This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 w...This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method, and characterized by XRD, XPS, TEM, UV-Vis and photoluminescence (PL). It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7. And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method. This was mainly due to their high value in highly-dispersed platinum oxides (PtOx) content on the surface of the catalysts. The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7. And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method. And in the zeta potential study, the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5, which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.展开更多
Heavy hydrocarbons (HHCs) in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated wi...Heavy hydrocarbons (HHCs) in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A (UVA) or ultraviolet radiation C (UVC) activated titanium dioxide (TiO2) (1%-5%) under varying moisture conditions (0%- 300% water holding capacity (WHC)) to enhance biodegradation of HCCs and shorten remediation time- frames. We demonstrate that pretreatment of impacted soils with UVC-activated TiO2 in soil slurries could enhance bioremediation of HHCs. Total petroleum hydrocarbon (TPH) removal after 24 h exposure to UVC (254 nm and 4.8 mW/cm2) was (19.15:1.6)% in slurries with 300% WHC and 5 wt-% TiO2. TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO2 concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to (26.05:0.9)%, compared to (15.45:0.8)% for controls without photo- catalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO2 to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO2. This suggests that activation of TiO2 by sunlight and direct addition of TiO2 to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA (7.5 mW/cm2) or UVC (1.4 mW/cm2) penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO2 to enhance soil bioremediation under land farming conditions.展开更多
Aim of the present study was to synthesize titanium dioxide nanoparticles (YiO2 NPs) from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates wer...Aim of the present study was to synthesize titanium dioxide nanoparticles (YiO2 NPs) from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI'-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 (AR-79) and Acid Red 80 (AR-80). Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.展开更多
During financial crisis,companies constantly need free cash flows to efficiently react to any uncertainty,thus ensuring solvency.Working capital requirement(WCR)has been recognized as a key factor for releasing tied u...During financial crisis,companies constantly need free cash flows to efficiently react to any uncertainty,thus ensuring solvency.Working capital requirement(WCR)has been recognized as a key factor for releasing tied up cash in companies.However,in literatures related to lot-sizing problem,WCR has only been studied in the single-level supply chain context.In this paper,we initially adopt WCR model for a multi-level case.A two-level(supplier–customer)model is established on the basis of the classic multi-level lot-sizing model integrated with WCR financing cost.To tackle this problem,we propose sequential and centralized approaches to solve the two-level case with a serial chain structure.The ZIO(Zero Inventory Ordering)property is further confirmed valid in both cases.This property allows us to establish a dynamic programming-based algorithm,which solves the problem in O(T).Finally,numerical tests show differences in optimal plans obtained by both approaches and the influence of varying delays in payment on the WCR of both actors.展开更多
基金supported by the National Natural Science Foundation of China (No. 50908201)
文摘This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method, and characterized by XRD, XPS, TEM, UV-Vis and photoluminescence (PL). It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7. And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method. This was mainly due to their high value in highly-dispersed platinum oxides (PtOx) content on the surface of the catalysts. The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7. And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method. And in the zeta potential study, the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5, which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.
文摘Heavy hydrocarbons (HHCs) in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A (UVA) or ultraviolet radiation C (UVC) activated titanium dioxide (TiO2) (1%-5%) under varying moisture conditions (0%- 300% water holding capacity (WHC)) to enhance biodegradation of HCCs and shorten remediation time- frames. We demonstrate that pretreatment of impacted soils with UVC-activated TiO2 in soil slurries could enhance bioremediation of HHCs. Total petroleum hydrocarbon (TPH) removal after 24 h exposure to UVC (254 nm and 4.8 mW/cm2) was (19.15:1.6)% in slurries with 300% WHC and 5 wt-% TiO2. TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO2 concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to (26.05:0.9)%, compared to (15.45:0.8)% for controls without photo- catalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO2 to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO2. This suggests that activation of TiO2 by sunlight and direct addition of TiO2 to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA (7.5 mW/cm2) or UVC (1.4 mW/cm2) penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO2 to enhance soil bioremediation under land farming conditions.
基金VIT University,Vellore,and TamilnaduIndia for supporting this study
文摘Aim of the present study was to synthesize titanium dioxide nanoparticles (YiO2 NPs) from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI'-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 (AR-79) and Acid Red 80 (AR-80). Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.
基金This work is supported by the Ministry of Science and Technology of China(Grant No.2016YFC0503606)the National Natural Science Foundation of China for Distinguished Young Scholar(Grant No.71825007)ANR FILEAS FOG project.
文摘During financial crisis,companies constantly need free cash flows to efficiently react to any uncertainty,thus ensuring solvency.Working capital requirement(WCR)has been recognized as a key factor for releasing tied up cash in companies.However,in literatures related to lot-sizing problem,WCR has only been studied in the single-level supply chain context.In this paper,we initially adopt WCR model for a multi-level case.A two-level(supplier–customer)model is established on the basis of the classic multi-level lot-sizing model integrated with WCR financing cost.To tackle this problem,we propose sequential and centralized approaches to solve the two-level case with a serial chain structure.The ZIO(Zero Inventory Ordering)property is further confirmed valid in both cases.This property allows us to establish a dynamic programming-based algorithm,which solves the problem in O(T).Finally,numerical tests show differences in optimal plans obtained by both approaches and the influence of varying delays in payment on the WCR of both actors.