Copper Impregnation Research Articles

Effect of pv factor on carbo-graphite and copper impregnated carbo-graphite material under dry conditions

This study investigates the tribological behaviour of copper-impregnated carbo-graphite (ICG) compared to plain carbo-graphite (CG) under various parameter-product (PV) values and temperatures. Impregnation significantly enhanced ICG's hardness (70%) and reduced porosity (98.6%) compared to CG. The CoF for CG was lower than that for ICG attributed to the formation of a lubricating graphite-rich tribo-film that facilitated easy shearing at the contact interface. The wear mechanisms for CG at elevated temperatures were identified as adhesion, oxidation and delamination, likely exacerbated by the material's softening. In contrast, ICG exhibited superior wear resistance, attributed to its higher hardness and the formation of a protective tribo-layer containing copper and graphite. This tribo-layer offered a low-shear interface at lower PV values, reducing friction. However, at higher PV values, ICG wear increased due to abrasion and adhesion. Overall, copper impregnation offers a promising strategy to improve the wear resistance of carbo-graphite, particularly at elevated temperatures.

Evaluation of the Mineral Manganese OXMN009 and OXMN009P in the Chemical Looping Combustion (CLC) Process Using Thermogravimetry

Indirect combustion with the chemical looping combustion (CLC) of solid oxygen carriers is one of the most promising technologies for capturing carbon dioxide (CO2) in energy production from fossil fuels since the separation of the generated CO2 is inherent to the process itself. Therefore, the cost associated with capturing this gas will be significantly reduced. This technology transfers oxygen from air to fuel through a metal oxide that acts as an oxygen carrier, avoiding direct contact between air and fuel. This oxygen carrier circulates in a fluidized bed reactor called a reduction reactor and an oxidation reactor. (1) This research work has focused on evaluating the behavior of oxygen carriers based on the original and improved manganese mineral (copper-impregnated mineral) named for this study, OXMN009 and OXMN009P, respectively. (2) Equilibrium experiments were carried out on a thermogravimetric balance (TGA) to evaluate the kinetic behavior of these oxygen transporters OXMN009 and OXMN009P, using the gases methane (CH4), carbon monoxide (CO), and hydrogen (H2). (3) The enhanced solid oxygen carrier OXMN009P exhibited good performance for the CLC process with gaseous fuels in terms of reactivity and combustion efficiency, having high reactivity and oxygen transfer properties due to copper impregnation. (4) The results show that OXMN009P has comparable reactivity to other manganese-based materials reported in the literature. It may be an effective option for carbon dioxide capture, as it uses metal oxides as the oxygen transporters (TO). (5) These oxygen transporters, OXMN009 and OXMN009P, are used in a cyclic process that prevents the formation of nitrogen oxides by keeping the air and fuel separate. (6) Thermogravimetric balance (TGA) experiments were conducted to evaluate the kinetic behavior of these copper-modified oxygen transporters. (7) It was found that OXMN009P improved the reactivity and oxygen transfer properties due to copper impregnation. The kinetic parameters obtained in the TGA indicate that the reaction is non-thermal and requires less energy to initiate. (8) The results show that OXMN009P has reactivity comparable to other manganese-based materials reported in the literature and can be an effective option for carbon dioxide capture.

Ammonia gas adsorption study using copper impregnated on mesoporous activated carbon from seaweed waste for indoor air purification

Ammonia (NH3), as a toxic gas, has negative impacts on human health even at low concentration, especially in narrowed spaces. In this study, activated carbon was synthesized from seaweed waste and copper was loaded on its surface (Cu/AC filter) to prepare a cost-effective NH3 adsorbent. Pyrolysis (carbonization) temperature can significantly affect the texture properties of activated carbon, and the best activated carbon sample with BET of 1114 m2/g was obtained through pyrolysis at 500 °C followed by KOH-activation at 750 °C. Different from other lignocellulosic biomass-based activated carbons (mainly microporous structure), the prepared algae-based activated carbons mainly have a mesoporous structure (pore size: 7.0–9.0 nm). Copper-impregnation significantly changed the surface chemistry of activated carbon, thereby greatly increasing the NH3 adsorption capacity (max: 128.6 mg/g). The adsorption performance was primarily determined by chemical adsorption (caused by copper impregnation and related inherent functional groups, including O–H, C–H, O–Si–O and SiO–H), followed by physical adsorption (caused by BET). Isotherm studies indicated that NH3 adsorption on Cu/AC filter followed the Langmuir model, whereas the adsorption kinetics followed the pseudo-second-order model. Furthermore, the adsorption mechanism was controlled by intraparticle diffusion model with initial adsorption behavior. This can be attributed to the mesoporous structures of activated carbon, consequently dramatically improving the diffusion efficiency. In addition, the Cu/AC filter showed good regeneration performance, as it can still remain above 90 % after 5 cycles. Finally, this study demonstrated that the seaweed waste is a good precursor for activation carbon and has great potential as excellent NH3 adsorbent for indoor air purification.

Keratin/Copper Complex Electrospun Nanofibers for Antibacterial Treatments: Property Investigation and In Vitro Response.

The frontiers of antibacterial materials in the biomedical field are constantly evolving since infectious diseases are a continuous threat to human health. In this work, waste-wool-derived keratin electrospun nanofibers were blended with copper by an optimized impregnation procedure to fabricate antibacterial membranes with intrinsic biological activity, excellent degradability and good cytocompatibility. The keratin/copper complex electrospun nanofibers were multi-analytically characterized and the main differences in their physical-chemical features were related to the crosslinking effect caused by Cu2+. Indeed, copper ions modified the thermal profiles, improving the thermal stability (evaluated by differential scanning calorimetry and thermogravimetry), and changed the infrared vibrational features (determined by infrared spectroscopy) and the chemical composition (studied by an X-ray energy-dispersive spectroscopy probe and optical emission spectrometry). The copper impregnation process also affected the morphology, leading to partial nanofiber swelling, as evidenced by scanning electron microscopy analyses. Then, the membranes were successfully tested as antibacterial materials against gram-negative bacteria, Escherichia coli. Regarding cytocompatibility, in vitro assays performed with L929 cells showed good levels of cell adhesion and proliferation (XTT assay), and no significant cytotoxic effect, in comparison to bare keratin nanofibers. Given these results, the material described in this work can be suitable for use as antibiotic-free fibers for skin wound dressing or membranes for guided tissue regeneration.

Hydrogenation of Carbon Dioxide to Dimethyl Ether on CuO–ZnO/ZSM-5 Catalysts: Comparison of Powder and Electrospun Structures

The promising direct dimethyl ether (DME) production through CO2 hydrogenation was systematically analyzed in this research by synthesizing, characterizing, and testing several catalytic structures. In doing so, various combinations of precipitation and impregnation of copper- and zinc-oxides (CuO–ZnO) over a ZSM-5 zeolite structure were applied to synthesize the hybrid catalysts capable of hydrogenating carbon dioxide to methanol and dehydrating it to DME. The resulting catalytic structures, including the co-precipitated, sequentially precipitated, and sequentially impregnated CuO–ZnO/ZSM-5 catalysts, were prepared in the form of particle and electrospun fibers with distinguished chemical and structural features. They were then characterized using XRD, BET, XPS, ICP, TGA, SEM, and FIB-SEM/EDS analyses. Their catalytic performances were also tested and analyzed in light of their observed characteristics. It was observed that it is crucial to establish relatively small-size and well-distributed zeolite crystals across a hybrid catalytic structure to secure a distinguished DME selectivity and yield. This approach, along with other observed behaviors and the involved phenomena like catalyst particles and fibers, clusters of catalyst particles, or the whole catalytic bed, were analyzed and explained. In particular, the desired characteristics of a CuO–ZnO/ZSM-5 hybrid catalyst, synthesized in a single-pot processing of the precursors of all involved catalytically active elements, were found to be promising in guiding the future efforts in tailoring an efficient catalyst for this system.

The catalytic activity of copper/nickel supported on mesoporous aluminum catalyst towards cyclohexene epoxidation in continuous reactor

The intent of the study is to attain a high selectivity rate and stable interaction between metals in any heterogeneous catalyst. Cyclohexene is extremely valuable in industrial domains such as the synthesis of perfumes and nylons, and the mesoporous alumina was upstretched with a various ratio of bimetal copper (10%) and nickel (5%, 10%, 15%, and 20%) under wet impregnation procedures by the mesoporous aluminum catalyst. This impregnation of a metal and catalyst was used to assess the highest conversion and selectivity of cyclohexene to cyclohexanol. This catalytic nature was validated by analyzing the crystal structure and size using the X-ray diffraction technique. The functional group is identified using FT-IR (Fourier Transform Infrared Spectroscopy), while the surface area is assessed using BET (Brunauer-Emmet-Teller). HR-TEM (transmission electron microscopy) is used to validate the morphology of catalysts and their surface layers; HR-SEM (Scanning Electron Microscopy) is used to highlight and assess microparticles; and NH3TPD (Temperature-Programmed Desorption) is used to measure the overall acidity of the catalyst. The catalytic performance was proved by the yield achieved by varying parameters such as temperature, pressure, WHSV−1, reaction time, and solvents, which yielded over 98.5% in both cyclohexene conversion and selectivity. In the conversion of the product, H2O2 performs as an oxidant, and acetonitrile serves as a solvent at constant mild conditions of 90 °C and 20 bar pressure. Furthermore, even after seven successive runs with the Al2O3/Cu (10%)-Ni (15%) mixture, remarkable reusability was attained despite a minor decline in cyclohexanol selectivity. The effective impregnation of copper and nickel into supported mesoporous Al2O3 produced a long-lasting, stable hybrid nanostructure with excellent stability and no metal leaching. The current synthesis protocol's advantages and qualities include its efficiency, cost-effectiveness, ecological sustainability, and comfort of synthesis with readily available components.

ZrO2/SO4/Cu nanoparticles supported on reduced graphene oxide for selective oxidation of propylene glycol in continuous reactor

In this study, a first effort at converting propylene glycol to hydroxyacetone using a continuous reactor was made. The method for creating copper-infused sulfated zirconium oxide heterogeneous bimetallic nanoparticles supported on reduced graphene oxide as the catalyst is described in the paper. The synthesized rGO/ZrO2(10%)/SO42−(4%)/Cu (5–20%) nano-catalyst, possessing various active Brønsted and Lewis acid sites were employed for the selective oxidation of the propylene glycol reaction. Utilizing affordable, easily accessible ingredients and a simple, straightforward synthesis process, the catalyst was created. XRD, FT-IR, BET, HR-SEM, HR-TEM, TGA, and temperature-programmed desorption (TPD) characterization techniques were employed to determine the stability, morphology, textural characteristics, and chemical properties of catalysts. The experiment involved the selective oxidation of propylene glycol (PG) in a continuous reactor at 90 °C, a WHSV of 1.0 h−1, a pressure of 10 bar, and an O2 flow rate of 1.0 mol h−1. Tert-butyl hydroperoxide (TBHP) was used as the solvent. Hydroxyacetone (HA) was the primary oxidation product, whereas methylglyoxal (MGO) was obtained as the secondary product. The study's findings show that rGO-supported sulfated zirconium oxide with 15% copper displayed outstanding catalytic activity and stability, outperforming the other studied catalysts in conversion (97.6%) and selectivity (99.4%). Further, excellent reusability with a negligible drop in HA selectivity was achieved even after seven consecutive runs in the presence of the rGO/ZrO2/SO4/Cu(15%). A successful copper impregnation into sulfated zirconia supported by rGO produced a long-lasting, stable hybrid nanostructure that had good stability and no metal leaching feature. The advantages and features of the current synthesis protocol are its efficiency, cost-effectiveness, eco-friendliness, and ease of preparation with readily available materials.

Investigation of Nigerian Coconut Shell and Banana Peels for the Removal of Carbon Monoxide (CO) in Indoor Environment

In this study, copper chloride modified activated carbon was synthesised by thermal monolayer dispersion (deposition) process. Characterization of the adsorbents were carried out using Fourier Transform Infrared Spectroscopy (FTIR), proximate analysis and ultimate analysis. Furthermore, Response Surface Methodology (RSM) and Artificial Neural Network (ANN) were combined to determine the optimum conditions at which the synthesised adsorbent can remove carbon monoxide from the ambient environment. It cost implication was also determined. This was with a view to examine the Carbon Monoxide removal potential of the synthesised adsorbent. The characterization results showed that the prepared activated carbon are suitable precursor for the impregnation of copper (I) chloride. The RSM showed the optimum condition to be 20g CuCl/CSAC for 10mins with predicted CO adsorption of 77.01% with R2 value of 0.9843 and 15g of CuCl/BPAC for 10mins with predicted CO adsorption of 69.71% with R2 value of 0.9759. The ANN results were 25g CuCl/CSAC for 10mins with predicted CO adsorption of 77.15% with R2 value of 1 and 20g of CuCl/BPAC for 10mins with predicted CO adsorption of 69.17% with R2 value of 1. The ANN model indicates a better accuracy over RSM.

Effect of atomic layer deposited zinc promoter on the activity of copper-on-zirconia catalysts in the hydrogenation of carbon dioxide to methanol

The development of active catalysts for carbon dioxide (CO2) hydrogenation to methanol is intimately related to the creation of effective metal-oxide interfaces. In this work, we investigated how the order of addition of copper and zinc on zirconia influences the catalytic properties, the catalytic activity and selectivity toward methanol. Regarding the carbon dioxide conversion and methanol production, the catalysts on which the promoter (zinc) was atomically deposited after copper impregnation (i.e., ZnO/Cu/ZrO2 and ZnO/Cu/ZnO/ZrO2) were superior catalysts compared to the reverse copper-after-zinc catalyst (Cu/ZnO/ZrO2). Temperature-programmed experiments and in situ diffuse reflectance infrared Fourier transform-spectroscopy (DRIFTS) experiments allowed us to elucidate the benefits of the zinc-after-copper pair to store CO2 as carbonate species and further convert them into formate species, key intermediates in the formation of methanol. This research provides insights into the potential of atomic layer deposition in the development of tailored heterogeneous catalysts for efficient CO2 valorization to methanol.

Virus removal from drinking water using modified activated carbon fibers.

Activated carbon (AC) exhibits superior sorption properties compared to other porous materials, due to well-developed porous structures and high surface areas. Therefore, it is widely applied in its various forms in water purification to remove a diverse range of contaminating species. The presence of viruses in fresh water bodies poses a serious issue for human health. However, AC has not yet been commonly applied to waterborne virus removal. In this study, we present oxidation and copper impregnation treatment procedures of activated carbon fibers (ACFs) that resulted in porous structure and surface chemistry modifications. The effect of these modifications on virus removal was investigated by experimental flow studies and revealed up to 2.8 log10 reduction value (LRV) and 3.6 LRV of MS2 bacterio-phages for non-modified and oxidized ACFs, respectively, emphasizing the advantages of ACF surface functionalization. Copper modified fibers demonstrated a high sensitivity to media composition, resulting in a release of metal and therefore limited virucidal capacity.

Features of the Formation of an Interface Zone Structure during Thermal Diffusion Metallization of Diamond by Transition Metals

The features of the morphology and chemical and structural-phase compositions of the diamond–metal interface zone formed in the process of thermal diffusion metallization of diamond by chromium, titanium, iron, nickel, and cobalt powders under the same temperature–time mode of the vacuum furnace operation that corresponds to the mode of sintering of diamond-containing WC–Co matrix with copper impregnation are studied. In the process of thermal diffusion metallization by chromium and titanium, a metalized coating is formed on the diamond surface, consisting of a phase mixture of carbides, metals, and graphite of variable composition. The small content of graphite formations and their discontinuous character of location in the diamond–metal interface zone ensure a strong adhesion of the metalized coating to the diamond through the carbides of the corresponding metals. During thermal diffusion metallization by iron, the intermediate layer strongly adhering to the diamond is also formed in the diamond–metal interface zone. The intermediate layer has a complex structural-phase composition comprising a mixture of iron phases, a solid solution of carbon in iron, and graphite of variable composition. An assumption is made that the intermediate layer could be formed on the surface of diamond grains by solidification of the liquid phase with eutectic composition, resulting from the eutectic melting of the diamond–iron contact pairs. However, the confirmation of this assumption requires performing special experiments using highly sensitive methods of research. Under the heating conditions specified in the experiment, the nickel–cobalt and cobalt–diamond interaction causes intense catalytic graphitization of diamond followed by the formation of numerous traces of erosion on its surface. The observed weak adhesive interaction of these metals with diamond is likely to be determined by the high melting temperatures of the Ni–C and Co–C eutectics, which does not allow the metals to react with diamond actively under the specified experimental conditions.

Alternative wood preservation method: double treatment and its effectiveness against wood decay fungi

In this study, two single wood treatments—copper impregnation (I) with thermo-hydro treatment (T) and vice versa—were combined to determine the effectiveness against wood decay fungi. Pine (Pinus sylvestris L.) sapwood and birch (Betula spp.) boards were treated accordingly, then cut into small-size specimens and exposed to brown rot (Coniophora puteana) and white rot (Trametes versicolor) fungi to determine mass loss (ML). The specimens were collected from the board ends and middle part to detect copper distribution and, consequently, decay resistance. Wood leaching according to EN 84 was performed to evaluate the double treatment efficiency in outdoor conditions (use class 3, EN 335). The durability of the board ends and middle part differed in single-impregnated wood. The higher amount of copper at the board ends tended to cause lower ML. Double-treated I/T boards showed a similar tendency. In double-treated T/I wood, a higher copper amount at the board ends provided a higher ML in this part. Obviously, the interaction between thermal and chemical treatment has affected the wood structure, copper distribution and fixation. In leached pine and birch wood, the double treatments T/I and I/T were more efficient against brown rot than single thermo-hydro treatment and impregnation procedures, ensuring the durability class (DC) 2 (CEN/TS 15083–1). Regarding white rot, there was no pronounced difference between both double treatments and single treatments as they ensured DC1.

Oxidative dehydrogenation of ethanol over Cu/Mg-Al catalyst derived from hydrotalcite: effect of ethanol concentration and reduction conditions

The copper-modified Mg-Al catalyst (Cu/Mg-Al) was synthesized using the incipient wetness impregnation of copper onto the Mg-Al hydrotalcite derived from co-precipitation method. The effects of copper on the characteristics of catalyst were obtained using several characterization techniques. We found that only copper (I) oxide (CuO) species were obtained on the surface after calcination in air by X-ray Diffraction (XRD). However, the basicity of the base decreases slightly, while the density of the base increases due to the decrease in Brunauer-Emmett-Teller (BET) surface area. We carried out the catalytic activity of the Cu/Mg-Al catalyst in the continuous flow reactor through oxidative dehydrogenation of ethanol. We obtained that the copper enhances the catalytic activity in this reaction, and the ethanol conversion increases with increase in temperature, while the acetaldehyde selectivity decreases because of the decomposition of acetaldehyde to carbon dioxide. The highest acetaldehyde yield of 41.8% was at 350 °C. Moreover, we studied the effects of the ethanol concentration by varying the ethanol feed concentrations (99.9%, 75%, and 50%). The ethanol conversion decreases with a decrease in the ethanol concentration due to the high adsorption of water molecules on the catalyst surface. Thus, the negative effect decreases at higher reaction temperature (350–400 °C). Furthermore, we investigated the effect of the reduction condition of catalyst by varying the reduction temperature (300 and 400 °C). The reduction process affects the catalytic activity. The Cu/Mg-Al was comparatively stable for 10 h upon time-on-stream test. It is used as a promising catalyst in oxidative dehydrogenation of ethanol without any reduction step.

Features of the interfacial zone structure formation during thermal diffusion metallization of diamond by transition metals

The paper studies morphology, chemical, structural and phase composition of the diamond-metal interphase zone, formed in the process of thermal diffusion metallization of diamond with chromium, titanium, iron, nickel and cobalt powders with the same temperature-time mode that corresponds to the sintering of diamond-containing WC-Co-matrices with copper impregnation. In the process of thermal diffusion metallization of chromium and titanium, a metalized coating is formed on the surface of the diamond, consisting of a mixture of carbides, metals and graphite of variable composition phases. The insignificant content of graphite formations and their intermittent nature of the diamond-metal interfacial zone ensure a strong adhesion of the metalized coating to the diamond through the carbides of the corresponding metals. When thermal diffusion metallization of diamond with iron occurs at the diamond-metal interfacial zone, the formation of an intermediate layer strongly adhered to the diamond also takes place. The intermediate layer has a complex structural phase composition comprising a mixture of iron phases, a solid solution of carbon in iron and graphite of variable composition. An intermediate layer on the surface of diamond could be formed by solidification of the liquid phase with the eutectic composition resulting from the eutectic melting of the diamond-iron contact pairs. However, this assumption requires additional research to confirm it, and special experiments using highly sensitive research methods. Under the heating conditions specified in the experiment samples of nickel-diamond and cobaltdiamond cause intense catalytic graphitization of diamond with the formation of numerous traces of erosion on its surface. The observed weak adhesive interaction of these metals with diamond is probably due to the high melting temperatures of the Ni-C and Co-C eutectics, which does not allow the metals to react with diamond under given experimental conditions.

Valorization of Eggshell Waste into Supported Copper Catalysts for Partial Oxidation of Methane

Agricultural wastes are equipped with unique physicochemical traits that may be harnessed to obtain valuable end products. Therefore, the present research focused on using waste eggshells as precursors for the synthesis of catalysts for partial oxidation of methane. Catalysts were synthesized via impregnation of copper on calcined eggshell surfaces. The catalysts were tested for selective oxidation of methane at 650° C and atmospheric pressure. Eggshells loaded with 2% copper activated partial oxidation pathway to enhance yield for syngas, while 5% and 10% loading led to C2–C6 hydrocarbons as a result of oxidative coupling of methane. Oxygen concentration in the feed along with feed flow rate and temperature influenced both fractional conversion and product selectivities. Limited-oxygen supply and adequate flow rate of 0.8 L min−1 at 650° C provided better conversion with 10% Cu-loaded catalyst. While the fresh catalyst exhibited a uniform distribution of copper and a smooth catalyst surface, little surface deformation was observed in the spent catalyst. Prolonged catalytic activity was also investigated via catalyst reactivation. Our results suggest that waste eggshells may be used as catalyst supports for metals to be used in oxidation reactions.

Adsorptive removal of trivalent and pentavalent arsenic from aqueous solutions using iron and copper impregnated melanin extracted from the marine bacterium Pseudomonas stutzeri

The metalloid arsenic is one of the most conspicuous groundwater contaminants in the Indian subcontinent and its removal from aqueous medium is the main focus of this study. The study aims at functionalising melanin using iron and copper for the efficient removal of arsenic and rendering water fit for consumption. Melanin obtained from the marine bacteria Pseudomonas stutzeri was functionalised by iron impregnation (Fe-melanin) and copper impregnation (Cu-melanin). Morphological studies using FESEM portrayed the impregnated iron and copper granules on the surface of melanin, while XRD analysis confirmed the presence of Fe2O3 and CuO on melanin. Adsorption studies on As (V) and As (III) were conducted using Fe-melanin and Cu-melanin for different operating variables like pH, temperature and contact time. More than 99% per cent of As (III) and As (V) from water was removed at a pH range between 4 and 6 within 50 min in the case of Fe-melanin and 80 min for Cu-melanin. Adsorption equilibrium studies showed better fit with Langmuir adsorption isotherm and had good agreement with Redlich-Peterson’s three-parameter model. The maximum adsorption capacities of Fe-melanin and Cu-melanin obtained from Langmuir adsorption model are 50.12 and 20.39 mg/g, respectively, for As (V) and similarly 39.98 and 19.52 mg/g, respectively, for As (III). Arsenic-binding to the functionalised melanin was confirmed using FT-IR and the XPS analysis. Reuse of the adsorbent was effectively done by desorbing the iron and copper together with the bound As (III) and As (V) and further re-impregnation of iron and copper in melanin. Re-functionalised melanin showed 99% adsorption efficiency up to four cycles of adsorption/desorption.

Correlation of the Diamond/Matrix Interphase Zone Structure with Tool Efficiency Obtained by Technology Combining Metallization of Diamonds with Matrix Sintering

The paper studies the structure and phase characteristics of the interphase zone diamond/matrix in dressers made by thermal diffusion metallization of a diamond combined with matrix sintering based on WC–Co and Cu impregnation. The compact arrangement of chromium powder particles around diamond grains and the shielding effect of copper foil create favorable conditions for thermal diffusion metallization of diamond at matrix sintering. A metallized coating chemically bonded to diamond and consisting of chromium carbide and solid solution of cobalt in chromium phases provides a strong diamond retention in the carbide matrix. It is shown that it is formed on the surface of the diamond under the conditions specified in the experiment and the temperature–time sintering mode. The specific productivity of experimental dresser made by hybrid technology at straightening the green silicon carbide grinding wheel equaled 51.50 cm3/mg, exceeding that of the control dresser made without metallization of diamonds by sintering with copper impregnation by 44.66%.

Structure of a Diamond–Matrix Interface and Durability of a Diamond Tool Fabricated by the Metallization of Diamond with Chromium during Sintering of the WC–Co Briquette with Copper Impregnation

The structure, as well as the elemental and phase compositions of the diamond–matrix interface of a diamond tool for abrasive wheel dressing, manufactured using a new hybrid technology, are studied. This technology combines the thermodiffusion metallization of diamond with chromium and sintering of a matrix based on a WC–6%Co carbide powder mixture with copper impregnation in a single cycle of the vacuum furnace operation. During matrix sintering, the compact arrangement of chromium powder particles around the diamond grains and the screening effect of the copper foil form favorable conditions that ensure the thermodiffusion metallization of diamond. Scanning electron microscopy, electron probe microanalysis, X-ray phase analysis, and Raman spectroscopy show that a metallized coating chemically bound with diamond is formed on the diamond surface in temperature-temporal modes and sintering conditions. The coating consists of chromium carbide and a solid solution of cobalt in chromium, which provides durable diamond retention in the copper-impregnated carbide matrix. Herewith, the matrix structure and microhardness, excluding the regions adjoining the diamond–matrix interface, remain the same as a matrix of a carbide powder mixture sintered in the absence of chromium. Comparative tests of similar diamond dressers show the high efficiency of the hybrid technology of formation of diamond-containing composites for tool application. It is shown that the specific productivity of a dresser prototype fabricated using the hybrid technology was 51.50 cm3/mg when dressing a grinding wheel made of green silicon carbide, which is 44.66% larger than a similar indicator of the same type of check dresser formed using the traditional method.

In-situ copper impregnation by chemical activation with CuCl2 and its application to SO2 and H2S capture by activated carbons

H2S and SO2 are toxic compounds that are part of the main air pollutants. They can also induce corrosion and are responsible for acidic rain. Among the methods for their capture, adsorption on copper impregnated activated carbons is one of the most efficient. The latter are generally obtained in a two-step process, consisting of the preparation of the activated carbon and then its impregnation with copper. The aim of this work is to elaborate an efficient adsorbent of H2S and SO2 in one single step. This goal is reached by an in-situ impregnation of copper using an original technique based on chemical activation using CuCl2 as activating agent which, as far as we know, was not used before in this role, i.e. as the main activating agent. The carbonisation was carried out to 800 °C either in N2 or CO2. The obtained materials have a BET surface area of around 400 m2/g and a copper content by weight of about 20%. They were tested successfully against SO2 and H2S by breakthrough measurements. In fact, they showed better results than an activated carbon prepared by chemical activation with ZnCl2 (SBET 1600 m2/g). Thermogravimetric analysis before and after breakthrough tests allowed the proposition of possible mechanisms for the retention of H2S and SO2 on the prepared materials. This new one step preparation method using CuCl2 would permit a gain of time and energy for obtaining efficient activated carbons intended to capture SO2 and H2S.

Treatment of coke oven effluent using copper impregnated activated carbon: experiment and modelling

ABSTRACTIn the present study, plywood dust has been used as precursor to prepare activated carbon and copper as impregnating agent. Two methods have been employed to impregnate copper in activated carbon such as carbonisation with solid copper chloride salt and with copper chloride solution. The comparative studies between these two samples on removal of both cyanide and phenol have showed that impregnation with solid copper chloride gives better result. Response surface methodology (RSM) has been employed to optimise carbonisation vis-a-vis copper impregnation condition and the sample prepared at optimum condition is termed as copper impregnated activated carbon (CIAC). A comparative study between activated carbon without impregnation, commercial activated carbon and CIAC has showed that CIAC is more efficient in cyanide removal than other two adsorbents. Kinetic study has been done with the simulated solution of cyanide and phenol separately with CIAC by varying solution concentrations and weight of the adsorbent. RSM has also been used to optimise the removal of cyanide and phenol from the simulated coke oven effluent containing phenol and cyanide in varying proportions. Finally, real coke oven effluent has been treated with CIAC and the percentage removals of both cyanide and phenol have been examined.