Lead Adsorption onto Clay Soil Treated with Sugarcane Organic Waste Biochar

This work aims to maximize the utilization of sugar cane cultivation and manufacture waste in Aswan Governorate, Egypt and turn it into biochar, which can be used to clean the environment from dangerous metals. Sugarcane organic wastes (filter cake, bagasse and sphere) biochars as waste bio-adsorbent materials were obtained using the pyrolysis at 350 and 700°C and 90 min residence time under limited oxygen conditions. Two batch trails were conducted to study the effects of biochar pH and shaking time on the adsorption of Pb ion from solution in precedence of soil and biochar. Models to study the kinetics of the adsorption process as pseudo-first-order and pseudo-second-order models were used.The results showed that the absorbed or precipitated (at high suspension pH) amount of Pb decreased in the order: soil treated with biochar bagasse pyrolysis at 350°C (BB350) > soil treated with biochar sphere pyrolysis at 350°C (SB350) > soil treated with biochar filter cake pyrolysis at 350°C (FB350) > soil only. At pH 9 maximum amounts of Pb of 1.794, 1.706 and 1.688 mg/g were adsorbed or precipitated on the soil treated with BB350, SB350 and FB350 respectively. However, Pb was maximum adsorbed or precipitated (1.33 mg/g) on the soil only at pH 8. The highest removal efficiency of Pb2+ from the solution was85% with treated the soil with SB350 while the lowest one was 55.5% occurred with the soil that was not treated with biochar at a shaking time of 80 minutes. The adsorption of Pb2+ by the soil in presence or absence biochars different fitted the pseudo second order kinetic model for all tested treatments (R2 ranged from 0.9901 for the soil treated with BB350 to 0.9994 for that treated with SB350).

Management of the Forest Soils Fertility Based on Ecological Models in the South-Eastern Part of the Great Caucasus

The bloks which are a structural part of the ecological fertility model in the mountain-forest brown and mountain-forest brown soils on the south-eastern slope of the Great Caucasus besides an importance of the ecological models composition have been analyzed in the article. By the main purpose of the given investigations a creation of ecological models of fertility was mountain-forest brown soils (middle mountain broken) and mountainforest brown soils (low mountain (mean broken), interrelation and dependence of biocenosis condition on the environment factors are studied a role of the main parameters (climate, relief, soil and etc) is revealed, the real and optimal parameters of the environment are established for the ecological models blocks creation. The model consists of 7 (seven) blocks: agroecological block soil structure block, soil regimes block, soil features block. value block, agromelioration block and forests biometric block. During the model blocks compiling the main diagnostic indiced as a granulometric composition, humus quantity and supply, water suspension pH, NPK, bulky mass, porosity and water-stable aggregates (> 0,25mm and > 1,00mm) in the mountain-forest brown and mountain-forest brown soils have been taken into account. A comparative character of the ecological fertility models in two different soil types which are dominant in forest ecosystems has been given.

Crystal growth and aggregation in suspensions of δ-MnO2 nanoparticles: implications for surface reactivity

Sodium content and suspension pH control crystallite size and aggregation in δ-MnO2 nanoparticles.

Effect of Experimental Conditions on the Chemical Composition of Hydroxyapatite Synthesized by Chemical Precipitation

ABSTRACTHydroxyapatite [HAp, Ca5(PO4)3(OH)] was synthesized by chemical precipitation, using H3PO4 and Ca(OH)2 as chemical precursors. The precursors were slowly mixed in suitable proportions aiming to obtain Ca/P molar ratios of 1.5, 1.67 or 2.0 in the reacting suspension. This was followed by 21.5 h of aging. Both reaction and aging stages were carried out under an atmosphere of still ambient air and under continuous stirring, either at room temperature, 60 or 90 °C. The precipitates were characterized by ICP-AES and XRD. The results suggested that the most suitable Ca/P molar ratio for the production of pure phase HAp is Ca/P = 1.67, as long as the initial Ca(OH)2 particle size and/or the suspension pH are carefully controlled, especially when the synthesis is carried out above room temperature.

Effects of Milling pH and Hydrothermal Treatment on Formation of Nanostructured Boehmite Binder for Alumina Extrusion

The in situ formation of nanostructured aluminum hydroxides on the surface of alumina particles, which can work as inorganic binder, was reported in this paper. The effect of the suspension pH during milling of alumina powder and subsequent hydrothermal treatment for the hydroxide formation and microstructure was depicted. Under acidic pH condition, the formation of hydroxides was not observed. When the pH of suspension changed from acidic to basic during milling, bayerite [Al(OH)3] nanoparticles were formed, but only a fraction of this hydroxide was converted to boehmite (AlOOH) during subsequent hydrothermal treatment. The aluminum hydroxide and oxyhydroxide formed in this condition improved the smoothness of extruded rods and the strength of presintered segments. For the powder milled under basic pH condition, the mechanochemically formed bayerite was completely converted into boehmite nanoparticles during the hydrothermal treatment. The presence of boehmite nanoparticles contributed to improving plasticity during extrusion, which allowed the reduction of organic binder and increased the strength of presintered alumina rods.

CHARACTERIZATIONS AND STABILITY OF COLLOIDAL COAL-MEASURE KAOLINITE IN AQUEOUS SUSPENSIONS: A REVIEW

Coal-measure kaolinite is a main gangue mineral in coal deposits. Because of the colloidal particle size, the kaolinite is very stable in coal tailing slurries, leading to a high turbidity of recycled water in coal washing plants. The coagulation of colloidal kaolinite in aqueous suspensions is an essential problem in many coal washing plants. This review highlights the characterizations and stability of colloidal coal-measure kaolinite in aqueous suspensions. The characterizations include mineralogy, electrokinetics and hydration layers on kaolinite surfaces. The coagulation of colloidal kaolinite in aqueous suspensions is reviewed and discussed on the basis of the DLVO theory and the characterization. In addition,the main parameters of affecting the coagulation, such as suspension pH, electrolytic ions and temperature, are summarized.

Effect of the Deposition Time on LSCF–SDC Carbonate Thin Film Formation by the Electrophoretic Deposition Method

La0.6Sr0.4Co0.2Fe0.8O3-δ–samarium-doped ceria (SDC) carbonate thin films are produced on SDC carbonate substrates by the electrophoretic deposition (EPD) method. EPD is performed by fixing the voltage and suspension pH while varying the deposition time to obtain a >20 μm-thick layer. The deposition time of 30 min yields more particle deposits than 10, 15, 20, and 25 min. Thin films with an average thickness of 22.9050 μm are obtained from the EPD technique when the voltage is 20 V and the suspension pH is 5.

NOVEL COMPOSITE-BASED CATHODES FOR MOLTEN CARBONATE FUEL CELLS BY ELECTROCHEMICAL MULTICOMPONENT MODIFICATION

A multicomponent modification on the surface of porous nickel with nanoparticles is conducted by an electrophoretic deposition (EPD) technique to prepare new composite-based cathodes for molten carbonate fuel cells (MCFCs). Two new ternary composite-based cathodes, (nano- LiCoO2-LiFeO2 )- Ni and (nano- LiCoO2-CeO2 )- Ni , are inclined to possess good morphology and homogeneous element distribution when prepared under moderate current density resulting from a medium deposition voltage and suspension pH value in this work. Both composite-based cathodes manifest excellent anti-deformation and anti-dissolution performances under conditions of a simulated MCFC startup stage and are thus expected to be useful for application in the MCFC industry.

Genotypic and phenotypic analysis of S. mutans isolated from dental biofilms formed in vivo under high cariogenic conditions

The oral cavity harbors several Streptococcus mutans genotypes, which could present distinct virulence properties. However, little is known about the diversity and virulence traits of S. mutans genotypes isolated in vivo under controlled conditions of high cariogenic challenge. This study evaluated the genotypic diversity of S. mutans isolated from dental biofilms formed in vivo under sucrose exposure, as well as their acidogenicity and aciduricity. To form biofilms, subjects rinsed their mouths with distilled water or sucrose solution 8 times/day for 3 days. S. mutans collected from saliva and biofilms were genotyped by arbitrarily-primed PCR. Genotypes identified in the biofilms were evaluated regarding their ability to lower the suspension pH through glycolysis and their acid susceptibility and F-ATPase activity. Most subjects harbored only one genotype in saliva, which was detected in almost all biofilm samples at high proportions. Genotypes isolated only in the presence of sucrose had higher acidogenicity than those isolated only in the presence of water. Genotypes from biofilms formed with sucrose were more aciduric after 30 and 60 min of incubation at pH 2.8 and 5.0, respectively. The present results suggest that biofilms formed under high cariogenic conditions may harbor more aciduric and acidogenic S. mutans genotypes.