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doi: 10.1002/jctb.280360502pmid: N/A
The bulk of the work consists of a theoretical study of the possibility of submitting Umm‐Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolution of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H2SO4 (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis.
doi: 10.1002/jctb.280360503pmid: N/A
A study of the operational variables involved in the treatment of palm oil mill effluent (POME) was carried out. These included the acidic or alkaline nature of the POME discharged from the oil mills, the efficiency of the decay (or digestion) of the chemical oxygen demand (COD) contents of the POME, the economic benefits that could arise from the digested sludge and biogas and finally the net economic recovery abilities of the various treatment methods available. The chemical oxygen demand (COD) contents of the POME must be reduced to an acceptable level of 2000–3000 mg solids dm−3 of sludge before the latter can be used as a fertiliser material. In 10 days of operational periods various anaerobic digestion treatment methods gave COD reduction efficiencies of 76–96%, the batch pond anaerobic digestion mode gave an efficiency of 76.5%, the continuous pond modes 92.5–95.5% and the tank digester 93.8%. In all anaerobic operations the optimal pH values of the POME media were in the range 7.1–7.6 and a ratio of the volatile acids to the total alkalinity of the media (VA/TA) of 0.3 or less was found to enhance the performance of these digesters. Economic analyses carried out on all modes of treatment gave the following economic recovery abilities: the decanter/drier system gave a break‐even situation of 3 years, the tank digester system, 2 years, and the single stage anaerobic pond system, 6 years. The batch pond system appeared not to give a break‐even situation. Of the treatment methods examined the decanter/drier and tank digester systems were concluded to be optimal.
Fierro, Jose Luis G.; Salazar, Emilio; Legarreta, Juan A.
doi: 10.1002/jctb.280360504pmid: N/A
The adsorption of isobutene (in the temperature range 309–341K) and methacrolein (in the temperature range 296–336 K) on a Mo/(Mo+U)=0.89 catalyst were studied. The equilibrium data were analysed according to Freundlich's model. The high coverages observed at lower temperatures suggest some participation of physical adsorption in the reversible adsorption. Entropy calculations showed that these adsorbed species are best described by a mobile model which assumes bidimensional translation and two rotational degrees of freedom. Isobutene is weakly chemisorbed, producing reversible species which were identified as a π‐complex formed by interaction with surface OH groups through π‐electrons (infrared bands at 1655, 1615, 1470 and 1375 cm−1), and only a small fraction of isobutene interacts strongly via lattice oxygen forming intermediate species in the oxidation reaction. However, in the presence of oxygen at 523 K a majority of the surface species are strongly held by the surface (infrared bands at 1775, 1723, 1610, 1460 and 1350 cm−1 associated to a methacrylic complex and bands at 1590 and 1538 cm−1 of carbonate‐carboxylate species).
Phadke, Ravindra Chintaman; Rangnekar, Dinesh Wamanrao
doi: 10.1002/jctb.280360505pmid: N/A
Synthesis of 2‐triazolylthiazolo[4,5‐b]quinoxaline derivatives was achieved by diazotisation of 2‐aminothiazolo[4,5‐b]quinoxaline and its 6‐nitro derivative using orthophosphoric acid and sodium nitrite with a trace of nitric acid, coupling with suitable aromatic amines and subsequent cyclisation of the resulting ortho amino azo compounds. Diazotisation of 2,6‐diaminothiazolo[4,5‐b]quinoxaline with concentrated hydrochloric acid and sodium nitrite and subsequent coupling and cyclisation resulted in the 6‐triazolylthiazolo[4,5‐b]quinoxaline derivatives. These compounds were applied on polyester as fluorescent disperse dyes.
Niwa, Shu‐Ichi; Mizukami, Fujio; Isoyama, Shigemi; Tsuchiya, Tohru; Shimizu, Kazuo; Imai, Sumi; Imamura, Juichi
doi: 10.1002/jctb.280360506pmid: N/A
Ruthenium catalysts were prepared in different alcohols by a chemical mixing technique, characterised by the preparation of a homogeneous solution containing catalyst components, and the uniform coagulation of the solution through hydrolysis. The technique has the potential for controlling the surface area of the catalysts and for making them porous. The ruthenium catalysts were much more effective for the partial hydrogenation of benzene to cyclohexene (maximum cyclohexene yield, 31.4%) in the absence of any poison such as alkali metal hydroxide or transitional metal sulphate in the reaction solution.
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