A CO2 Capture Technology Using Multi-walled Carbon Nanotubes with Polyaspartamide Surfactant

Carbon Nanotubes (CNT) have emerged and gained great interest for research in many applications because of their unique specific characteristics such as having high porosity, high surface area and the existence of a wide spectrum of surface functional groups through chemical modification. Multiwalled carbon nanotubes (MWCNT) is a type of CNT that comprises of multiple layers of concentric cylinders. The overall study of this research work is to modify MWCNT to become a good adsorbent that can adsorb CO2 at its optimum capacity. In order to make MWCNT as an efficient adsorbent, surface treatment on pristine MWCNT is necessary to overcome the hydrophobicity issue by the introduction of carboxyl group. Upon the surface treatment, functionalization of MWCNT with 3-Aminopropyl triethoxysilane (APTS) was conducted to obtain the attachment of amine group that will assist MWCNT in adsorbing CO2. The surface treatment and functionalization process undergone by MWCNT changed the physical properties of MWCNT such as the surface area, pore volume, and pore size distribution. These properties can be determined using surface area and pore analyzer (SAP). Sample that treated with the mixture of nitric and sulfuric acid (HNO3/H2SO4) and functionalized with APTS gives the lowest surface area (22.07 m2/g) and pore volume (0.06 cm3/g). The pore size distribution also decreases due to the most presence of functional group onto the surface of modified MWCNT. This research paper is focusing on the effect of surface area, pore volume, and pore size distribution on the modified MWCNT.

Effect of the Presence of Water-soluble Amines on the Carbon Dioxide (CO2) Adsorption Capacity of Amine-grafted Poly-succinimide (PSI) Adsorbent During CO2 Capture

Inclusion of multi-walled carbon nanotubes (MWNTs) into tissue prior to laser therapy has the potential to enhance the selectivity and effectiveness of cancer therapy by providing greater and more controlled thermal deposition. The purpose of this study was to investigate the optical and thermal response of tissue representative phantoms containing MWNTs to optical radiation. Tissue representative phantoms 20 mm in diameter and 1 mm in thickness were created from sodium alginate. Following the inclusion of MWNTs (900 nm in length, 40-60 nm in diameter) in phantoms, the distribution of MWNTs was observed using transmission electron microscopy. A predominantly, evenly dispersed and randomly oriented distribution of MWNTs was observed with a rare presence of MWNT clustering or clumping. In order to characterize the response of MWNT inclusion on optical properties of phantoms, the transmittance and reflectance spectra of phantoms with and without MWNT inclusion were measured with a spectrophotometer over a wavelength range of 200-1400 nm. Inclusion of MWNTs in phantoms dramatically enhanced light absorption across the entire wavelength range as evidenced by a diminished transmittance and reflectance compared with phantoms without MWNTs. In order to evaluate the spatiotemporal temperature distribution associated with laser irradiation of phantoms with and without MWNTs, the temperature was measured at discrete radial distances from the center of the incident laser beam using thermocouples. The rate of temperature increase and peak temperature for phantoms containing MWNTs was much greater compared with phantoms without MWNTs at all measurement locations. In conclusion, MWNT inclusion in tissue phantoms increases the optical absorption and temperature elevation, which may enable more effective photothermal therapies of human disease utilizing lasers.

Carbon-based nanomaterials (CBN) have gained significant attention in various research disciplines due to their exceptional characteristics, including an excellent aspect ratio, substantial surface area, and superior thermal and electrical conductivity. In this study, Multi walled carbon nanotubes (MWCNT) have been selected from an array of carbon-based nanomaterials. This study focuses on exploring the use of MWCNT within the realm of organic electronics. Organic dye-based devices possess distinct advantages in comparison to their inorganic counterparts, a fact well acknowledged in the field. However, there exist certain drawbacks associated with the utilization of organic dyes in the context of being positioned between two metallic electrodes, hence establishing metal-organic interface. The charge injection process during formation of metal-organic junction is influenced by the presence of a high concentration of traps and a high injection barrier at the contact region. The improvement in charge flow at the junction and the enhancement of conductivity, as well as the reduction in threshold voltage, can be achieved by decreasing these values. From this standpoint, the inclusion of MWCNT has been implemented within the device. In the process of fabricating organic dye-based devices, two distinct organic dyes, namely Rose Bengal (RB) dye and Safranin - T dye, have been selected. Four devices were developed, with two devices being made without the inclusion of MWCNT, while the other two devices incorporate MWCNT. This study aims to examine the impact of trap energy and injection barrier on the movement of charge carriers at the interface between metal and organic materials. Additionally, it seeks to investigate any alterations in these parameters when MWCNTs are present.

The intent of this project is to determine the tensile strength of CFRP lap joint with and without introduction of multiwall carbon nano tubes (MWCNT). Specimens with lap joint were prepared by Adhesive bonding. The dimensions of the specimens were kept according to the ASTM standard D-5868. An experimental work along with FEA analysis was undertaken to identify the ultimate tensile strength and modes of failure in two different categories of adhesively bonded specimen, firstly with inclusion of different percentages of MWCNT and secondly without inclusion of MWCNT. MWCNT of 0.1% and 0.3% by weight was added to the adhesive used in creating the joint. The adhesively bonded specimens with inclusion of MWCNT showed better load bearing capacity, the highest being 86% for 0.3% MWCNT. An increment of 27% was observed in the tensile strength with the increase in percentage of MWCNT. Further the FEA analysis was carried out which proved the experimental results are well within the error range of 1%.

This research program focused on the development of fly ash derived sorbents to capture CO{sub 2} from power plant flue gas emissions. The fly ash derived sorbents developed represent an affordable alternative to existing methods using specialized activated carbons and molecular sieves, that tend to be very expensive and hinder the viability of the CO{sub 2} sorption process due to economic constraints. Under Task 1 'Procurement and characterization of a suite of fly ashes', 10 fly ash samples, named FAS-1 to -10, were collected from different combustors with different feedstocks, including bituminous coal, PRB coal and biomass. These samples presented a wide range of LOI value from 0.66-84.0%, and different burn-off profiles. The samples also spanned a wide range of total specific surface area and pore volume. These variations reflect the difference in the feedstock, types of combustors, collection hopper, and the beneficiation technologies the different fly ashes underwent. Under Task 2 'Preparation of fly ash derived sorbents', the fly ash samples were activated by steam. Nitrogen adsorption isotherms were used to characterize the resultant activated samples. The cost-saving one-step activation process applied was successfully used to increase the surface area and pore volume of all the fly ash samples. The activated samples present very different surface areas and pore volumes due to the range in physical and chemical properties of their precursors. Furthermore, one activated fly ash sample, FAS-4, was loaded with amine-containing chemicals (MEA, DEA, AMP, and MDEA). The impregnation significantly decreased the surface area and pore volume of the parent activated fly ash sample. Under Task 3 'Capture of CO{sub 2} by fly ash derived sorbents', sample FAS-10 and its deashed counterpart before and after impregnation of chemical PEI were used for the CO{sub 2} adsorption at different temperatures. The sample FAS-10 exhibited a CO{sub 2} adsorption capacity of 17.5mg/g at 30 C, and decreases to 10.25mg/g at 75 C, while those for de-ashed counterpart are 43.5mg/g and 22.0 mg/g at 30 C and 75 C, respectively. After loading PEI, the CO{sub 2} adsorption capacity increased to 93.6 mg/g at 75 C for de-ashed sample and 62.1 mg/g at 75 C for raw fly ash sample. The activated fly ash, FAS-4, and its chemical loaded counterparts were tested for CO{sub 2} capture capacity. The activated carbon exhibited a CO{sub 2} adsorption capacity of 40.3mg/g at 30 C that decreased to 18.5mg/g at 70 C and 7.7mg/g at 120 C. The CO{sub 2} adsorption capacity profiles changed significantly after impregnation. For the MEA loaded sample the capacity increased to 68.6mg/g at 30 C. The loading of MDEA and DEA initially decreased the CO{sub 2} adsorption capacity at 30 C compared to the parent sample but increased to 40.6 and 37.1mg/g, respectively, when the temperature increased to 70 C. The loading of AMP decrease the CO{sub 2} adsorption capacity compared to the parent sample under all the studied temperatures. Under Task 4 'Comparison of the CO{sub 2} capture by fly ash derived sorbents with commercial sorbents', the CO{sub 2} adsorption capacities of selected activated fly ash carbons were compared to commercial activated carbons. The CO{sub 2} adsorption capacity of fly ash derived activated carbon, FAS-4, and its chemical loaded counterpart presented CO{sub 2} capture capacities close to 7 wt%, which are comparable to, and even better than, the published values of 3-4%.

Copper (Cu) metal matrix composite (MMC) was developed with multiwall carbon nanotubes (MWCNT) as reinforcement by using powder metallurgy (PM) technique. The composition of the composites is Cu, Cu-4 wt% MWCNT, Cu-8 wt% MWCNT, and Cu-12 wt% MWCNT. The Cu and MWCNTs were blended for 6 hours in a ball mill and compacted at a 6 ton pressure to form green compacts using a 10 ton hydraulic press. Using a tubular furnace, the heat was applied at 900°C for 1.5 hours to impart strength and integrity to the green compacts. Milled composite blends were studied to analyze its characterization through SEM and EDAX analysis. Characterization studies such as SEM and EDAX confirm the presence and even dispersion of Cu and MWCNT constituents. The relative density, hardness, and ultimate compressive strength have been studied, and a remarkable improvement in properties has been obtained by the inclusion of MWCNTs. The composites reinforced by 8 and 12 wt% MWCNT were recorded with low thermal conductivity than the Cu composite reinforced by 4 wt% MWCNT. A wear study was analyzed using Taguchi technique for determining the effect caused by the wear test parameters and MWCNT content on wear rate. The optimized parameter that contributes minimum wear rate was identified as 12 wt% MWCNT content, 10 N applied load, 2 m/s sliding velocity, and 500 m sliding distance. Based on the obtained results, it could be understood that the produced composites can be utilized for various applications like relay contact springs and switchgear, rotor bars, and bus bars.

Effects of cryomilling on the structures and hydrogen storage characteristics of multi-walled carbon nanotubes

Preparation and desalination performance of multiwall carbon nanotubes

The electrically conductive regenerated silk fibroin (RSF) fiber containing multiwalled carbon nanotubes (MWNTs) was developed through wet spinning process. A general scheme used for extraction of RSF powder as biopolymer matrix for MWNTs conductive filler. The MWNTs inclusion demands for a sophisticated approach to prepare stable, exfoliated and well distributed filler in matrix solution. Dynamic Light Scattering (DLS) was utilized to show the ability of RSF in stabilizing of MWNTs throughout spinning solution. A non-Newtonian shear thinning behavior observed for RSF/MWNTs according to strong chain entanglement, whereas, the neat RSF solution shows a lower dependence on the shear rate. The scanning electron microscopy (SEM) images also confirmed the proper distribution of MWNTs as a continuous fibril media in the RSF matrix. The Fourier transform infrared spectroscopy (FTIR) demonstrated the role of MWNTs inclusion for increasing of the crystalinity compared to bare RSF fiber. The Raman spectra also confirmed the domination of RSF signatures by strong Raman bands of MWNTs most specifically in RBM region regarding to superior nanotube exfoliation. Moreover, the measurement of four-point probe electrical conductivity for different MWNTs content shows a maximum conductivity of 0.12 S/cm at percolation threshold. The higher thermal stability and greater crystalinity were also evidenced by DSC thermal analysis.

Development of effective materials for carbon dioxide (CO2) capture technology is a fundamental importance to reduce CO2 emissions. This work establishes the addition of amine functional group on the surface of activated carbon to further improve the adsorption capacity of CO2. Rice husks activated carbon were modified using wet impregnation method by introducing piperazine onto the activated carbon surfaces at different concentrations and mixture ratios. These modified activated carbons were characterized by using X-Ray Diffraction (XRD), Brunauer, Emmett and Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The results from XRD analysis show the presence of polyethylene butane at diffraction angles of 21.8° and 36.2° for modified activated carbon with increasing intensity corresponding to increase in piperazine concentration. BET results found the surface area and pore volume of non-impregnated activated carbon to be 126.69 m2/g and 0.081 cm3/g respectively, while the modified activated carbons with 4M of piperazine have lower surface area and pore volume which is 6.77 m2/g and 0.015 cm3/g respectively. At 10M concentration, the surface area and pore volume are the lowest which is 4.48 m2/g and 0.0065 cm3/g respectively. These results indicate the piperazine being filled inside the activated carbon pores thus, lowering the surface area and pore volume of the activated carbon. From the FTIR analysis, the presence of peaks at 3312 cm-1 and 1636 cm-1 proved the existence of reaction between carboxyl groups on the activated carbon surfaces with piperazine. The surface morphology of activated carbon can be clearly seen through FESEM analysis. The modified activated carbon contains fewer pores than non-modified activated carbon as the pores have been covered with piperazine.

Activated carbons prepared by the KOH activation of a hydrochar from garlic peel and their CO2 adsorption performance

Titanium dioxide protection against Al4C3 formation during fabrication of aluminum-TiO2 coated MWCNT composite

The growing demand for natural aggregates in the construction industry has motivated researchers to utilize recycled concrete aggregates (RCA) to preserve the natural resources and provide sustainable structure. However, the use of RCA in concrete applications has revealed defects in performance with low strength and rapid collapse under static and dynamic loads, respectively. Thus, the objective of present research is to improve these properties by using multi-walled carbon nanotubes (MWCNT). This study involves evaluating the fresh and hardened properties of recycled aggregate concrete (RAC) modified with different levels of MWCNT. The study involves RCA (i.e., 0 %, 25 %, 50 %, 75 % and 100 %) as replacement for natural aggregates, and MWCNT (i.e., 0.05 %, 0.1 % and 0.25 %) as weight of cement. The experimental testing consists of 240 specimens prepared from different mixtures. Workability is assessed using slump tests. Mechanical properties including static compressive strength and dynamic impact resistance are evaluated at 7 and 28 days. Experimental results show that incorporating MWCNT at all levels significantly reduces the slump values for all specimens. On the other hand, the compressive strength is increased by adding MWCNT to the concrete samples. The compressive strength of the RAC increased by as much as 70 % when modified with MWCNT. Furthermore, the inclusion of MWCNT is found to significantly increase the impact resistance of RAC specimens with percentage developments reaching approximately 11–508 % and 110–679 % at 7 and 28 days, respectively, at both first crack and failure stages. The dosage of 0.1 % MWCNT is shown to exhibit the highest percentage enhancement in impact resistance among the other nano levels. The failure patterns and cracks propagation are presented as well.

PurposeThis study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach.Design/methodology/approachThe prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable.FindingsThe surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film.Practical implicationsThe MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices.Originality/valueThe results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.