Influence Of Colloids Research Articles

Influence of a novel nano-thermite colloid based on CuO coated CNTs on the thermo-analytical characteristics of 1,3,5-trinitro-1,3,5-triazinane

ABSTRACT Nano-thermite colloid is a promising field of research used to enhance the characteristics of energetic materials. In this study, pre-treated surfaces of multiwall-carbon nanotubes (MWCNTs) were catalyzed to help the deposition of a metal and the coating process by copper (Cu) nano-scale layer through electroless deposition. The formed hybrids coated by Cu were treated at 250°C to form MWCNTs coated by CuO. Acetone was used to suspend the coated MWCNTs with aluminum nanoparticles (120 nm) in order to form nano-thermite colloid by ultrasonic technique. The presence of CuO layer plays the role of an active oxidizer for the aluminum nanoparticles. The obtained colloid was incorporated and dispersed with 1,3,5-trinitro-1,3,5-triazinane (RDX). The influence of colloid on RDX decomposition kinetic was evaluated using the isoconversional methods (modified Kissinger-Akahira-Sunose (KAS) methods). The mean value of apparent activation energy was reduced by 37.5%. This dramatic change in RDX decomposition ascribed trait to the nano-thermite colloid high reactivity and the facile integration of colloidal thermite particles with the RDX.

Influence of colloids and colloids’ coagulation on selenite sorption

Colloids play a crucial role in the sorption and migration of contaminants in the environment，while up to today, limited information exists about the influence of bentonite colloids on the sorption of selenite due to the weak sorption capacity of bentonite colloids to anions. Since bentonite will be used as backfilling materials in granite hosted repositories, and colloids would be generated when bentonite contacts with groundwater, the investigation of the sorption of selenite onto bentonite colloids and the effects of colloids coagulation on the sorption of selenite onto the colloids are badly needed. In this work, the distribution of selenite in the bentonite/deionized (DI) water system and the influence of Beishan (potential granite-hosted geologic repository of China) groundwater on the distribution are investigated. The results show that in the bentonite/DI water system, about 40% of the selenite is adsorbed onto the colloids at pH~5. Selenite sorption onto colloids reaches maximum at pH~5 as a result of the synergy effects of charge of the edge sites and size of the colloids. However, high concentration of colloids cannot be generated or stable in Beishan groundwater. When the bentonite colloids coagulate, the sorption sites of the colloids for selenite decrease, which leads to selenite sorption decreasing. When the colloids bearing selenite coagulate, most of the selenite adsorbed onto the colloids would be released into the solution, and the sorption of selenite onto the colloids at pH~5 decreases from 70% to 10−20%. Selenite sorption onto coagulated colloids is mainly controlled by the surface complex of selenite and divalent cations in the system, which is different from that onto bentonite colloids (controlled by inner-complexation).

Colloidal Influence Factor of Bioflocculant in Coagulation of Chromium and Nitrobenzene

The aim of this study is to investigate the flocculation capacity of activated sludge flocculant in chromium ion and nitrobenzene solutions. Besides comparing with activated carbon, we changed some potential factors which may influence the flocculation, such as solution pH value, reaction time, flocculant dosage, and solution initial concentration, and tested the flocculation capacity of this bioflocculant for both chromium and nitrobenzene. In addition, the flocculation of activated sludge after acidic or alkali modification for double solutions was also estimated. Compared with activated carbon, the activated sludge flocculant showed a good flocculation capacity for nitrobenzene, but poor flocculation for chromium following the initial concentration increase. The flocculation for nitrobenzene or chromium increased at initial stage and decreased gradually following the primary dosage of flocculant increase. The flocculation for nitrobenzene increased at the primary stage and decreased after peak, while the flocculation for chromium increased following the pH increase of both solutions. Although the flocculation for nitrobenzene decreased, the flocculation for chromium increased obviously, when we prolonged the reaction time. The flocculant showed a gradual increasing trend in double kinds of solution when they were heating. The flocculation for both nitrobenzene and chromium decreased after acid modification of activated sludge flocculant, while the flocculation increased after basic modification. The present research provided further theoretical basis of the biosorption of heavy metal waste water and nitrobenzene organic toxicants.

Neptunium(V) transport in granitic rock: A laboratory scale study on the influence of bentonite colloids

In the present study neptunium(V) uptake by crystalline granitic rock (Kuru Grey granite) and the role of stable and mobile bentonite colloids (MX-80) on the migration of neptunium(V) was investigated. Two different experimental setups were utilized, batch-type experiments under stagnant conditions and column experiments under flowing water conditions. The uptake of 10−6 M neptunium(V) by 40 g/L crushed granite in 10 mM NaClO4 was found to be pH-dependent, whereas neptunium(V) uptake by MX-80 bentonite colloids (0.08–0.8 g/L) was pH-independent up to a pH-value of approximately 11. Column experiments were conducted in the presence and absence of colloids at two pH values (pH = 8 and 10) and two flow rates (0.3 and 0.8 mL/h) in 10 mM NaClO4. The injected neptunium(V) concentration was 2 × 10−4 M and the colloid concentration ranged from 0.08 to 0.32 g/L. The properties of the flow field in the columns were investigated with a conservative chloride tracer, at the same two flow rates of 0.8 and 0.3 mL/h. The resulting breakthrough curves were modeled using the analytical solution of advection–matrix diffusion equation. A tailing of neptunium(V) breakthrough curves in comparison to the conservative tracer was observed, which could be explained by a slightly higher retardation of neptunium(V) in the column caused by sorption on the granite. The sorption was in general lower at pH 8 than at pH 10. In addition, the tailing was almost identical in the absence and presence of MX-80 bentonite colloids, implying that the influence of colloids on the neptunium(V) mobility is almost negligible.

Influence of colloid and adsorption parameters on contaminant transport in fractured rocks - A triple continuum model

Contaminant transport in fractured formations is strongly affected by the presence of fracture skin in the rock matrix. A triple continuum solute transport model is developed, incorporating the fracture skin as the third continuum, besides the fracture and the rock matrix, to describe the colloid facilitated contaminant transport in fractured formations. Sorption of the contaminant onto suspended and deposited colloids is assumed to follow a modified Freundlich reversible equilibrium isotherm. The resulting set of governing partial differential equations is solved using a fully implicit finite difference method. The distribution coefficient for contaminant sorption onto the deposited colloids and isotherm fitting parameter for contaminant sorption onto the deposited colloids are shown to be the most critical colloid related parameter affecting the contaminant transport in fractured media in presence of colloids. Furthermore, it is demonstrated that contaminant migration in fractured media is greatly affected by the presence of previously deposited colloids on fracture surfaces.

Influence of colloids on the attenuation and transport of phosphorus in alluvial gravel aquifer and vadose zone media

Phosphorous (P) leaching (e.g., from effluents, fertilizers) and transport in highly permeable subsurface media can be an important pathway that contributes to eutrophication of receiving surface waters as groundwater recharges the base-flow of surface waters. Here we investigated attenuation and transport of orthophosphate-P in gravel aquifer and vadose zone media in the presence and absence of model colloids (Escherichia coli, kaolinite, goethite). Experiments were conducted using repacked aquifer media in a large column (2m long, 0.19m in diameter) and intact cores (0.4m long, 0.24m in diameter) of vadose zone media under typical field flow rates. In the absence of the model colloids, P was readily traveled through the aquifer media with little attenuation (up to 100% recovery) and retardation, and P adsorption was highly reversible. Conversely, addition of the model colloids generally resulted in reduced P concentration and mass recovery (down to 28% recovery), and increased retardation and adsorption irreversibility in both aquifer and vadose zone media. The degree of colloid-assisted P attenuation was most significant in the presence of fine material and Fe-containing colloids at low flow rate but was least significant in the presence of coarse gravels and E. coli at high flow rate. Based on the experimental results, setback distances of 49–53m were estimated to allow a reduction of P concentrations in groundwater to acceptable levels in the receiving water. These estimates were consistent with field observations in the same aquifer media. Colloid-assisted P attenuation can be utilized to develop mitigation strategies to better manage effluent applications in gravelly soils. To efficiently retain P within soil matrix and reduce P leaching to groundwater, it is recommended to select soils that are rich in iron oxides, to periodically disturb soil preferential flow paths by tillage, and to apply a low irrigation rate.

The influence of colloids on the geochemical behavior of metals in polluted water using as an example Yongdingxin River, Tianjin, China

The role of colloids in estuarine and marine systems has been studied extensively in recent years, whereas less is known about the polluted freshwater system. Yongdingxin River is one of the major recipients of industrial effluents in Tianjin. This article evaluates the role of colloids in controlling geochemical behavior of Cu, Zn, Fe, Mn, Hg and Cr at the confluences between Yongdingxin River and its major tributaries Beijing Drainage River, Jinzhong River and Beitang Drainage River. Based on the distribution of metal partitioning among particulate (>0.22 μm), colloidal (1 kDa to 0.22 μm) and truly dissolved (<1 kDa) fractions, the metals can be assigned to the following groups: Group 1 – organic colloidal pool-borne elements Cu and Cr; Group 2 – inorganic colloidal pool-borne metals Fe and Mn; Group 3 – Zn and Hg characterized by varying complexation patterns. The distribution of metal partitioning among particulate, colloidal and truly dissolved fractions was influenced by anthropogenic input. In addition, the theoretical concentrations of elements in case of conservative mixing between the waters of Yongdingxin River and the waters of its tributaries were compared with the measured values to evaluate the geochemical role of colloids. The result showed that all of the metals presented a non-conservative mixing behavior. Addition of colloids resulted in the removal of metals from the water column to bed sediment during river water mixing, which was furthermore confirmed by the similar partition coefficient of metal concentration between colloid and sediment.

Use of a column leaching test to study the mobility of chlorinated HOCs from a contaminated soil and the distribution of compounds between soluble and colloid phases

An equilibrium and recirculation column test for hydrophobic organic chemicals (ER-H test) was used to study the leaching behaviour of chlorophenols (CPs), polychlorinated diphenyl ethers (PCDEs), polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo- p-dioxins (PCDDs) from contaminated soil. A 50% increase in the pore water velocity was shown to have little or no effect on the mobility of CPs, PCDEs, PCDFs and PCDDs. The standard deviations of truly dissolved compounds, CPs, were between 19% and 65% between the tests. However, the repeatability of the ER-H test decreased with increases in the hydrophobicity of the studied compounds; the standard deviations for PCDEs, PCDFs and PCDDs ranged from 53% to 110%, 57% to 77% and 110% to 130%, respectively. The influence of colloids on the release of these compounds was also examined. Up to 30% of the CPs in the soil were leached, of which 1–3% were associated with colloids. The PCDEs, PCDFs and PCDDs were found to be preferably associated with the particulate fraction of the leachate, and less than 0.2% of these compounds were mobilised.

Analytical modeling for colloid-facilitated transport of N-member radionuclides chains in the fractured rock

A previous analytical model for N-member radionuclide decay chains has been extended to include the effect of radionuclide sorption with groundwater colloids. Published distribution coefficients were employed in the nuclide decay chain to illustrate the present model. The colloid concentration was assumed constant in time and space owing to equilibrium between colloid generation and sedimentation by chemical and/or physical perturbations. Furthermore, the diffusion of colloids into the rock matrix was ignored because the diameter of colloid is relatively large and colloids and fracture surfaces are like-charged. The results indicated that colloids could facilitate the transport of radionuclides and the large adsorbability of nuclides with colloids enlarged the effect of acceleration by colloids. The influence of colloids on the radionuclide transport was expected to be crucial to the actinides with large adsorbability; however, the present results revealed that the low-adsorbing nuclides whose parent nuclides have large capability of sorption could be also facilitated significantly by colloids indirectly. Therefore, the role of colloids played in the transport of the radionuclides decay chain should be assessed carefully in the radioactive waste disposal. The analytical method presented herein is helpful to verify/validate further complex far-field models.

Influence of colloids on uranium transport in nuclear waste repositories and abandoned uranium mines—A critical comparison

Influence of colloids on uranium transport in nuclear waste repositories and abandoned uranium mines—A critical comparison

Approach to Assessing the Potential Effects of Colloidal Radionuclide Transport on Nuclear Waste Repository Performance

The U.S. Nuclear Regulatory Commission (NRC) is independently evaluating technical issues such as colloid-facilitated radionuclide transport in preparation for reviewing an anticipated license application from the U.S. Department of Energy (DOE) for a potential high-level nuclear waste repository at Yucca Mountain, Nevada. For performance assessment computer simulations of evolving conditions many years into the future, the influence of colloids in enhancing radionuclide transport is difficult to estimate and highly uncertain. NRC staff is conducting a multipronged approach to assessing whether or not these uncertainties are sufficiently represented by performance assessment models. Preliminary simplified calculations providing a conservative estimate of calculated dose from colloidal Pu suggest that an effect on dose is plausible. A more sophisticated effort involves analytical modeling of colloidal Pu transport that uses laboratory and field data to represent more accurately processes such as kinetic controls on sorption (attachment) and desorption (detachment) of radionuclides at colloid surfaces. This modeling effort shows that slow desorption of radionuclides from colloids is a factor that could enhance radionuclide migration. Finally, an abstraction of colloidal transport is being implemented in the NRC total-system performance assessment model in order to integrate potential colloidal effects at the system level. This implementation is flexible enough that a variety of sensitivity studies can be conducted that will aid identification of the model parameters most significant to transport.

Influence of colloid, preservation medium and trimetazidine on renal medulla injury.

In organ transplantation, preservation injury is an important factor which could influence short-term and long-term graft outcome. The renal medulla is particularly sensitive to oxidant stress and ischemia-reperfusion injury (IRI). Using an autotransplant pig kidney model, we investigated renal function and medullary damage determined between day 1 and week 2 after 24- or 48-h cold storage in different preservation solutions: University of Wisconsin solution (UW), Hopital Edouard Herriot solution (a high Na+ version of UW), ECPEG (high Na+ preservation solution with PEG) and ICPEG (a high K+ version of ECPEG) with or without trimetazidine (TMZ). TMZ improved renal preservation and increased renal function when added in each preservation solution (particularly HEH and ECPEG). Medullary damage led to the early appearance of trimethylamine-N-oxide (TMAO) followed by 1H-NMR in urine and plasma. TMZ and ECPEG is the most efficient association to reduce medullary damage. This study clarifies the role of colloid and polarity solution and the role of mitochondrial protection by TMZ.

Colloid’s influences on microalgae growth as a potential environmental factor

The role of colloid as “colloid pump” in the ocean is well known. The important influence of colloid in seawater on the growth of microalga was found in our 1999–2000 study. Colloid concentrates were obtained by employing a cross-flow filtration system to ultrafilter seawater (which had been pre-filtrated by 0.45 μm acetate cellulose membrane) successively with different membranes. Ultrafiltration retentions (we called them colloid concentrates) together with control sample (seawater without colloid) were then inoculated with two species of microalgae and cultivated in selected conditions. Monitoring of microalgae growth during cultivation showed that all colloid concentrates had obvious influence on the growth of the microalgae studied. Addition of Fe(OH)3 colloid or organic colloid (protein or carbohydrate) to the control sample enhanced the microalgae’s growth.

放射性廃棄物地層処分の核種移行評価におけるコロイドの影響

放射性廃棄物地層処分の安全性評価のためには，地層処分環境下での核種移行に及ぼすコロイドの影響を評価することが必要である．本稿では，放射性廃棄物処分系におけるコロイドの生成，核種移行に及ぼすコロイドの影響，移行モデルに関して近年の研究をまとめた．核種コロイドは放射性廃棄物の溶出液に含有されるが，ベントナイト系緩衝材で移行を抑制することができる，核種移行に及ぼすフミン，微生物のコロイドの影響についても評価が必要であり，有機物，微生物および核種の相互作用に関する研究が課題である．ベントナイトおよびセメントからのコロイドの生成についても検討されたが，核種移行において議論するためにはデータが不十分である．コロイドが共存する場合の核種移行を予測するためには，核種－コロイド－岩盤の3相間の平衡に関するモデル化が重要である．

Speciation of Solutes in Drainage and Pore Waters of Two Former Lignite Mines (Germany)

An experimental speciation scheme consisting of ultra-filtration(1 kD), cation and anion exchange has been developed. Parallel calculations of the ion balances are performed using the computerroutine MINTEQA2. The experimental and computed ion balances suffer from non-equilibrium conditions, incalculability of metal-binding colloids or sub-colloids, inaccurate Eh measurements and analytical errors. In most samples colloidal or sub-colloidal structures of Fe oxy-hydroxides and/or gypsum influence the behavior of many trace elements. The comparison of theory and experiment has to be restricted to acid waters (pH < 5) where colloids (≥1–450 nm) and non-filterable colloids or sub-colloids (<1 nm) play a minor role. Yet, only a few transition metals such as Mn, Fe, Co, Ni, Cu, Zn, or Cd remain more or less free of colloidal influence in low pH waters. The effect of DOC on Al may be estimated by model substances like citrate.

Soil phosphorus fractions in solution: influence of fertiliser and manure, filtration and method of determination

This study investigated the forms of soil P released to solution, accuracy of their determination, and influence of colloids on P sorption/desorption dynamics. A Hagerstown silt loam, amended with dairy and poultry manure or superphosphate at five rates (0, 25, 50, 100, and 200 kg P ha −1) , was extracted at two soil:solution ratios (1:5 and 1:100) and filtered at three pore sizes (0.8, 0.45, and 0.22 μm). Results showed that relative to the proportion of dissolved organic P (DOP, determined as the difference between total dissolved P [TDP] and P detected by ion chromatography), DRP increased with amendment rate. Relative to Mehlich-3 extractable P, DRP exhibited a power relationship with a much greater potential for soil P release at concentrations in excess of ca. 50 mg Mehlich- 3 P kg −1 . Concentrations of DRP, determined by the acid molybdate method, were on average 12.5% greater than P detected by ion chromatography indicating P was solubilised during colorimetric determination. A linear relationship was found between total Al and DRP, which could indicate acid mediated hydrolysis of Al–humic–P substances, although acid mediated desorption of P from colloids cannot be discounted. No difference in solubilised P was found between solutions filtered at 0.22 and 0.45 μm, but was found between 0.8 μm and smaller filter sizes. Organic P extracted from manured soils was more recalcitrant than that extracted from soils amended with superphosphate, the later attributed to its accumulation in more labile pools. The sorption/desorption of P by colloids in solution were greatly affected by the rate of amendment and the soil:solution extraction ratio. More P was sorbed by superphosphate solutions compared to dairy manure amended soil solutions and was attributed to the saturation of colloidal P sorption sites by organic matter. In order to minimise the effects of colloids on P dynamics and the potential for hydrolysis in solution, filtration to at least 0.45 μm is required. However, soils with a lesser aggregate stability may require additional filtration.

Plasma fibronectin and complement following infusion of colloidal solutions after spinal anaesthesia

A randomized study of 30 patients undergoing uncomplicated surgery under spinal anesthesia was conducted to assess the influence of colloids on the kinetics of plasma fibronectin and complement. Both are opsonins of the reticuloendothelial system; moreover fibronectin is concerned with host resistance against septic complications following trauma and surgery. The patients were assigned to receive either Ringer's lactate (Group 1), gelatin (Group 2) or dextran 40 (Group 3). Blood samples were withdrawn before colloids or Ringer's infusion and during the 4 postoperative days. There was a reduction in plasma fibronectin throughout the study in groups 1 and 3, but an increase in group 2 by 24 h. The adhesion of plasma fibronectin to gelatin was maximal 1 h after infusion (44%) and remained significant up to day 2 in group 2. There was no relationship in groups 1 and 3. C3 and C4 components of complement exhibited a low value in the early post-operative period, due to hemodilution. This study shows an in vivo fibronectin-gelatin interaction, and suggests that gelatin infusion inhibits the increased shift of plasma fibronectin at the site of tissue injury after surgery.

Study of humic organic substances and heavy metals in the ivankovo reservoir waters

The Ivankovo Reservoir is the main source of water supply of Moscow. Its waters are intensively coloured. Correlations between colour values and humic and fulvic acids content in waters, as well as the influence of colloid and dissolved forms of humic substances on heavy metal migration in the reservoir are studied. A scheme of experimental fractioning of chemical components occurring in water is suggested. A method of atomic emission spectrometry is suggested for the determination of heavy metals in every fraction.

The Migration Behaviour of Transuranium Elements in Gorleben Aquifer Systems: Colloid Generation and Retention Process

ABSTRACTThe colloid generation as a part of the migration process of trans-uranic ions has been studied in the Gorlben aquifer system. From the migration study for the Gorleben repository site, typical examples are selected to demonstrate the influence of colloids. The quantification of colloid generation and its influence on the dissolution and geochemical sorption of transuranium elements are discussed.

Influence of colloids on sediment-water partition coefficients of polychlorobiphenyl congeners in natural waters

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of colloids on sediment-water partition coefficients of polychlorobiphenyl congeners in natural watersJoel E. Baker, Paul D. Capel, and Steven J. EisenreichCite this: Environ. Sci. Technol. 1986, 20, 11, 1136–1143Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 1986https://doi.org/10.1021/es00153a009RIGHTS & PERMISSIONSArticle Views348Altmetric-Citations170LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (862 KB) Get e-Alerts Get e-Alerts