a balance point. The utilization of coal slime has the potential to enhance the physicochemical characteristics of tailings and promote the proliferation of microbial communities, hence facilitating the soil evolution of two distinct solid waste materials. Consequently, the application of coal slime in the restoration of heavy metal tailings is a viable approach, offering both cost-effectiveness and efficacy as an enhancer. [ABSTRACT FROM AUTHOR]

Coagulation with aluminum salts is an important method for fluoride removal from groundwater. However, the hydration of aluminum salts generating a large number of H+ usually leads to limited defluorination performance due to the optimum pH of active aluminum phase for fluoride removal around 5.5–6.5. In this work, enhanced fluoride removal from groundwater through precise regulation of active aluminum phase by CaCO3 was investigated. Precipitation products were characterized by XPS, FTIR, XRD, and SEM, respectively, and the mechanism of the high fluoride removal efficiency was discussed and compared with the traditional coagulation of Al2(SO4)3. In the Al2(SO4)3 + CaCO3 (ASCC) system, CaCO3 can stably regulate the pH at the optimum range for active aluminum phase existence and has the best fluoride removal effect. CaCO3 accurately regulated the activity of the aluminum phase by slowly releasing OH− and fine tuning pH, thereby achieving effective fluoride removal. Undissolved CaCO3 particles exist as the carrier of defluorination flocs to accelerate precipitation and improve stability. The work here provides a new method for fluoride removal and may shed light on the application of CaCO3 coagulants for other pollutants. [ABSTRACT FROM AUTHOR]

Cd(II) pollution in water will cause serious threats to the environment and human health. The general remediation protocol for Cd(II) pollution by hydroxide (Ca(OH)2 or NaOH) is still faced with filtering difficulties and high effluent pH. To develop an applicable method for the Cd(II) removal in water, we prepared an activated calcium carbonate (CaCO3) material by changing the crystallinity, particle size, and surface activity of CaCO3, and investigated the corresponding Cd(II) removal capacity from aqueous solutions. The results showed that more than 99.9% of Cd(II) was removed within 10 min in an initial concentration of 50 mg L−1. Moreover, the effluent pH is close to neutral after removal of Cd(II), and the sediment is filtered well. Comparative experiments and characterizations have demonstrated that the excellent Cd(II) removal performance of activated CaCO3 is due to the mechanical activation changes the surface activity of the original stable CaCO3, promotes the slow-release dissolution equilibrium of the active carbonate groups, and thus the coprecipitation of cadmium hydroxide and cadmium carbonate on CaCO3 particles. This research demonstrates that mechanical activation of CaCO3 could be used as a repair material for efficient removal of heavy metal pollution in water, which can solve the problems of filtration and high effluent pH of alkaline precipitation. [ABSTRACT FROM AUTHOR]

As important parts of microbe–mineral associations, microalgae–montmorillonite composites are common in nature environment, which have been overlooked for a long time. In this study, the binding of Cd(II) in the montmorillonite, microalgae and their 1:5, 1:10 mass ratio composites interface were investigated. The results showed that maximum adsorption capacity of 1:5 and 1:10 mass ratio binary composites were 65.25 mg g−1 and 55.49 mg g−1, respectively, which both higher the theoretically calculated capacity from single montmorillonite and microalgae at pH 5.5. Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that phosphoryl and carboxyl functional groups on the algal cellular surface played major roles in both microalgae–montmorillonite composite formation and Cd(II) adsorption. Extended X-ray absorption fine structure (EXAFS) further probed that higher sorption on composites were attributed to Cd(II) bridging between microalgae and montmorillonite, in which monodentate phosphoryl-Cd and carboxyl-Cd complexes on microalgae side, leading Cd(II) to a more stabilized state. In addition, the montmorillonite promoted dispersion of microalgae, releasing more carboxyl and phosphoryl functional groups as Cd(II) binding sites on the microalgae surface. These findings highlight the function of microalgae in the microalgae–clay mineral associations for Cd(II) fixation and provide further insight into the sequestration and migration of toxic metals in natural environments. [ABSTRACT FROM AUTHOR]

This study was conducted to explore the ecosystem services of urban forests in Adama city, central Ethiopia. Attempts were made to quantify the carbon storage and sequestration, air pollution removal and hydrological benefits of urban trees. The urban forest structure and composition of the city was surveyed and analyzed. The i-Tree Eco Model was employed to analyze the ecosystem services based on the current urban forests structure of the city. The result revealed that the urban trees of the Adama city stored a total of 116,000 tons of carbon. The tree species identified with higher CO2 sequestration per year were Melia azedarach (15%), Eucalyptusglobulus (8%), Carica papaya (7%), and Delonix regia (6%). In addition, 22%, 12%, 10% and 4% of carbon were stored by Eucalyptus globulus, Melia azedarach, Carica papaya and Delonix regia tree species respectively. Moreover, trees and shrubs species in the city removed about 188 thousand tons of air pollutants caused by O3, CO, NO2, PM2.5 and SO2 per year. In Adama, 35% of the urban trees' volatile organic compaound emissions were from Eucalyptus cinerea and Eucalyptus globulus. The monetary value of Adama urban forest in terms of carbon storage, carbon sequestration, and pollution removal was estimated to 43,781, 3,121 yr−1 and 320,915,596 USD yr−1, respectively. It was concluded that significant quantity of CO2 and air pollutants were found being removed by the exotic tree and shrub species. However, every plant species found in the city does not mean ecologically important due their VOC emitting nature. Thus, the results of the study are valuable in increasing the awareness of the decision making bodies, the public and any stakeholders of the eco-benefits of urban trees in the mitigation of climate changes. [ABSTRACT FROM AUTHOR]

Carboxymethyl cellulose-based hydrogel enhanced by two-dimensional montmorillonite nanosheets (CMC-MMTs Gel) has been successfully synthesized throguh polymerization for methylene blue (MB) removal from water. Structure characterization shows that the introduction of two-dimensional montmorillonite nanosheets (2D MMTs) into CMC-based hyddrogel results in a roguh surface and increased porosity. Adsorption tests demonstrate that the adsorption rate and adsorption capacity of CMC-based hydrogel increase significantly with the increase in 2D MMTs content, and a high adsorption capacity of 410 mg g−1 can be reached. After 5 cycles, CMC-MMTs Gel still exhibits good removal performance indicating a good reusability and structural stability. The enhanced MB removal performance and improved structural stability might be due to 2D MMTs and the increased porosity. FTIR and XPS characterizations demonstrate that the adsorption mechanism of MB onto CMC-MMTs Gel might be attributed to electrostatic adsorption and ion-exchange between MB molecules and MMTs, and the interactions between MB molecules and the hydroxyl and carboxyl groups of CMC. [ABSTRACT FROM AUTHOR]

Dry afromontane forests are among the most poorly managed and endangered ecosystems. Therefore, we assessed the composition, diversity, and conservation status of woody plant species of the Debre Libanos church forests and surrounding forest lands in Oromiya Regional National State, central Ethiopia in 62 nested circular sample plots spaced 200 m apart along two transect lines. Large circular plots 314 m2 were used to sample trees with DBH of at least 10 cm, and subplots of 28.26 m2 were laid in each main plot were used to assess saplings and shrubs; a small subplot of 3.14 m2 was used to assess seedlings. In total, 70 woody plant species belonging to 62 genera and 43 families were recorded. Of these, 59, 28 and 32 were in the church, government and private forest types, respectively. The most dominant families were Fabaceae and Verbenaceae, each represented by five species. In the forests considered, trees accounted for 61%, and shrubs with diameter at breast height (DBH) of 1–10 cm accounted for ca. 33%. Among growth forms of woody species, shrubs and seedlings, followed by trees constituted much of the density of woody species in all the three ownership types of forests. The church forest had the most species (59) and highest Shannon (3.12) and Simpson (0.92) species diversity indices, and the government and private forests had a nearly similar total number of species and Shannon and Simpson species diversity indices. Most of the species with higher importance value indices (IVI) were indigenous in origin within the church forest (Juniperus procera = 82), government forest (J. procera = 66) and private forest (Acacia abyssinica = 84). The composition, diversity, and population structure of woody species in the church forest were significantly higher than in the other forest lands. However, interventions of the government and private sectors to conserve forest systems in the areas, particularly the government-owned forest and specific species such as Olea europaea need active enrichment plantings due to their limited natural regeneration. Without improved management interventions, livelihood income diversification and ecosystem services obtained from the forest will not be sustainable. [ABSTRACT FROM AUTHOR]

Iron recovery from copper slag generated during copper production by the pyrometallurgical method has been widely investigated to achieve resource utilization. Liberation and enrichment of metallic iron from reductively roasted copper slag were explored in this work. Results show that metallic iron, quartz solid solution, and cristobalite solid solution are the main phases in reductively roasted copper slag, and most metallic iron particles are wrapped by silica. A concentrate with 74.39% Fe content and 83.14% Fe recovery is obtained through grinding–magnetic separation. For comparison, the metallic iron particles are liberated through alkali leaching of silica. The Fe content in leaching residue reaches 78.17% by removing 88.96% SiO2 and further increases to 90.45% by magnetic separation with Fe recovery of 85.20%. Therefore, alkali leaching–magnetic separation is suitable for treating reductively roasted copper slag because of the high Fe content in concentrate and comprehensive recovery of silica. [ABSTRACT FROM AUTHOR]

Copper slag (CS) with Fe-bearing fayalite and magnetite is the main waste generated during the pyrometallurgical processing of metallic copper. In this paper, the solid-state reduction kinetics of fayalite with and without addition of 10 wt.% metallic iron were studied using the isothermal method. The phase transformation of fayalite was verified by x-ray diffraction, scanning electron microscopy, and energy dispersive spectrometer. Results show that the carbothermal reduction of fayalite is controlled by phase boundary reaction (tridimensional shape), and the activation energy decreases from 165.22 kJ mol−1 to 145.74 kJ mol−1 after adding 10 wt.% metallic iron. During the carbothermal reduction process, fayalite decomposes into metallic iron and quartz solid solution, followed by the conversion of quartz solid solution into cristobalite solid solution with increasing temperature. The addition of metallic iron creates a nucleating effect and accelerates the decomposition of fayalite. This work contributes to efforts to optimize the carbothermal reduction of CS. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) occur naturally and widely on the surface of microbial cells; their reducibility may play a crucial role in graphene oxide reduction. In this work, the conversion of graphene oxide (GO) into reduction graphene oxide (rGO) with EPS (extracted from Bacillus sp.NT 10) as green reductant had been conducted to explore their potential application for graphene preparation. The results showed the GO could be reduced by EPS, especially in the presence of NH4+, and a synergetic effect was found between EPS and NH4+. Further studies hinted the rGO could be also obtained from GO by EPS reduction even under a mild alkaline condition (pH = 8), lightly higher room temperature (40 °C) and a certain amount of time (24 h). The good reduction performance was found to be ascribed to the real deoxygenation of oxygenous functional groups and restoration of electronic conjugation within GO, according to the analysis of XRD, XPS and FT-IR as well as Raman spectra, while the electron-rich tryptophan-like protein and aromatic protein on the surface of EPS as well as the assistance of NH4+ should account for the deoxygenation and restoration in terms of the detection on Zeta potential, AFM and 3D-EEM. These findings revealed the reduction of GO with EPS would be a green, environment-friendly and promising path to obtain rGO, which may open a novel route for the preparing graphene alternatively. [ABSTRACT FROM AUTHOR]

This work explored the feasibility of utilizing the copper tailings (CT) for removing copper from the waste mine water based on the mechanochemical activation. Batch experiments were performed to evaluate the influences of various experimental parameters like the dosage of CT, reaction time, initial concentration of Cu, and anion species. By cogriding copper solution with CT in the stirred mill (mechanochemical activation), over 99.5% of copper was removed and the residual copper concentration in the solution was less than 0.5 mg/L, reaching the discharge limit. This reaction was a chemical precipitation process. The calcite of CT played a major role in precipitating copper and had a better removal effect on copper in the copper sulfate solution than copper nitrate solution. For copper sulfate solution, the copper deposit was mainly posnjakite (Cu4(SO4)(OH)6·H2O). In the copper nitrate solution, the copper sediment might consist mainly of basic copper nitrate. The stability of the two reaction products was measured by leaching test. The result showed that the sediment obtained by this method was relatively stable and was not hazardous wastes. [ABSTRACT FROM AUTHOR]

Swelling of montmorillonite (Mt) is an important factor for many industrial applications. In this study, crystalline swelling of alkali-metal- and alkaline-earth-metal-Mt has been studied through energy optimization and molecular dynamics simulations using the clay force field by Materials Studio 8.0. The delamination and exfoliation of Mt are primarily realized by crystalline swelling caused by the enhanced interlayer cation hydration. The initial position of the interlayer cations and water molecules is the dominated factor for the accuracy of the Mt simulations. Crystalline swelling can be carried out in alkali-metal-Mt and Mg-Mt but with difficulty in Ca-Mt, Sr-Mt and Ba-Mt. The crystalline swelling capacity values are in the order Na-Mt > K-Mt > Cs-Mt > Mg-Mt. This order of crystalline swelling of Mt in the same group can be attributed to the differences between the interlayer cation hydration strengths. In addition, the differences in the crystalline swelling between the alkali-metal-Mt and alkaline-earth-metal-Mt can be primarily attributed to the valence of the interlayer cations. [ABSTRACT FROM AUTHOR]

The Hg2+ removal performance of fishbone charcoal prepared from discarded fishbone has been investigated in this work. The XRD, FTIR, and BET results demonstrated that the main composition of fishbone charcoal was hydroxyapatite and the specific surface area was 117 m2/g. The adsorption experiments indicated that fishbone charcoal had an extremely high adsorption capacity for Hg2+ (243.77 mg/g). The excellent Hg2+ adsorption capacity might be ascribed to the ion exchange of Hg2+ to the Ca2+ in the structure of fishbone charcoal, complexation of Hg2+ with ≡Ca(OH)2+ on the surface of fishbone charcoal, as well as electrostatic interaction between electronegative fishbone charcoal surface and cation Hg2+. This work transformed kitchen garbage (i.e., fishbone) into an effective mercury adsorbent with considerable capacity, giving a perspective sight for the utilization of solid waste. [ABSTRACT FROM AUTHOR]

Except for the specific surface area and pore size, the hydroxyl groups on the surface of the ferric oxides were determined as the key factor in arsenic adsorption in this study. Two synthetic mesoporous ferric oxides, amorphous ferric oxyhydroxide (AFO) and goethite, were used to adsorb As(III) and As(V) in aqueous solution. The experimental results showed that the AFO had a higher hydroxyl group density, resulting in a higher arsenic adsorption capacity than that on the goethite for both As(III) and As(V). Also, it was found that the adsorption of As(III) on both the goethite and AFO was faster than that of As(V), and the adsorption rate fitted the pseudo-second-order kinetics. The findings indicated a promising modification of adsorbents for arsenic remediation. [ABSTRACT FROM AUTHOR]

New microscale zero-valent iron adsorbent on fly ash and bentonite matrix for removal of crystal violet (CV) and methylene blue (MB) was synthesized through direct reduction of iron oxide using coke and palm kernel shell. The adsorbent was prepared as cylindrical shaped pellets to remove the CV and MB from the aqueous solution. Nitrogen adsorption-desorption isotherm and scanning electron microscopy (SEM) studies showed that the adsorbent is highly porous, and the iron particles are finely dispersed on the supporting material surfaces. FTIR and UV studies indicated that the C=C bonds in CV and C=N(CH) bonds in MB were affected in the adsorption process. MB switched to the reduced MBH species while CV was reduced to two small-size molecular compounds, explaining the higher CV adsorption in comparison to that of MB. The reduction of these compounds was coupled to the oxidation of Fe to FeO as revealed by XRD characterization of the adsorbent after adsorption. CV and MB adsorption isotherms fitted well with the Langmuir adsorption model. Different adsorption and reduction kinetic models were examined for the MB and CV removal processes. A better fit of the experimental data with the pseudo-second-order model was observed. CV and MB adsorption increased with temperature in the 30-50 °C range. At 50 °C, adsorption capacities of CV and MB reached to 89.9 and 42.8 mg/g, respectively. This new adsorbent showed a superior adsorption capacity for CV and MB when compared to other adsorbents. [ABSTRACT FROM AUTHOR]

The preparation and characterization of nanoscale zero-valent iron-loaded porous sepiolite, as well as its application in the decolorization of methylene blue in aqueous solution, have been studied in this work through the measurements of field emission scanning electron microscope with energy dispersive spectrometry, x-ray photoelectron spectrometry, Fourier transform infrared spectroscopy and specific surface area. The results showed that nanoscale zero-valent iron particles were successfully loaded on the surface and interior pores of sepiolite through physical adsorption. It was revealed that the decoloration capacity of methylene blue on nanoscale zero-valent iron-loaded porous sepiolite in water was comparable to that of nanoscale zero-valent iron, and nine times higher than that of natural sepiolite. This indicates that porous sepiolite was a good supporter for the loading of nanoscale zero-valent iron and nanoscale zero-valent iron-loaded sepiolite was a good decolorant because of its high decoloration efficiency and easy separation. [ABSTRACT FROM AUTHOR]

The effect of water and isopropanol intercalation on montmorillonite (MMT) delamination was investigated in order to compare the roles of hydration and solvation in the delamination. Transmittance results showed that water has a significant effect on the delamination of MMT compared with isopropanol. This observation was attributed to the difference of the intercalation of water and isopropanol. Thermogravimetric (TG) results illustrate that the intercalation mass of water was greater than that of isopropanol when the pressure remained constant. Weighing test results show that the intercalation mass of water was smaller than that of isopropanol when the volume of MMT remained constant. Molecule dynamic simulation results show that the water and isopropanol molecules were interacting with Na and siloxane surface of MMT, respectively. It was demonstrated that the hydration of the MMT interlayer followed two steps: in step 1, the Na in the interlayer was hydrated, thereby expanding the interlayer spacing; in step 2, additional water molecules were absorbed into the expanded interlayer space. It was found that step 2 could not be actuated until the completion of step 1. For the solvation of the MMT interlayer with isopropanol, however, only one step was required, in which isopropanol was absorbed onto the siloxane sites of the interlayer while maintaining the interlayer spacing. [ABSTRACT FROM AUTHOR]

Air lime mortar is an important material for restoring ancient buildings, but its application is limited because of its low compressive strength, high shrinkage, and high porosity. In this work, improvement of the compressive strength of lime mortar by adding carboxymethyl cellulose (CMC) solution has been investigated. We characterized fine particles of Ca(OH) and lime mortars by scanning electron microscopy, infrared spectroscopy, the adsorption capacity, and the zeta potential. The experimental results show that the addition of CMC improves the compressive strength of lime mortar. Chemisorption of CMC to Ca(OH) particles leads to CMC bridging Ca(OH) particles, which is the key to form a more compact structure according to the porosity of the lime mortar. It was found that CMC acts as a skeleton in lime mortar because of the bridging effect of the molecules and the extended conformation of the molecules at high pH, which contributes to improvement of the compressive strength of lime mortar. [ABSTRACT FROM AUTHOR]

This study reports a comprehensive set of experimentally measured surface properties of six oleaginous green microalgae. The results showed that the hydrophobic character of the six microalgae, determined by the contact angle method, was more accurate than by using the microbial adhesion to solvents (MATS) method. However, they both indicated that all studied microalgae presented an electron donor parameter. Due to the abundant surface carboxyl, phosphoryl, and hydroxyl groups, all microalgae presented a negatively charged surface. Monoraphidium dybowoskii XJ-377 was the most hydrophobic strain with a negative Δ G and the lowest surface free energy. Kirchneriella dianae XJ-93 had the lowest total surface functional group concentration and the lowest surface area, which can lower the harvesting cost. Overall, cellular surface properties should be evaluated and considered in oleaginous microalgal screening and identification in addition to the biomass and oil production normally considered. [ABSTRACT FROM AUTHOR]

This study investigated the changes in lipid and starch contents, lipid fraction, and lipid profile in the nitrogen-starved Scenedesmus obtusus XJ-15 at different temperatures (17, 25, and 33 °C). The optimal temperature for both growth and lipid accumulation under nitrogen-sufficient condition was found to be 25 °C. However, under nitrogen deprivation, the total and neutral lipids increased with increasing temperature, and achieved the highest lipid content of 47.60 % of dry cell weight and the highest TAG content of 79.66 % of total lipid at 33 °C. In the meantime, the stored cellular starch content decreased with the increasing temperature. Thus, high temperature induced carbon flux from starch toward TAG accumulation in microalgae during nitrogen starvation. In addition, the decreased polar lipids may also serve for TAG synthesis under high temperature, and high temperature further reduced the degree of the fatty acid unsaturation and favored a better biodiesel production. These results suggested that high-temperature stress can be a good strategy for enhancing biofuel production in oleaginous microalgae during nitrogen deficiency. [ABSTRACT FROM AUTHOR]

Dispersion of a solid particle in water may lead to the formation of hydration film on the particle surface, which can strongly increase the repulsive force between the particles and thus strongly affect the stability of dispersions. The hydration film thickness, which varies with the variation of property of suspension particles, is one of the most important parameters of hydration film, and is also one of the most difficult parameters that can be measured accurately. In this paper, a method, based on force-distance curve of atomic force microscopy, for determining the hydration film thickness of particles is developed. The method utilizes the difference of cantilever deflection before, between and after penetrating the hydration films between tip and sample, which reflect the difference of slope on the force-distance curve. 3 samples, mica, glass and stainless steel, were used for hydration thickness determination, and the results show that the hydration film thickness between silicon tip and mica, glass and stainless steel are 30.0±2.0, 29.0±1.0 and 32.5±2.5 nm, respectively. [ABSTRACT FROM AUTHOR]

Two types of granular adsorbents-supported zero-valent iron (ZVI) were prepared and applied to remove crystal violet (CV). One type of ZVI was synthesized by the chemical reduction method and deposited on the surface of granular porous adsorbent (Fe@GAC). The other type of ZVI was synthesized by direct reduction of iron ore tailing powder with the coke in high temperature reducing atmosphere and was embedded in granular porous adsorbent (Fe@GAR). Fe@GAC and Fe@GAR were characterized by SEM, EDX, XRD, FTIR, and BET. The effect of parameters like contact time, initial CV concentration, pH values, and temperature on the removal of CV was investigated. According to the results, the Langmuir model was in good agreement with the experimental data, where the maximum removal capacity of Fe@GAC and Fe@GAR was found to be 95.24 mg/g and 123.45 mg/g at 293 K, respectively. The kinetic studies indicated that the pseudo-second-order kinetic model agreed well with the experimental data. Thermodynamic parameters were calculated and analyzed, which suggested that the removal processes were spontaneous and endothermic. The mechanism of CV removal by Fe@GAC and Fe@GAR included adsorption and simultaneous chemical reduction. Compared with Fe@GAC, Fe@GAR owned more amount of ZVI, larger specific surface area and higher removal capacity, which made it a more promising adsorbent in wastewater treatment. [ABSTRACT FROM AUTHOR]