G . H evesy has written that [6] 1 " In view of the I.great similarity b etween hafnium and zirconium, i t ris hardly possible to separate these two elements in a lsingle operation ." A simple one-step separation c adequ a te for analytical work has still to be developed for hafnium-ziTconium mixtures, although recent work employing ion exchange has developed suitable methods for the separation...

Silica sulfuric acid is employed as solid acid catalyst for the clean and less hazardousprotection of carbonyl compounds as 2,4-dinitrophenylhydrazone under solvent-free conditions.

A green and convenient method for the synthesis of 14-aryl-14H-dibenzo[a,i]xanthene-8,13-diones and spiro[dibenzo[a,i]-xanthene-14,3'-indoline]-2',8,13-triones in the presence of a catalytic amount of cellulose sulfuric acid (CSA) as an efficient biopolymer-based catalyst under solvent-free conditions at 100 °C is described. The condensation reactions of β-naphtol, 2-hydroxynaphthalene-1,4-dion...

molybdate sulfuric acid (msa) has been prepared and used as catalyst for the biginelli synthesis of some quinazolinones/thiones under solvent-free conditions. the catalyst loading is low and it shows recyclability. this method has advantages such as avoidance of the organic solvents, high yield of pure products, short reaction times and operational simplicity.

Dilute oxalic acid pretreatment was applied to maple wood to improve compatibility with downstream operations, and its performance in pretreatment and subsequent enzymatic hydrolysis was compared to results for hydrothermal and dilute hydrochloric and sulfuric acid pretreatments. The highest total xylose yield of ∼84% of the theoretical maximum was for both 0.5% oxalic and sulfuric acid pretrea...

While it is well established that organics compose a large fraction of the atmospheric aerosol mass, the mechanisms through which organics are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds with carbonyl groups have recently been suggested as important pathways for transfer of volatile organics into acidic aerosols. In the present study, we...

Infrared extinction spectra in the 3-5-microm and 7-13-microm atmospheric window regions have been obtained for smokes of petroleum oil, sulfuric acid, and phosphoric acid of varying droplet concentration and for water fogs. Spectra were also obtained at 0.36-2.35microm for petroleum oil and sulfuric acid smokes. Experimental results were compared, for sulfuric acid and water aerosols, to calcu...

The chemical composition and aluminum speciation of sludge incineration residue (SIR) were determined. Cementation of aluminum from sulfuric acid solution using SIR was studied. The results showed that acid-soluble inorganic aluminum was the predominant component in the sludge, and the total leached aluminum increased from 62.2% to 92.9% after incineration. Sulfuric acid dosage and reaction tim...

a green and convenient method for the synthesis of 14-aryl-14h-dibenzo[a,i]xanthene-8,13-diones and spiro[dibenzo[a,i]-xanthene-14,3'-indoline]-2',8,13-triones in the presence of a catalytic amount of cellulose sulfuric acid (csa) as an efficient biopolymer-based catalyst under solvent-free conditions at 100 °c is described. the condensation reactions of β-naphtol, 2-hydroxynaphthalene-1,4-dion...