Presence Of High Surface Area Research Articles

Removal of Pb(II) ion by activated carbon synthesised from Musa Acuminate stem waste: surface properties, kinetics, adsorption mechanism, and reusability

ABSTRACT We present the synthesis of Activated Carbon (AC) by pyrolysis of Banana (Musa Acuminate) Stem Waste (BSW), and the ability of obtained AC for adsorptive removal of Pb(II) ions from water. Importantly, pyrolysis was performed at 750°C for 2.0 h in the presence of high surface area producing chemical activators such as NaOH, LiOH, H3PO4, ZnCl2, and KOH. BET-surface areas of AC produced with activators NaOH, LiOH, H3PO4, ZnCl2, and KOH were determined to be 908, 1531, 1670, 2245, and 2485 m2 g−1, respectively. Pore volume ascending order was determined as 0.59 (NaOH) < 0.68 (LiOH) < 0.86 (H3PO4) < 0.97 (ZnCl2) <1.18 (KOH) cm3 g−1. SEM and TEM images revealed the porous nature of the ACs. ACs produced with H3PO4, ZnCl2, and KOH exhibit type I adsorption isotherms, indicating their microporous nature. ACs prepared with NaOH and LiOH exhibit type II adsorption isotherms, indicating their macroporous nature. X-ray diffraction, X-Ray photoelectron, and Raman spectroscopy analysis revealed the graphitic structure of ACs. Pb(II) ion adsorption onto ACs surface obeyed the Langmuir model. It was found that the Pb(II) adsorption capacities of the ACs produced with NaOH, LiOH, H3PO4, ZnCl2, and KOH as the chemical activators were 220, 283, 326, 329, and 435 mg g−1, respectively, at the optimised conditions (pH = 6.6, contact time = 100 min, [ACs] = 0.125 g L−1, at 30°C). The interaction between surface functional groups of ACs and Pb(II) ions was confirmed by X-Ray photoelectron and FT-Infrared spectroscopy. The negative values of ΔGo and ΔHo reveal that the Pb(II) ion adsorption onto the ACs surface is spontaneous and exothermic. The Pb(II) ion adsorption capacity increased with an increase in BET-SA and pore volume of ACs, with AC obtained from BSW with KOH exhibiting the highest adsorption capacity of 435 mg g−1. Thus, the study highlights BSW, agricultural biomass waste is a low-cost and abundantly available carbon precursor to synthesise potential AC adsorbent for water treatment.

Noble metal (Pd, Pt and Rh) incorporated LaFeO3 perovskite oxides for catalytic oxidative cracking of n-propane

Noble metals (Pd, Pt and Rh) incorporated LaFeO3 (LaFe) perovskite oxide nanostructures were synthesized by adapting hydrothermal synthesis method. The synthesized materials were used as catalysts for production of olefins via oxidative cracking of n-propane. The bare LaFe sample exhibited n-propane conversion of 18% with 42% olefins selectivity at reaction temperature of 600 °C. Substantial increase in n-propane conversion and olefins selectivity was perceived after incorporation of Pd, Pt and Rh in LaFe framework. The LaFe sample incorporated with Rh exhibited superior oxidative cracking performance (85% conversion of n-propane and 79% olefins selectivity) at optimized reaction conditions. A thorough characterization of synthesized catalysts was performed using various characterization techniques to obtain a correlation between the structural properties of Pd, Pt and Rh incorporated LaFe perovskite nanostructures and their catalytic activity in olefin production. The characterization results indicated that Rh and Pt species were expelled from the bulk LaFe framework and dispersed over the surface, while Pd species were strongly interacted with LaFe and occluded inside the LaFe framework. It appears that presence of expelled Rh and Pt species on the LaFe surface are responsible for better redox properties of LaFeRh and LaFePt samples. The highest oxidative catalytic cracking activity of LaFeRh sample is due to presence of high surface area, easily reducible and great number of adsorbed oxygen moieties. Catalyst durability test results indicated that Rh incorporated LaFe sample possessed stable oxidative cracking activity for 72 h without considerable loss in performance

Exceptionally Stable Microporous Organic Frameworks with Rigid Building Units for Efficient Small Gas Adsorption and Separation.

Three microporous organic frameworks (hereafter denoted as MPOF-Ads) based on a rigid adamantane core have been successfully synthesized via Sonogashira-Hagihara polycondensation coupling in high yields, 83.7-94.6%. The obtained amorphous MPOF-Ads networks have high Brunauer-Emmett-Teller surface areas (up to 737.3 m2 g-1), narrow pore size distribution (0.95-1.06 nm), and superior thermal (the initial decomposition temperature T5% under an N2 atmosphere can reach 410 °C) and chemical stability (no apparent degradation in common organic solvents or strong acid/base solutions after 7 days). At 273 K and 1.0 bar, these MPOF-Ads networks present good uptake capacities for small gas molecules (13.9 wt % CO2 and 1.66 wt % CH4) for which the presence of high surface area, predominant microporosity, and narrow pore size distribution are beneficial. In addition, the as-prepared MPOF-Ads networks possess moderate isosteric heats for CO2 (Qst = 19.5-30.3 kJ mol-1) and show desired CO2/N2 and CO2/CH4 selectivity (36.3-38.4 and 4.1-4.3 based on Henry's law and 17.88-24.92 and 4.24-5.70 based on ideal adsorbed solution theory, respectively). With the demonstrated properties, the synthesized MPOF-Ads networks display potential for small gas storage and separation that can be used in harsh environments because of their superior physical and chemical stability.

Rapid and efficient recovery of silver with nanoscale zerovalent iron supported on high performance activated carbon derived from straw biomass

High performance activated carbon (HPAC) supported nanoscale zerovalent iron (nZVI) was prepared and used for recovery of silver. This composite material was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The removal amount of Ag+ increased with pH values and temperature. The removal process achieved equilibrium within 40 min and the maximum removal capacity was 986.5 mg/g at 298 K. The composite material showed fast adsorption rate and high adsorption capacity because the presence of high surface area activated carbon could effectively inhibit aggregation of nanoscale zerovalent iron, thus enhancing its reactivity. The Ag+ removal followed pseudo-second-order kinetic model and Langmuir isotherm model. XPS and XRD characterizations were performed to elucidate removal mechanism. It could be concluded that both coordination adsorption and reductive precipitation contributed to removal of Ag+ on the nZVI/HPAC.

Graphene- and Graphene Oxide-Based Nanocomposite Platforms for Electrochemical Biosensing Applications.

Graphene and its derivatives such as graphene oxide (GO) and reduced GO (rGO) offer excellent electrical, mechanical and electrochemical properties. Further, due to the presence of high surface area, and a rich oxygen and defect framework, they are able to form nanocomposites with metal/semiconductor nanoparticles, metal oxides, quantum dots and polymers. Such nanocomposites are becoming increasingly useful as electrochemical biosensing platforms. In this review, we present a brief introduction on the aforementioned graphene derivatives, and discuss their synthetic strategies and structure–property relationships important for biosensing. We then highlight different nanocomposite platforms that have been developed for electrochemical biosensing, introducing enzymatic biosensors, followed by non-enzymatic biosensors and immunosensors. Additionally, we briefly discuss their role in the emerging field of biomedical cell capture. Finally, a brief outlook on these topics is presented.

Morphology dependent resonance modes in highly porous TiO2 microspheres

Micro and nano structures of titanium dioxide (TiO2) are well-known for their photocatalytic application. High surface area and high light scattering efficiency in such structures enhance their photocatalytic activity. The present work explores the possibility of enhancing photocatalytic activity through mesoporous TiO2 spheres by exploiting the coexistence of high porosity and morphology dependent resonance (MDR) modes. A controlled synthesis of TiO2 spheres with nano-crystalline grains of anatase phase and high surface area of about 96 m2/g has been successfully accomplished leading to mesoporous particles with uniformly distributed pores of small diameters much less than the wavelength of incident light. Despite the high porosity, MDR modes are observed in the photoluminescence spectrum of a single sphere. As inclusion of pores may produce significant changes in the refractive index (RI) of the resonator, and as the quality and density of the modes depend on the RI of the resonator, it is important to have a procedure to determine the RI of the resonator as well as to characterize the MDR modes. An iterative procedure that is quite general is presented for mode identification and for the determination of the porosity-induced reduction in the RI and for ascertaining the presence of chromatic dispersion. The presence of high surface area as well as of MDR modes of reasonably high Q-factor makes these particles promising for photo electrochemical applications.

Synthesis of Guar gum Propionate Nanoparticles for Antimicrobial Applications

Biopolymer guar gum (GG) is available from the seed endosperm of annual legume plant Cyamopsis tetragonoloba. The surface exposed free hydroxyl groups in GG were decorated with propionate esters. The base catalyzed formylation reaction prompted introduction of propionate groups. The surfactant free water dispersible and self-assemble propionate nanoparticles were developed using a facile solvent-shifting method. The FTIR, XRD, 13CNMR, DLS and TEM studies confirmed newly derivatized polymeric nanomaterial. The spherical shaped ouzo particles were effective for fungus and bacteria contact killing. This was considered due to the presence of high surface area and propionate moieties.

Promoting deoxygenation of triglycerides via Co-Ca loaded SiO2-Al2O3 catalyst

Triglycerides and fatty acid derivatives can be converted to hydrocarbon-grade green diesel that are entirely fungible to the fossil fuels. In the present study, deoxygenation (DO) process of triolein was studied by using mesoporous SiO2-Al2O3 supported Co-Ca catalyst. The presence of active metals (Co-Ca) showed high DO activity exclusively via decarboxylation/decarbonylation (deCOx) pathways with maximum hydrocarbon n-(C8-C20) yield of 73%, and high selectivity of n-C15 and n-C17 fractions. This results suggested the acid-base active sites of catalyst provide selective deCOx pathway of triglycerides structure. In additional, the presence of high surface area of Co-Ca/ SiO2-Al2O3 enhance the metal dispersion for better accessment of large molecular reactant with catalyst during DO process. An optimum Co metal content (10 wt.%) for deCOx reaction was observed, while an excess Co content is not preferable due to tendency of cracking effect. The efficiency of Co-Ca/SiO2-Al2O3 was investigated by using non-edible feedstock (e.g. Ceiba oil and Sterculia oil) along with catalyst stability study were carried out. Resulst also indicated that degradation of DO activity was due to the formation of coke.

Synthesis of Fe3O4 modified mesoporous silica hybrid for pH-responsive drug delivery and magnetic hyperthermia applications

The chemotherapy combined with thermotherapy is greatly considered in clinical applications for cancer treatment. The fabrication of nanomaterials with multifunctionality is an attractive approach to be utilized in cancer therapy. In this work, we report the synthesis of dopamine-urea organosilane (DPU) integrated mesoporous silica material in which the magnetic Fe3O4 nanoparticles were grown onto the outer surface of the mesoporous silica nanoparticles via Fe3O4-dopamine complexation method. The mesoporous structural characterization results revealed that the synthesized Fe3O4@DPU@MSH materials had high surface area (386 m2/g), large pore size (4.5 nm) and uniform particles in which the magnetic Fe3O4 nanoparticles were grown onto the outer surface of the mesopore walls with the particles size about 5–10 nm. Because of the existence of Fe3O4 nanoparticles onto the outer surface of the Fe3O4@DPU@MSH material, the sample shows superparamagnetic properties and high magnetic hyperthermia ability in the presence of applied magnetic field. Furthermore, owing to the presence of high surface area, the Fe3O4@DPU@MSH shows high drug loading capacity, and pH-responsive and temperature-accelerated drug release efficiency. In addition, the MTT assay analysis and the intracellular uptake study results support that the synthesized Fe3O4@DPU@MSH material is biocompatible. Therefore, the Fe3O4@DPU@MSH material would be a promising material for drug delivery and magnetic hyperthermia applications in cancer therapy.

Facile synthesis of mesoporous carbon from furfuryl alcohol-butanol system by EISA process for supercapacitors with enhanced rate capability

A smart, efficient and cost-effective strategy using modified evaporation induced self-assembly (EISA) is employed to synthesize mesoporous carbon (MC) with excellent textural parameters. Furfuryl alcohol is utilized as an alternative source of carbon precursor for the first time in EISA process in place of conventional EISA precursor, namely resol. Further n-Butanol, used as a co-structure directing agent during synthesis plays a crucial role in formation of a high surface area mesoporous carbon. The resulting carbon synthesized by modified EISA process shows a high specific surface area with large pore volume and more of ordered graphitic carbon. Wettability studies reveal that the surface functionalized mesoporous carbon film surface exhibits superior hydrophilic properties in comparison with non-functionalized mesoporous carbon film surface. It delivers a high specific capacitance of 151 F g−1 at a high current density of 50 A g−1 and shows excellent rate capability with 93% capacitance retention. It also exhibits good cyclic stability with capacitance retention of 96% after 10,000 cycles and delivers a stable energy density of 2.7 W h kg−1 by retaining a power density of 2516 W kg−1. The excellent electro-chemical performance of mesoporous carbon reported in the present study is attributed to the presence of high surface area of MC with large interconnected mesopores that allows unhindered flow of the electrolyte ions to the active surface sites. Benchmark studies reveal that the electro-chemical performance of mesoporous carbon being reported in this study is better than carbon electrode based commercial supercapacitors. Thus, the simple and unique strategy employed in the present study can be extended to synthesize carbon materials for other energy storage applications.

Nano-grained SnO2/Li4Ti5O12 composite hollow fibers via sol-gel/ electrospinning as anode material for Li- ion batteries

The high capacity of SnO2 (tin oxide) and high rate capability of Li4Ti5O12 (lithium titanate, LTO) were pooled together for engineering a composite Li ion anode material in hollow fiber edifice by sol-gel/electrospinning. The electrospun porous precursor composite hollow fibers (CHFs) were heat treated either in air (SnO2/LTOA) or argon (SnO2/LTOAr) atmosphere to control grain size, porosity and presence of Ti3+ content. The morphological study performed using Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed smaller grain size (5–10 nm) for SnO2/LTOAr CHFs. Further, X-Ray Diffraction and X- Ray Photoelectron Spectroscopy studies illustrated a significant variation in the crystallinity and the elemental oxidation states in these CHFs respectively. Brunauer-Emmett-Teller measurements exposed the presence of high surface area and pore volume in SnO2/LTOAr CHFs. Further, the half-cell galvanostatic charge-discharge performances of SnO2/LTOAr CHFs at 1 C rate revealed a stable specific capacity of 300 mA h/g for 110 cycles with 90% capacity retention. The stable and high capacity of SnO2/LTOAr CHFs were corroborated to the presence of smaller grain size, high porosity and conductive Ti3+ providing faster lithium ion diffusion when compared to SnO2/LTOA CHFs. Electrochemical Impedance Spectroscopy study confirmed low impedances in SnO2/LTOAr CHFs due to low charge transfer and electrolyte resistances. Moreover, Li ion full-cell study performed using LiFePO4 (LFP) cathode (3 V), delivered a specific capacity of 230 mAh/g at 0.1 C rates. The excellent electrochemical performance of SnO2/LTOAr CHFs in both half-cell and full-cell modes illustrated the significance of sol-gel/electrospinning in synthesizing high performance Lithium ion batteries in a cost effective and scalable way.

Conversion of municipal solid waste incineration bottom ash to sorbent material: Effect of ash particle size

Conversion of municipal solid waste incineration bottom ash (IBA) to sorbent material can provide an alternative route for the re-utilization of IBA and improve the sustainability of waste incineration technology. Alkaline hydrothermal treatment was adopted in this study for IBA conversion with an emphasis on the effect of IBA particle size. The converted product was determined to contain sodium aluminum silicon phosphorus oxide hydrate (Na13Al24Si13P11O96(H2O)16), katoite (Ca3Al2(SiO4)(OH)8), and other unconverted materials. It is found that IBA of small particle size contains low Si content and promotes the conversion reaction. The presence of high surface area in small particles also facilitates the contact with reagent solution and favors conversion. A reduction in particle size and an increase in surface area were found after hydrothermal conversion. The converted product was adopted as sorbent material and demonstrated promising performance for pollutants (organic dye and heavy metal ions) removal from water. An increase in the surface area of the converted product favored dye adsorption, while an increase in exchangeable cations was found to improve the heavy metal ion removal efficiency. Sorbent converted from IBA in the size range of 0.212–0.6mm was found to show the highest dye removal efficiency, while sorbent obtained from IBA having particle size < 0.212mm performed the best for heavy metal ions adsorption. The adsorption of pollutants was also investigated by isotherm study. The adsorption process was found to follow Langmuir model, indicating that the process was dominated by chemisorption.

ChemInform Abstract: Synthesis of Pyrimidine Derivatives from Three‐Component Reaction of Malononitrile, Aldehydes and Thiourea/Urea in the Presence of High Surface Area and Nanosized MgO as a Highly Effective Heterogeneous Base Catalyst.

AbstractThe new method is more convenient compared to alternative ways, because it needs shorter reaction times, allows straightforward product isolation, and provides higher yields.

Synthesis of Pyrimidine Derivatives from Three-component Reaction of Malononitrile, Aldehydes and Thiourea/Urea in the Presence of High Surface Area and Nanosized MgO as a Highly Effective Heterogeneous Base Catalyst

The three-component reaction of malononitrile, aldehydes and thiourea/urea, is applied to the formation of pyrimidine derivatives. The reaction occurs at best in EtOH at reflux, in the presence of high surface area and nanosized MgO. This methodology is more convenient to compare with alternative ways because it needs shorter reaction times, allows straightforward product isolation, and provides higher yields.

ChemInform Abstract: A Convenient One‐Pot Synthesis of New Chromeno[3,4‐c]chromene and Chromeno[3,4‐c]pyridine Derivatives in the Presence of High Surface Area of Magnesium Oxide.

AbstractThe MgO is employed as heterogeneous base catalyst for the one‐pot three component reaction to produce the title heterocycles.

A convenient one-pot synthesis of new chromeno[3,4-c]chromene and chromeno[3,4-c]pyridine derivatives in the presence of high surface area of magnesium oxide

Abstract In this investigation a new strategy involves the one-pot, three-component reaction of malononitrile, salycilaldehyde and phenol derivatives in the presence of high surface area of MgO is extended to the formation of chromeno[3,4-c]chromene derivatives in good to excellent yields in a short reaction time. Also, the three component reactions of an aldehyde such as salycilaldehyde and ketones with malononitril for the formation of chromeno[3,4-c]pyridines are investigated.

LiMBO3 (M=Fe, Mn): Potential Cathode for Lithium Ion Batteries

AbstractRecently discovered borates, LiMBO3 (M=Fe, Mn), share similarities with LiFe(Mn)PO4. They are polyanion structures, contain extractable lithium and suffer from low electronic conductivity. They are attractive to replace expensive, less abundant redox metals in current use in cathodes with environmentally friendly iron or manganese. Phosphate or borate groups adjacent to the redox active metal increase the voltage of the redox couple through an inductive effect. The LiFeBO3 discharge curve shows a pseudo-plateau around 2.6 V for the Fe(II) / Fe(III) couple. This study brings to bear techniques to improve electrode conductivity to produce LiMBO3 composite electrodes thus allowing access to some of the high, theoretical specific capacity. At low current, up to 70 percent of lithium could be extracted from LiFeBO3 that was prepared in the presence of high surface area, highly electrically conductive carbon black. Attempts to improve the cathode properties of LiMnBO3 were less successful.

Physicochemical characteristics and biological effects of nickel oxides.

Ten nickel oxides and nickel-copper oxides, which all contained NiO (bunsenite) as the predominant crystalline phase, were assayed as follows: in vitro dissolution tests in water and body fluids; in vitro phagocytosis tests in Chinese hamster ovary and C3H-10T1/2 cells; morphological transformation and cytotoxicity tests in cultured Syrian hamster embryo (SHE) cells; erythropoiesis stimulation assay by intrarenal administration to Fischer-344 rats; and scoring the renal histopathologic responses in rats killed 3 months post-injection. The test compounds differed substantially in their biological effects when tested in the various experimental systems. Based upon highly significant concordance of ranked results in the assays (P less than 0.001), six colligative biological attributes of the compounds were identified: (i) dissolution half-times in rat serum and renal cytosol; (ii) phagocytosis by C3H-10T1/2 cells; (iii) morphological transformation of SHE cells; (iv) erythropoiesis stimulation in rats; (v) induction of tubular hyperplasia in rat kidneys; and (vi) induction of arteriosclerosis in rat kidneys. Strong rank correlation (P less than 0.01) between results of the cell transformation and erythropoiesis stimulation assays is especially notable, since the compounds were tested by blind protocols in independent laboratories. The presence of high surface area and demonstrable Ni(III) were two physicochemical characteristics that were associated with the greatest biological effects of nickel oxides.

Disassociation of conjugated proteins in the presence of porous glass.

AbstractThe disassociation of hemoglobin in saline solution in the presence of high surface area, powdered, porous glasss was determined. A porphyrin‐protein conjugate was disassociated at the porphyrin‐protein bond. No hydrolysis was observed at the peptide bond.

Catalytic hydrogenation—I: The reaction of platinum metal salts with sodium borohydride—new active platinum metal catalysts for hydrogenation

The treatment of Pt metal salt solutions with sodium borohydride results in the formation of finely divided black precipitates. Certain of these precipitates ar active catalysts for the hydrolysis of sodium borohydride. SomePt, Pd and Rhare active catalysts for the hydrogenation of olefins. If the precipitation is carried out in the presence of high surface area supports such as activated carbon, these materials show even greater activity. The Pt catalyst is remarkably active as a catalyst for the hydrogenation of a large variety of olefins; Pd, on the other hand, shows a marked sensitivity toward olefin structure. Rates of reaction were followed in a novel way, using a standard solution of sodium borohydride added to acid to supply pure hydrogen as required to maintain the pressure.