Investigation of the effect of diethylene triamine pentaacetic acid chelating agent as an enhanced oil recovery fluid on wettability alteration of sandstone rocks

This study used the diethylene triamine pentaacetic acid(DTPA)-seawater(SW)system to modify the sandstone rock wettability and enhance oil recovery.The investigation involved conducting wettability measurement,Zeta potential measurement,and spontaneous imbibition experiment.The introduction of 5%DTPA-sW solution resulted in a significant decrease in the rock-oil contact angle from 143°to 23,along with a reduction in the Zeta potential from-2.29 mV to-13.06 mV,thereby altering the rock surface charge and shifting its wettability from an oil-wet state to a strongly water-wet state.The presence or absence of potential determining ions(Ca^(2+),Mg^(2+),SO_(4)^(2-))in the solution did not impact the effectiveness of DTPA in changing the rock wettability.However,by tripling the concentration of these ions in the solution,the performance of 5%DTPA-SW solution in changing wettability was impaired.Additionally,spontaneous imbibition tests demonstrated that the 5%DTPA-SW solution led to an increase in oil recovery up to 39.6%.Thus,the optimum mass fraction of DTPA for changing sandstone wettability was determined to be5%.

The effect of chelating agent on hydrodesulfurization reaction of ordered mesoporous alumina supported Ni Mo catalysts

In this paper,ordered mesoporous alumina(OMA)support with the high surface area(328 m^(2)g^(-1))and the large pore volume 0.74(cm^(3)·g^(-1))was synthesized by homogeneous precipitation method.And the influence of EDTA on the physical and chemical properties of the modified catalysts was also studied.The characteristic results showed that the addition of EDTA could adjust the metal-support interaction and improved the acidity of the corresponding catalyst.Combined with the catalytic performance results,the EDTA-modified Ni Mo E(1.0)/OMA catalyst displays the highest DBT hydrodesulfurization conversion(97.7%).

Influence of Different Chelating Agents on Corrosion Performance of Microstructured Hydroxyapatite Coatings on AZ91D Magnesium Alloy

To improve the bioactivity and corrosion resistance of AZ91 D magnesium alloy,hydroxyapatite（HAp） coatings with novel microstructured morphologies were prepared successfully on AZ91 D substrates via a facile hydrothermal method.Different chelating agents including polyaspartic acid（PASP） and ethylenediaminetetraacetic acid（EDTA） were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys.The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres,while the coating prepared with EDTA consisted of many flower-like particles.Moreover,the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP.Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating.Immersion test of the coated samples in simulated body fluid（SBF） demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.

SYNERGISTIC ACTIVATION OF CHELATING AGENT ON XANTHATE DURING THE FLOTATION OF REFRACTORY COPPER OXIDIZED ORES

For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and its adsorption characteristics ivere studied in the flotation of malachite and chrysocolla representatively selected by means of XPS,IR, absorbed quanti-ty measurements and flotation tests.For easily-dissolved malachite flotation , a small amount of chelating agent can obviously enhance xanthate collecting power and make malachite floated easily , and so reduces the consumption of xanthate. For hard-dis-晄olved chrysocolla, chelating agent is able to increase its recovery to 90% , but the chelating agent consumption is high. Chelating agent and xanthate can produce synergistic adsorptions, which follmv Freundlich's adsorption equation on malachite and Chrysocolla surfaces. The high chemical activity of chelating agent and its synergistic activation on xanthate are the key to improving xanthate collection poiver. The synergistic activation of chelat-ing agent on xanthate on melachite surfaces is clearly stronger than on chrysocolla surfaces. According to experimental results, it can be thought that the synergistic activation results from the synergistic complexation of chelating agent and xanthate with copper ions to form biligand-tribasic co-ordination complex.

IMPROVEMENT OF BLEACHING OF KAOLIN USING CHELATING AGENTS

Bleaching of the kaolin ore from Shaziling Kaolin Mine in Jiangxi Province of China was studied with the aim of enhancing the quality and value of the ore to meet the requirements from the ceramics manufacturers. Factors affecting the reductive bleaching of kaolin ore with sodium dithionite as the bleaching agent were studied and optimized to increase the whiteness of the kaolin ore from 38. 5% to about 65%. However, it was found that in the conventional bleaching process, a washing step to remove the ferrous ions from the bleached kaolin suspension was indispensable, which made the process complicated and restricted the capacity of the production. In addition, the whiteness of the bleached kaolin products was unstable. To solve the above problems, a new technique with the application of chelating agents in the bleaching process was developed to remove ferrous ions and get rid of the washing step. The bleaching process of kaolin was simplified. The whiteness of the bleached kaolin products was stabilized as well as increased to about 70%. The mechanism of the bleaching process and the action of the chelating agents were discussed.

A feasibility study on cleaning Pb-contaminated soil with chelating agents

In this paper, the complexing abilities of EDTA, TTHA and Cit. with lead in the Pb(2.59 mg/g) contaminated soil were compared in the laboratory. Possibilities for lead and the threeagents to develop stable complexes increased proportionally to the growth of lead complexible formwhen the PH values ranged between 4 and 6. Under acid conditions, logB_(Pb-TTHA)) valued as 28.1 wasmuch higher than logB_(Pb-EDTA), as 18.0 depending on producing Pb_2-TTHA (logK_(Pb_2-TTHA= 11 0) andPb-HTTHA (logK(Pb-HTTTHA)=8.2)). Conclusively, the complexing ability of TTHA with Pb still ex-aseded that of EDTA by about 10% even when the amount of TTHA added was only equal to onefourth of that of EDTA. Due to the lower cost and less harzn to crops, Cit. can still be taken as abetter chelating agent in acid soil although its coordinative capability with Pb was weaker thanEDTA and TTHA.

STUDIES ON THE COMPETITION FOR CADMIUM ION BETWEEN CHELATING AGENTS AND BOVINE SERUM ALBUMIN

Eleven chelating agents were studied for their capabilities to mobilize the cadmium bound tp bovine serum albumin(BSA).The parameter F,which is defined as the ratio between the percentages of cadmium bound to BSA in the presence and absence of chelating agents,can be used as the criterion to evaluate the mobilizing capability of chelating agent.The F values determined experimentally lead to a mobilizing capability order:DTPA>EDTA>EGTA>NTA>TR1EN>PEN>CYS>HIS>SAThe polyaminopolycarboxylate type chelators mobilize cadmium effectively.A linear relationship was found between 1gF and lg k'CdL (conditional stability constant of the cadmium chelate).

Catechol-Bisphosphonate Conjugates: New Potential Chelating Agents for Metal Intoxication Therapy

In a quest for better chelating therapy drugs for the treatment of intoxication by Fe, Al, oractinides, two new series of mixed catechol-bisphosphonate through amide linkage were synthesized.Benzyl group was used as protecting group to avoid the breakage of amide by acid hydrolysis orimcomplete reaction in silylation-dealkylation using bromotrimethylsilane.

A NEW BIFUNCTIONAL CHELATING AGENT α,ε-N,N'-BIS(L-CYSTEINYL)-L-LYSINE FOR RADIOLABELLING OF MONOCLONAL ANTIBODIES WITH TECHNETIUM-99M

α,ε-N,N'-bis(L-cysteinyl)-L-lysine was synthesized and char- acterized for the first time.It was then employed as a bifunctional chelating agent to chelate technetium-99m and subsequently conjugated to fragment F(ab')_2 of anti-gastric tumor monoclonal antibody 3G9.The radiolabelled antibody was satisfactorily stable and immunoreactive.

Study on Treatment of Heavy Metals in Fly Ash by a Chelating Agent

The fly ash from two municipal solid waste incineration plants in Shanghai was treated by the self-developed organic composite chelating agent. The results indicated that the stabilization effect of Pb in the fly ash by the composite chelating agent was the best,and the proportions of its easily leaching form in the two kinds of fly ash decreased from 29. 60% and 27. 49% to 3. 05% and 0. 29% respectively. The leaching toxicity of stabilized fly ash was lower than the limits of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste（ GB 16889- 2008）,so it can be landfilled separately in the landfill site of municipal solid waste.

Application of a macromolecular chelating agent in chemical mechanical polishing of copper film under the condition of low pressure and low abrasive concentration

The mechanism of the FA/O chelating agent in the process of chemical mechanical polishing （CMP） is introduced. CMP is carried on a φ300 mm copper film. The higher polishing rate and lower surface roughness are acquired due to the action of an FA/O chelating agent with an extremely strong chelating ability under the condition of low pressure and low abrasive concentration during the CMP process. According to the results of several kinds of additive interaction curves when the pressure is 13.78 kPa, flow rate is 150 mL/min, and the rotating speed is 55/60 rpm, it can be demonstrated that the FA/O chelating agent plays important role during the CMP process.

Synergetic effect of chelating agent and nonionic surfactant for benzotriazole removal on post Cu-CMP cleaning

The cleaning of copper interconnects after chemical mechanical planarization （CMP） process is a crit- ical step in integrated circuits （ICs） fabrication. Benzotriazole （BTA）, which is used as corrosion inhibitor in the copper CMP slurry, is the primary source for the formation of organic contaminants. The presence of BTA can degrade the electrical properties and reliability of ICs which needs to be removed by using an effective cleaning solution. In this paper, an alkaline cleaning solution was proposed. The alkaline cleaning solution studied in this work consists of a chelating agent and a nonionic surfactant. The removal of BTA was characterized by contact angle measurements and potentiodynamic polarization studies. The cleaning properties of the proposed cleaning solution on a 300 mm copper patterned wafer were also quantified, total defect counts after cleaning was studied, scanning electron microscopy （SEM） review was used to identify types of BTA to confirm the ability of cleaning solution for BTA removal. All the results reveal that the chelating agent can effectively remove the BTA residual, nonionic surfactant can further improve the performance.

Annealing effects on the structural and optical properties of ZnO nanoparticles with PVA and CA as chelating agents

The effects of annealing temperatures and chelating agents on the structural and optical properties of ZnO nanoparticles were investigated.The average particle size of ZnO nanoparticles increased with increase of annealing temperatures.The decrease of the full width at half maximum(FWHM)with increasing annealing temperatures inferred increase of particle/grain growth.The grain sizes were also observed to be increased with increase of annealing temperatures.From the absorption spectra of the samples,the absorption was red-shifted and the energy band gap was blue-shifted with increase of annealing temperatures.A sharp UV emission peak was observed and the intensity of this peak increased with annealing temperatures corresponding to the high crystallinity in the samples.At high annealing temperature of 700℃,ZnO exhibited a less intense deep level emission.This negligible deep level emission was attributed to the oxygen vacancies created at higher annealing temperatures.

Environmentally relevant concentrations of aminopolycarboxylate chelating agents mobilize Cd from humic acid

Although Cd is a pollutant of public health relevance,many dietary sources from which it can be absorbed into human tissues remain unknown.While it is well established that the biogeochemical cycle of Cd involves its complexation with environment-derived ligands（e.g.,humic acids,HAs） and anthropogenic ones（e.g.,chelating agents,CAs）,the interaction of Cd with both of these ligands is less well understood.To gain insight,a HA–Cd complex was injected on a size-exclusion chromatography（SEC） column coupled on-line with a flame atomic absorption spectrometer（FAAS） using 10 mmol/L Tris buffer（pH 8.0） as the mobile phase.This approach allowed us to observe the intact HA–Cd complex and the retention behavior of Cd as a function of 2–20 μmol/L concentrations of ethylenediaminetetraacetic acid（EDTA）,diethylenetriaminepentaacetic acid（DTPA） or methylglycinediacetic acid（MGDA） that were added to the mobile phase.An increase of the retention time of Cd was indicative of a partial or complete abstraction of Cd from HA.Our results revealed that all CAs abstracted Cd from the HA–Cd complex at concentrations of 5 μmol/L,while MGDA and DTPA were effective at 2 μmol/L.The bioavailability of some of the on-column formed CA–Cd complexes explains the previously reported increased accumulation of Cd in periphyton in the ecosystem downstream of wastewater treatment plants.In addition,our results imply that the use of effluents which contain CAs and Cd for the irrigation of food crops can introduce Cd into the food supply and compromise food safety.

Next generation barrier CMP slurry with novel weakly alkaline chelating agent

To strengthen the device performance with the pattern wafer by enhancing the Cu polishing rate and improve the surface roughness with the Cu lines, a new weakly alkaline chelating agent with a barrier slurry is developed to meet the process demand of the advanced barrier chemical mechanical planarization（CMP）. This new chelating agent has a stronger chelating ability and a lower p H value than the previous generation-FA/O I chelating agent researched before. Without an unstable oxidant agent added in the polishing slurry, it is difficult to enhance the copper polishing rate during the barrier CMP. The stronger chelating ability of the new chelating agent could increase the copper polishing rate along with controlling the Cu/Ta/TEOS removal rate selectivity to meet the requirements of the IC fabrication process. Thus it has solved the problem of excessive roughness due to the lower polishing rate, avoiding reducing the device performance with the pattern wafer. The new chelating agent with its lower p H value could make it possible to protect the low-k dielectric under the barrier layer from structurally breaking. The CMP experiment was performed on the 12 inch MIT 854 pattern wafers with the barrier slurry containing the new weakly alkaline chelating agent. By the DOE optimization, the results indicate that as the new chelating agent concentration in the slurry was up to 2.5 m L/L, the copper polishing rate is about 31.082 nm/min.Meanwhile, the wafer surface has a rather low roughness value of 0.693 nm（10×10 μm）, the correction ability with the above slurry is adapted to the next generation barrier CMP and the k value of the low-k dielectric seems to have no k-shift. All the results presented show that the new weakly alkaline chelating agent with its superior performance can be used for the advanced barrier CMP.

Pore-scale study of the effects of DTPA chelating agent flooding on oil recovery utilizing a clay-coated micromodel

The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been proposed for chelating agent flooding;however,little attention has been paid to fluid-fluid interaction thus far.The assessment of these mechanisms has primarily relied on macroscopic techniques such as core flooding.This paper aims to investigate the injection of DTPA brine and its dominant mechanisms at the pore scale using a clay-coated micromodel.The micromodel tests were performed under oil-wet and water-wet states.For a more precise examination of fluid/fluid interactions,the dynamic interfacial tension(IFT)and Zeta potential were measured.It was observed that the injection of DTPA brine in water-wet state changed the saturation distribution and increased oil recovery.Based on visual inspections,this change in saturation distribution could potentially be linked to the formation of micro-dispersions and viscoelastic interfacial phenomena.Micro-dispersions facilitate flow to unswept areas,and viscoelastic interface formation reshapes the interface between oil and brine,causing disconnected oil droplets to coalesce and thus increase recovery.Under the oil-wet state,the micro-dispersion formation and wettability alteration can be the dominant mechanisms,and the amount of recovered oil was higher than that observed in the water-wet state.Furthermore,Zeta potential measurements at the interface between brine and oil showed a more negative value for DTPA brine,which is effective in wettability alteration and micro-dispersions stability.The results indicate that IFT reduction was not significant enough to be considered the dominant mechanism,although it assists in DTPA brine penetration into the crude oil and subsequent micro-dispersion formation.

螯合活化剂对孔雀石的活化及其对氧化铜矿石浮选应用

对采自云南红河、兰坪、东川及湖北大冶铜绿山的四个孔雀石样品,进行了分别使用D2(2、5——二硫酚——1、3、4——硫代二唑)及硫化钠作活化剂,黄药作捕收剂的单矿物浮选试验。研究了不同矿区孔雀石浮选基本行为间的差别、D2药剂作用规律及适用范围。对于以D2作活化剂,用黄药从氧化矿石中直接浮选未经预先硫化的氧化铜矿物新工艺的实践经验及结果也作了报道。

Evaluation of formation damages during filter cake deposition and removal process:The effect of primary damage on secondary damage

The properties of oil and gas formation could be significantly damaged during drilling and completion operations as a result of mud invasion,fluid incompatibility and interaction with rock minerals.This paper presents a systematic method for evaluating formation damage during filter cake deposition(primary damage)and removal process(secondary damage).The role of primary damage in the evolution of secondary damage was also investigated.The interaction of the filter cake solvent(chelating agent solution)with the rock samples was implemented through core flooding experiment.Nuclear Magnetic Resonance(NMR)was used to evaluate the properties of the rock sample,pre and post filter cake deposition and removal processes.The results show that secondary damaged is a strong function of the location and the intensity of the primary damage.The rock type and its pore structure also play important roles in both primary and secondary damage.The extent of secondary damage depends on the amount of barium sulphate deposited during primary damage.The chelating agent used to dissolve the barites in sandstones,deposited the barite in the small pores while it enlarges the bigger pores.In contrast,the chelating agent in the carbonate samples had multiple barite deposition points.

Influence of Combined Therapeutic Potential of Meso 2, 3-dimercaptosuccinic Acid and Calcium Disodium Edetate on Lead-induced Testicular Alterations in Rats

The therapeutic efficacy of a combinaion of meso 2,3-dimeroaptosuccinic acid (DMSA) and calcium disodium EDTA in protecting testicular disorders in chronic lead intoxication was investigated. The results indicate that two five-days courses of the combined therapy produced a more effective recovery in the lead induced biochemical and histopahological disorders compared to conventional single 5 days therapy. No adverse effect of the chelators, when administered individually or in combination, was noticed in the testes of control (without lead exposure) animals.

Study on a New Method of Extraction of Metal Ions from SolidMatrices by Supercritical Fluid

8-Hydroxyquinoline, methanol and Triton-100 were first used together in the extraction of metal ions by supercritical CO2. In the new system, the effects of pressure, temperature and the volume of CO2 on the efficiency of supercritical fluid extraction (SFE) were systematically investigated. The recovery under the optimum condition was only 11.38%, but if suitable concentration of methanol (v/v=5%) was added to the supercritical CO2, the recovery was increased significantly (83.60%, RSD=4.37%, n=5). In order to further enhance the recovery Triton X-100 was added to the samples, and the results were satisfactory (96.62%, RSD=2.85%, n=5).