APCBEE Procedia最新文献

The potential of oxalic acid modified rice husk (ORH) to adsorb Methylene Blue (MB) from aqueous solution was investigated under various experimental conditions. Parameters studied included pH, initial dye concentrations, contact time, sorption isotherm, agitation rate and adsorbent dosage. A comparison study on the percentage uptake of natural rice husk and oxalic acid modified rice husk on MB dye showed that oxalic acid modified rice husk gave better removal efficiency. The percentage of dye uptake increased with increasing of pH and contact time. The optimum pH for MB removal was recorded at the range of pH 4 to pH 10 and the adsorption equilibrium was achieved after the first one and a half hours of contact time. From the kinetic study, the adsorption process correlated well with pseudo-second order kinetics equation. The experimental data were fitted into different isotherm model equations and the results revealed that the system under studied is better explained by Langmuir isotherm as compared to Freundlich isotherm. The maximum sorption capacity of ORH for MB was 29.15 mg/g.

During the manufacture of recycled paper, paper sludge is discharged as an industrial waste. The amount of sludge discharged from manufacturing plants increases annually. In this study, the organic constituents, such as cellulose, in the sludge were converted into carbonaceous heavy metal absorbents using sulfur treatment, and its removal ability of lead from aqueous solution was examined. The sludge was treated with 5 M HCl to remove inorganic content, and then immersed in 1 M K₂S solution to prepare sulfur-immersed sludge. The immersed-sludge was heated at 100-1000 °C for 1 hour in nitrogen gas to produce the sulfur-impregnated adsorbent by pyrolysis. The product obtained at 400 °C (Product-400) has a high removal ability for lead ion, which has high specific surface areas and high sulfur content. The product-400 shows the highest adsorption of lead from aqueous solution, and high selective removal for lead ions in low pH solution.

γ-Polyglutamic acid (γ-PGA) has been reported to be an effective biosorbent for metal ions. In vitro binding of lead (II) (Pb) by γ-PGA produced from Bacillus subtilis NBRC16449 was examined and the effect of Pb and γ-PGA on Brassica chinensis L. grown in the laboratory was investigated. The results revealed that the optimal pH for Pb adsorption was 5.0. γ-PGA was stable at 35-50 °C and pH 5-7. The maximum removal efficiency was 87.9%. Brassica chinensis L. seeds were germinated and grown at 28±1 ^oC on filter paper soaked with Pb solution at 0, 50, 100 and 250 μM and γ-PGA at 0, 100, 500 and 1,000 mg/L for 7 days. The results indicated that Pb markedly inhibited growth of roots by reducing root length (P<0.05). However; the addition of 500 mg/L γ-PGA significantly protected seedlings from the adverse effects of Pb (P<0.05). Thus, γ-PGA has high potential as a biopolymer to be used for alleviation of Pb toxicities in plants.

Toxic organic substances are considered among the pollutants that have direct effect on humans and animals. Industrial wastewaters containing dissolved phenol can contaminate groundwater resources and thus lead to a serious groundwater pollution problem. In the present research, the adsorption technique for the efficient removal of phenol pollutants at trace level in water was employed. Four type of micro and nanocarbon materials including carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as nano carbon adsorbents, activated carbon (AC) and industrial carbon fly ash (CFA) as micro carbon adsorbents were used to remove phenol from water. Characterization of these adsorbents was performed by Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy(TEM), Thermogravimetric Analysis (TGA), BET specific surface area while the concentration of phenol in water before and after treatment was analyzed using UV-Spectroscopy. The pH (3-9) of the solution, was varied in order to determine their effect on the removal of phenol from water and hence on the adsorption rate.

Recovery of tantalum resource from used tantalum capacitor in electric equipment is important because the production of tantalum have not been stable for the price and the quantity. However, recovery of tantalum sintered compact from tantalum capacitor is difficult since the compact strongly covered with the flame retardant resin made of halogenated compounds (mold resin). In this study, steam gasification with sodium hydroxide was applied for recovery of tantalum sintered compact by destroying mold resin and stabilization of halogenated compounds in sodium hydroxide to prevent exhausting halogenated gas. Mold resin can be decomposed by steam gasification with NaOH to recover the sintered compact of tantalum. Furthermore, most halogen gas generated from decomposition of mold resin can be trapped in sodium hydroxide not to exhaust halogen gas. These results suggested that recovery process of tantalum sintered compact from the used condenser using steam gasification with sodium hydroxide is expected as a feasible way to recycle the rare metal in electric equipment.

This paper evaluated four waste limestones mined in the Minas Gerais State, Brazil, and its potential as soil acidity amendments and its effects upon soil fertility attributes. Laboratory and greenhouse experiments were performed at the University Centre of Formiga (UNIFOR), with Oxisols collected under native conditions. A randomly experimental design was set with four replications, five liming materials (four waste limestones products + a mix pure product, to comparison) applied in two liming rates (50% and 70% of base saturation), and a control plot (no lime applied). Each liming material was characterized with respect to CaO(%), MgO(%), and micronutrients Ca, Mg, Fe, Cu, Mn, Zn contents by atomic absorption spectrophotometer and the mineralogy by X-ray diffractometry. Results indicated that all liming materials tested could be classified as supplemental source of calcium and magnesium and caused an increase in soil pH, soil Ca and Mg, and base saturation levels, whereas aluminum saturation decreased. Dolomite, calcite and quartz are major minerals. Cu, Fe, Mn, and Zn were found in trace-amounts in all waste limestones, which was considered typical for such products. Considering the improvement of chemical characteristics and increase soil fertility, the use of waste limestone is an alternative that allows the use of commercial discarded material in small properties.

pH sensitive hydrogel particles were characterized for their rheological and swelling behaviour at various pH values specific to the gastrointestinal tract simulated conditions. Scanning electron microscopy was used to view the surface morphology of the hydrogels at different pHs. Swelling at pH 7.4 and shrinkage at pH 1.2 confirmed the pH sensitive behaviour of the hydrogel particles. The Linear Viscoelastic (LVE) range was determined by considering G’, one of the strain amplitude. Furthermore frequency sweep tests were performed in the LVE range where the storage modulus and loss modulus were determined at constant strain. It was observed that the loss modulus was higher at basic pH while the storage modulus was higher at lower pH. This rheological method can be used to explain the pH sensitive behaviour of hydrogels.

Critical depth is an important parameter in the design, operation and maintenance of open channels and analysis of gradually varied flow. For horseshoe cross section channels, the governing equations are highly nonlinear in the critical flow depth and thus solution of the implicit equations involves time consuming numerical methods. In current research, through conversion of critical depth equation to an objective function and then its minimization by using Particle Swarm Optimization algorithm, we calculate critical depth in horseshoe channels. The accuracy of the proposed model was also evaluated by comparing with existing equations. Furthermore this method can be used to deal with other optimization problems in hydraulic engineering.

Apoptosis in oocyte could be a good marker for oocyte quality and development competency. The study aims to investigate the relation between early apoptosis occurrence in different morphological groups of oocytes, i.e. Group A, B and C, and their developmental potential in terms of meiotic resumption to metaphase II. Annexin-V staining was used to detect early apoptosis in oocytes and Giemsa staining for meiotic resumption. Immature oocytes in Group B and C showed significantly high incidence of early apoptosis compared to Group A oocytes (A: 10.20%, B: 19.00% and C: 20.60%). After maturation, no differences were observed in the incidence of early apoptosis among oocytes from different groups (A: 28.40%, B: 18.20% and C: 23.00%). However, the mean percentage of early apoptosis increased among Group A oocytes after maturation. The progression to metaphase II were similar among the different groups of oocytes (A: 34.09%, B: 31.54% and C: 33.45%). In conclusion, early apoptosis occurrence in bovine oocytes is related to developmental competence.

Recently, it has been argued that, contrary to earlier energy ladder thinking, households in developing countries do not switch to modern energy sources but instead tend to consume a combination of fuels. This article aimed to gather a better understanding of the relative importance of fuel substitution and fuel complementation, especially among charcoal, fuel briquettes and kerosene, and the factors associated with these choices. In this paper we present results of a household survey conducted during October 2010 in Kibera slums in Nairobi, Kenya. The results revealed that widely various household characteristics influence demand for charcoal and briquettes for cooking. In addition to these factors, the household income level affects the use of kerosene for cooking. At the same time, we found the fact households tend to switch to multiple fuels strategy as their increasing in income instead of completely switching from the consumption of traditional fuels to modern energy sources.