检索结果-南通市图书馆

New Jo.rnal o. Glass and Ceramics 2020年第2期10卷 15-27页

作者： jude o. ighere P. Alex Greaney Scho.l o. Mechanical Industrial & Manufacturing Engineering Oregon State University Corvallis OR USA

Thermal sto.age po.ential and thermal expansio. are characteristic pro.erties fo. extreme applicatio.s. ZrB2 is a candidate fo. advanced applicatio.s in aircraft and fusio. reacto.s. This article presents density functio.al theo.y calculatio.s o. its states, micro.tructure and quasi-harmo.ic levels calculatio.s o. thermo.hysical pro.erties. Band structure highlighted dynamical instability with metallic impurities in ZrB2 structure based o. frequency mo.es. The o.served pro.ected density o. states (PDo.) appro.riate 4d o.bital o. Zr do.inated at lo. frequency bo.h in perfect crystal in the presence o. absence o. co.alent impurities while B 2s and 2p o.bitals do.inate higher frequency states. Temperature dependency and aniso.ro.y o. co.fficient o. thermal expansio. (CTE) were evaluated with vario.s impurities. Vario.s thermo.ynamic pro.erties like entro.y and free energy were explo.ed fo. degrees o. freedo. resulting fro. internal energy changes in the material. Co.puted results fo. heat capacity and CTE were co.pared to.available numerical and experimental data.

关键词： Zirco.ium Dibo.ide ZrB2 Thermal Expansio. Defects Mo.ecular Dynamics Specific Heat Capacity

Co.tro.led-Release Analysis o. Po.assium Permanganate Using PMMA Matrix

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Jo.rnal o. Minerals and Materials Characterizatio. and Engineering 2014年第6期2卷 539-544页

作者： jude o. ighere Ramesh C. Chawla Chemical Engineering Department Howard University Washington DC USA

Excess amo.nt o. po.assium permanganate has o.ten been used in-situ fo. chemical o.idatio. o. co.taminated sites. The co.sequences are no. limited to.seco.dary co.taminatio. and co.t but also.inefficient remediatio.. Encapsulatio. o. permanganate using PMMA enables co.tro.led disso.utio. o. the o.idant and aids lo.g-term pro.esses. This paper fo.uses o. the o.idant release efficiency fro. po.ymer matrix and analysis o. data using existing mo.els fo. glassy po.ymers. The efficiency pro.ile o.tained using mass ratio. o. 2:1, 4:1, and 8:1 o. PMMA to.KMno. sho.ed a decrease in the extent o. release with increasing mass ratio.with 79%, 55.35% and 33.59% respectively. Patches were no.iced o. the surfaces o. PMMA after the release o. KMno., these were attributed to.crevices created by the no.-fickian diffusio. o. the o.idant.

关键词： PMMA Co.tro.led-Release Permanganate Analysis Encapsulatio.

Applicatio.s o. Po.assium Permanganate in the o.idative Degradatio. o. Trichlo.o.thylene

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Jo.rnal o. Materials Science and Chemical Engineering 2015年第7期3卷 16-27页

作者： jude o. ighere Karina Ho.jo.a Ramesh C. Chawla Chemical Engineering Howard University Washington DC USA

The sco.e o. this study was to.determine techniques to.remediate trichlo.o.thylene co.taminatio. under different enviro.mental co.ditio.s, media and in co.existence with chro.ium. The specific o.jectives were fo.used o. the o.idatio. o. trichlo.o.thylene (TCE) in so.l and aqueo.s media using bo.h unmo.ified KMno. particles and po.y (methyl methacrylate), PMMA encapsulated KMno. in the presence and absence o. hexavalent chro.ium, Cr(VI). Mo.ar ratio. (p-values) o. KMno. to.TCE were used as a determining facto. in the TCE o.idatio. pro.ess. p-values o. 2, 5 and 10 were investigated in aqueo.s media and an appro.imately 0.5 M-1·s-1 rate co.stant was o.tained using unmo.ified KMno. in aqueo.s system. The extent o. o.idatio. did no. change with TCE co.centratio.. In so.l system, TCE o.idatio. requires a large amo.nt o. KMno. to.pro.uce similar results as in aqueo.s system. pH experiments indicate that except at high alkaline co.ditio., pH do.s no. impact the extent o. TCE o.idatio.. Also. the presence o. Cr(VI) did no. hinder TCE o.idatio. by KMno.. Using co.tro.led release applicatio., the rate o. TCE o.idatio. was reduced by PMMA encapsulated KMno.. Co.parative study indicated an expectedly slo. rate o. TCE degradatio. using mo.ified KMno. but similar o.erall extent o. o.idatio. fo. bo.h mo.ified and unmo.ified KMno.. The applicatio. o. the encapsulated matrix yielded 88% ± 3% TCE o.idatio. and a simultaneo.s 81% ± 2.1% Cr(VI) reductio. by ferro.s io. in the same system.

关键词： Trichlo.o.thylene Kinetics Permanganate o.idatio. Po.y Methyl Methacrylate Mixed Co.taminants

Using Ferro.s Io. fo. the Reductive Degradatio. o. Hexavalent Chro.ium

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Chemical Engineering and Science 2015年第1期5卷 15-22页

作者： jude o. ighere Karina Ho.jo.a Ramesh C. Chawla Chemical Engineering Department Howard University Washington DC USA

This paper discusses the to.icity and mo.ility o. chro.ium species. And it presents the extent and kinetics o. reductive remediatio. o. hexavalent chro.ium, Cr+ using ferro.s io., Fe2+. Mo.ar ratio. o. 1:3 and 1:6 o. Cr (VI) to.Fe (II) were used. Integral metho. o. data analysis sho.ed reactio. fo.lo.ed seco.d-o.der kinetics with R square values near unity. Reactio. was initially fast but with a rapid precipitatio. attributed to.Cr (III)-Fe (III) in previo.s studies. This co.lo.dal precipitate ultimately sto.s the reactio., which explains while co.versio. efficiency increases with increased mo.ar ratio.o. Cr (VI) to.Fe (II). The impact o. pH was investigated by adjusting the Cr (VI)-Fe (II) medium to.pH 2.78, 5.24, 7.00, 9.00 and 11.96 using predetermined dro.s o. acid o. base. Reactio. was mo.e rapid under alkaline co.ditio.s with higher extent o. degradatio. co.sistent with previo.s research. In so.l system, mass transfer limitatio. was hardly no.iced as high extent o. reductio. was reco.ded relative to.aqueo.s phase. The high so.ubility o. Cr (VI) aided the release into.the aqueo.s media fo. reductio. by ferro.s sulfate.

关键词： Reductio. Hexavalent Trivalent Chro.ium Remediatio. Degradatio. Ferro.s Io. Kinetics