Microporous activated carbons prepared from palm shell by thermal activation and their application to sulfur dioxide adsorption

Textural characterization of activated carbons prepared from palm shell by thermal activation with carbon dioxide (CO(2)) gas is reported in this paper. Palm shell (endocarp) is an abundant agricultural solid waste from palm-oil processing mills in many tropical countries such as Malaysia, Indonesia, and Thailand. The effects of activation temperature on the textural properties of the palm-shell activated carbons, namely specific surface area (BET method), porosity, and microporosity, were investigated. The activated carbons prepared from palm shell possessed well-developed porosity, predominantly microporosity, leading to potential applications in gas-phase adsorption for air pollution control. Static and dynamic adsorption tests for sulfur dioxide (SO(2)), a common gaseous pollutant, were carried out in a thermogravimetric analyzer and a packed column configuration respectively. The effects of adsorption temperature, adsorbate inlet concentration, and adsorbate superficial velocity on the adsorptive performance of the prepared activated carbons were studied. The palm-shell activated carbon was found to have substantial capability for the adsorption of SO(2), comparable to those of some commercial products and an adsorbent derived from another biomass.     

Adsorption of NH3 onto activated carbon prepared from palm shells impregnated with H2SO4

Adsorption of ammonia (NH3) onto activated carbons prepared from palm shells impregnated with sulfuric acid (H2SO4) was investigated. The effects of activation temperature and acid concentration on pore surface area development were studied. The relatively large micropore surface areas of the palm-shell activated carbons prepared by H2SO4 activation suggest their potential applications in gas adsorption. Adsorption experiments at a fixed temperature showed that the amounts of NH3 adsorbed onto the chemically activated carbons, unlike those prepared by CO2 thermal activation, were not solely dependent on the specific pore surface areas of the adsorbents. Further adsorption tests for a wide range of temperatures suggested combined physisorption and chemisorption of NH3. Desorption tests at the same temperature as adsorption and at an elevated temperature were carried out to confirm the occurrence of chemisorption due to the interaction between NH3 and some oxygen functional groups via hydrogen bonding. The surface functional groups on the adsorbent surface were detected by Fourier transform infrared spectroscopy. The amounts of NH3 adsorbed by chemisorption were correlated with the contents of elemental oxygen present in the adsorbents. Mechanisms for chemical activation and adsorption processes are proposed based on the observed phenomena.     

Electrochemical and Transport Characteristics of Membrane Systems in the Electronanofiltration Separation of Solutions Containing Ammonium Nitrate and Potassium Sulfate

Russian Journal of Electrochemistry - Electrochemical and transport characteristics of systems equipped with OPMN-P and OFAM-K membranes during operation in electronanofiltration cell are studied...     

Synthesis and characterization of novel conjugated polymers based on 3-cyclobutene-l,2-dione moiety

Three novel conjugated polymers bearing 3,4-bis(4-hexylthiophen-2-yl)-3-cyclobutene-1,2-dione unit in their main chain have been synthesized successfully in good yields through Suzuki or Stille coupling reaction.Their molecular structures have been confirmed by FT-IR,~1H NMR and ~(13)C NMR.All these copolymers exhibit broad and strong absorption bands in UV-vis region,and their optical band gaps are calculated to be 1.6-2.0 eV.suggesting that they have good coverage with the solar spectrum.These polymers...     

Surface characterizations of spin-coated films of ethylcellulose and hydroxypropyl methylcellulose blends

Films of pure ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) polymers and EC/HPMC blends were prepared from solutions by spin coating where isopropyl alcohol (IPA), water, and IPA/water cosolvent were used as solvents. Surface structures of the films were investigated using optical microscopy, atomic force microscopy (AFM), and Raman mapping and spectroscopy. For the films prepared from EC/HPMC blend solutions using the IPA/water cosolvent, different domain structures such as islands or pits and phase separation between EC and HPMC were observed by optical microscopy and AFM. The nature of the polymer components on the surface of the films was identified by Raman mapping and spectroscopy. Experimental results also indicated that polymer composition, solvent, and temperature during spin coating had significant impacts on surface structures of the films.     

Simultaneous analysis of Cu and Pb as ABEDTA complexes in Rhizoma coptidis by capillary electrophoresis coupled with solid phase extraction

A novel capillary electrophoresis method for simultaneous determination of Cu and Pb has been developed in this paper.Cu（Ⅱ） and Pb（Ⅱ） ions were reacted with ABEDTA to form complex to achieve an ideal sensitivity of heavy metal complexes.The digestion solution of Rhizoma coptidis drug sample was purified by neutral Al₂O₃ column chromatography and the chromatographic behavior of metal-L complexes was investigated.The calibration curve was linear in the range of 5-60μg/mL for Cu²⁺ and 5-25μg/mL for Pb²⁺ with the correlation coefficients 0.9970 and 0.9972 for each（n = 5）.The average recoveries were 86.2%for Pb and 90.1%for Cu,while the relative standard deviations were 5.1%and 3.6%respectively.The method was successfully applied to determine Cu and Pb in R.coptidis drug samples.     

Polyelectrolytes as new matrices for secondary ion mass spectrometry

Significant enhancements in ion yields in time-of-flight secondary ion mass spectrometry (TOF-SIMS) are observed when water-soluble analytes are mixed with a polyelectrolyte, e.g., poly(diallyldimethylammonium chloride) or poly(sodium 4-styrenesulfonate), and then deposited in the layer-by-layer method on a surface. This previously unobserved effect is demonstrated for 5-chloro-8-methoxyquinoline appended diaza-18-crown-6, 5-(2-aminoethoxy)methyl-5-chloro-8-methoxyquinoline appended diaza-18-crown-6, acridine, 9-anthracenecarboxylic acid, and ferrocenecarboxylic acid. By optical ellipsometry film thicknesses range from ca. 5-20 angstroms. X-ray photoelectron spectroscopy shows significantly less analyte in the polyelectrolyte-analyte films than in the neat analytes. However, TOF-SIMS generally shows significant enhancements in ion yields from the polyelectrolyte films compared with either the neat compounds or the compounds solubilized with acid or base and then dried on a surface. These significant enhancements in ion yields also appear to extend to analyte fragments and cationized molecular species. Some enhancement is also observed for dried droplets of analytes mixed with a polyelectrolyte on surfaces.     

Antibacterial ultrafiltration membrane with silver nanoparticle impregnation by interfacial polymerization for ballast water

Interfacial polymerization technology was employed to immobilize silver (Ag) nanoparticles on the surface of commercial polyethersulfone (PES) membrane to develop antibacterial and antifouling ultrafiltration membrane. Ag nanoparticles were prepared from the reduction of silver nitrate (AgNO₃) by sodium borohydride in the presence of polyethyleneimine (PEI) as the stabilizer. The encapsulated Ag nanoparticles in the PEI solution were embedded into the PEI membrane when trimesoyl chloride solution was used to crosslink the PEI solution with the PES membrane, forming Ag-polyamide (PA) networks through the interfacial polymerization reaction. Experimental results showed that the membrane prepared with 50 mmol/L of AgNO₃ and 20 mmol/L of PEI had the optimized antibacterial effect against Escherichia coli. Bacterial concentration and species were also investigated. Exiguobacterium aestuarii and Staphylococcus aureus which are gram-positive bacteria, needed significantly more time for the Ag-PA/PES membrane to kill the bacteria completely when compared to E.coli and Vibrio coralliilyticus which are gram-negative bacteria. This study showed that Ag nanoparticles impregnated in membrane surfaces were 100% effective in killing various types of marine bacteria and bacteria in the seawater collected off Sentosa Island in Singapore. These membranes exhibit excellent antibacterial and antifouling properties which can be used to kill bacteria in ballast water and seawater.