Activated carbon complex

Kobayashi, E., Sugai, M., Imajyo, S., Adsorption of arsenate ion by the zirconium(iv) oxide hydrate active carbon complex. Nihon Kagaku Kaishi 1984, 656-660. 

The overhead temperatures of both the absorber and stripper are kept as low as possible to minimise solvent carryover. A temperature of about 311 K is typically used ia the high pressure absorber. The overhead temperature ia the stripper is set by the boiling poiat of the saturated complex solution and by the operating pressure of the stripper. At a stripping pressure of 0.166 MPa (1.7 atm), a temperature of 378 Kis used. The solvent-rich gas from the stripper is cooled to recover as much solvent as possible by condensation prior to the final aromatics-recovery section. Fiaal solvent recovery is accomphshed by adsorption on activated carbon (95). 

Nickel plating solutions may contain excess iron and unknown organic contaminants. Iron is removed by peroxide oxidation, precipitation at a pH of about 5, then filtered out. The more complex, less water-soluble organic contaminants along with some trace metals are removed with activated carbon treatments in separate treatment tanks. About 5 g/L of plating-grade activated carbon is mixed in the plating solution for at least 1—2 hours, usually at warmer temperatures. 

Owing to the stability of the uranyl carbonate complex, uranium is universally present in seawater at an average concentration of ca. 3.2/rgL with a daughter/parent activity ratio U) of 1.14. " In particulate matter and bottom sediments that are roughly 1 x 10 " years old, the ratio should approach unity (secular equilibrium). The principal source of dissolved uranium to the ocean is from physicochemical weathering on the continents and subsequent transport by rivers. Potentially significant oceanic U sinks include anoxic basins, organic rich sediments, phosphorites and oceanic basalts, metalliferous sediments, carbonate sediments, and saltwater marshes. " ... 

Case 2 - The Hyde Park Landfill site, located in an industrial complex in the extreme northwest corner of Niagara, New York, was used from 1953 to 1975 as a disposal site for an estimated 80,000 tons of chemical waste, including chlorinated hydrocarbons. A compacted clay cover was installed in 1978 over the landfill and a tile leachate collection system was installed in 1979. Hazardous compounds such as ortho-, meta- and para-chlorobenzoic acid toluene ortho- and meta-chlorotoluene 3,4-dichlorotoluene and 2,6-dichlorotoluene were detected in the leachate (Irvine et al., 1984). Since 1979, the existing leachate treatment system has used activated carbon as the technology for removing organic carbon. Although... 

Keywords Flue gas denitration, NO oxidation, ammine cobalt complex, activated carbon INTRODUCTION... 

This paper presents the experimental results, with a focus on studies of the regeneration of the hexamine cobalt complex additive by using the activated carbon in a laboratory packed-bed absorber. 

The above proposed process can be expected to easily put into practice as ammonia is abuandant as the main feedstock for fertilizer. Nevertheless, there is also a problem that Co(NH3)6 is apt to be oxidized to Co(NH3)6 which is unable to form the peroxo binuclear complex and ineffective to O2 solubility enhancement, thus reaction (4) is inhibited. But Co will be relatively stable, and Co may be reduced to Co " by H2O [12]. As a result, a regenration method has also been proposed by using the activated carbon as the catalyst[7], in which Co(NH3)6 dissociation into Co " and NH3 occurs on the activated carbon surface followed by reduction of Co with H2O into Co, O2 and H. ... 

Co(NH3)6 is effective for NO absorption, and O2 can enhance NO absorption as the result of oxidation reaction. Activated carbon is also active to maintain stability of NO absorption by turning the side reaction of Co complex oxidized into Co complex backward, and the suitable regeneration conditions are obtained. A laboratory packed absorber- regenerator setup show a NO removal of more than 85% can be maitained constant. 

Complex 5 was more active than the well-known precious-metal catalysts (palladium on activated carbon Pd/C, the Wilkinson catalyst RhCl(PPh3)3, and Crabtree s catalyst [lr(cod)(PCy3)py]PFg) and the analogous Ai-coordinated Fe complexes 6-8 [29] for the hydrogenation of 1-hexene (Table 2). In mechanistic studies, the NMR data revealed that 5 was converted into the dihydrogen complex 9 via the monodinitrogen complex under hydrogen atmosphere (Scheme 4). 

Gas-phase grafting (GG) is characteristic in that gold can be deposited even on the acidic surfaces, such as activated carbon and on Si02 [27]. The vapor of gold acac complex is adsorbed on the support powder probably through the interaction of electron-rich oxygen atoms in acetylacetonate and then calcined in air to decompose it into metallic gold particles. 

Reed, B. and Nonavinakere, S., Metal adsorption by activated carbon—effect of complexing ligands, competing adsorbates, ionic strength, and background electrolyte, Sep Sci Technol, 27 (14), 1985-2000, 1992. 

CO3 species was formed and the X-ray structure solved. It is thought that the carbonate species forms on reaction with water, which was problematic in the selected strategy, as water was produced in the formation of the dialkyl carbonates. Other problems included compound solubility and the stability of the monoalkyl carbonate complex. Van Eldik and co-workers also carried out a detailed kinetic study of the hydration of carbon dioxide and the dehydration of bicarbonate both in the presence and absence of the zinc complex of 1,5,9-triazacyclododecane (12[ane]N3). The zinc hydroxo form is shown to catalyze the hydration reaction and only the aquo complex catalyzes the dehydration of bicarbonate. Kinetic data including second order rate constants were discussed in reference to other model systems and the enzyme carbonic anhy-drase.459 The zinc complex of the tetraamine 1,4,7,10-tetraazacyclododecane (cyclen) was also studied as a catalyst for these reactions in aqueous solution and comparison of activity suggests formation of a bidentate bicarbonate intermediate inhibits the catalytic activity. Van Eldik concludes that a unidentate bicarbonate intermediate is most likely to the active species in the enzyme carbonic anhydrase.460... 

Cu—C bond of the complex. Recently, activation of C02 as an r/1-C metalocarboxylate209 and photoinduced or thermal insertion of C02 into a metal-hydride bond210 have been reported. Furthermore, some metal (Zn2+, Ni2+, and Cd2+) complexes of tetraazacy-cloalkanes have been found to take up C02 easily in basic alcoholic solutions, and their structures have also been examined.211 More recently facile insertion of C02 into Rh2(/x-OH)2 to yield a carbonate complex of a rather complicated structure has been reported.212... 

---