Action Of Caustic Soda Research Articles

Modified phosphogypsum sequestrating CO2 and characteristics of the carbonation product

A method of PG carbonation to produce polymorphs of high-purity CaCO3 was proposed. The effect of experimental conditions on transformation process from PG to calcium carbonate was systematically discussed. PG transformed into granular portlandite and fibrous quartz under the action of caustic soda at room temperature for 10 min. The carbonation ratio (η) was 98.57%, and 1000 kg of PG could produce 519 kg of high-purity CaCO3 and sequestrated 228 kg of CO2. The spherical vaterite carbonation product met the relevant standards for the industrial precipitated calcium carbonate. A reaction mechanism of PG carbonation was also proposed by thermodynamic research of the gas-liquid-solid reaction. The products with a single vaterite structure, or a vaterite and calcite mixing structure or a vaterite, aragonite and calcite mixing structure were all successfully prepared. All of these indicated that the whole procedure setup of PG carbonation showed potential application for PG utilization and CO2 sequestration.

Bauxite residue issues: III. Alkalinity and associated chemistry

A detailed understanding of the complex buffering and neutralization chemistry of bauxite residue remains the key to improved management, both in terms of reduced environmental impact for current storage practices, legacy costs and for the utilization of the material as an industrial by-product for other applications. In spite of 120 years of continuous industrial production, the nature of residue and the chemistry of remediation is still poorly understood. This review brings together what is known of residue behavior and outlines the existing knowledge gaps in our understanding. It examines those aspects of the Bayer process that relate to the creation of the alkalinity in residue and discusses in detail the complex chemical reactions that govern the neutralization behavior. pH is the “master variable” in the chemistry of residue and is strongly buffered by the presence of multiple alkaline solids. The pH in untreated residue liquor (washer overflow) ranges over 9.2–12.8 with an average value of 11.3 ± 1.0. This high alkalinity is the primary reason for residue classification as a hazardous material, and in conjunction with the sodic content the primary reason that residue will not support plant life. The pH is highly buffered by the presence of alkaline solids (various hydroxides, carbonates, aluminates and aluminosilicates) that are formed by the action of caustic soda on bauxite in the Bayer process refinery. The presence of such Bayer process characteristic solids causes the acid neutralization behavior of residues to be highly complex and makes impractical the removal of alkalinity by simply washing with water. This chemistry also impacts physical properties e.g. bulk density, sedimentation rates and compaction, hydraulic conductivity, drying rates and dusting behavior, and physical strength after drying. Understanding how surface charge develops, distributes and abates in the residue mineral assemblage as a function of acid input will be paramount to understanding neutralization reactions overall, to successfully model them and eventually to implement the most effective neutralization measures that create conditions at the surface conducive to reduced environmental impact, e.g. to enable plant growth. Once this is understood a model can be constructed for the neutralization behavior of bauxite residue based on the underlying mineralogy and its relationship to overall surface charge. This is the third in a series of four reviews examining bauxite residue issues in detail.

Effect of chemical reagents on the fine structure of cellulose. Part IV. Action of caustic soda on the fine structure of cotton and ramie

AbstractAn x‐ray study has been made of the changes in lateral order that take place on the treatment of cotton and ramie with different concentrations of caustic soda at 0 and 20°C. When mercerization conditions are reached it is found that there is an increase in lateral disorder in the fibrils. The x‐ray diagrams from samples treated in the higher concentrations of caustic soda reveal a residual diffraction effect that can be interpreted in terms of a special type of cellulose sheet. This result implies one extreme of lateral disorder that is present in the fine structure of these materials. Indication is given how these lateral disorder phenomena can affect reactivity.

Function of sheets of cellulose chains in swelling reactions on cellulose

AbstractAn x‐ray investigation of the products formed by the action of caustic soda on different samples of cellulose and those formed on the decomposition of these products by aqueous reagents and alchols shows that the fundamental reacting unit is a sheet of cellulose chains, and not individual cellulose chains. Although the caustic soda can affect the relative dispositions of the chains within these sheets to some extent, it cannot separate the chains, and the products then depend on the aggregation of the cellulose sheets with or without other molecules between them. Such aggregation leads to variables products whose x‐ray diagrams can, however, show distinct reflections and be mistaken for those from more precise crystal structures. It is, therefore, important in swelling reactions to take into account the ability of the swelling agent to modify the cellulose sheets and the mode of decomposition of the complexes formed on swelling. Thus swelling with caustic soda cannot be taken as typical of all aqueous swelling reagents in its reaction towards cellulose, and the possibility with other reagents of finding cellulose I, instead of cellulose II, after a series of swelling reactions must be taken into consideration.

Effect of chemical reagents on the fine structure of cellulose. Part III. Action of caustic soda on cotton and ramie

AbstractThe changes in x‐ray orientation brought about by the treatment of cotton and ramie with caustic soda of different concentrations have been studied. With ramie the effect of the treatment is to decrease the x‐ray orientation, while with cotton the reverse is true. The cause of this difference is traced to a difference in the morphology of the two fibers rather than a difference in their fine structure.

45—A Study of the Action of Alkalis on Jute

Since the alkalis studied, with the exception of caustic soda, exert only a small solubilising effect on the constituents of jute, the action of caustic soda in particular has been investigated.The reaction of caustic soda with jute, which is very rapid in the initial stages, is almost complete after 1 hour, and an increase in reaction temperature above 40°C generally tends markedly to increase the losses in weight. The first extraction has been found to eliminate the major portion of soluble constituents, while subsequent treatments have relatively small effects. A small portion of lignin is solubilised even after a mild treatment, while the hexosan fraction remains practically unaffected by the action of cold caustic soda. A portion of xylan (5 per cent) and polyuronide (1 per cent) appears to be intimately associated in the fibre, and any attempt to solubilise this resistant fraction of the hemicelluloses results in a marked decrease in strength.The shrinkage suffered by jute in concentrated caustic soda is enhanced with increase in the concentration and decrease in temperature.A marked reduction in the wet strength of the yarn occurs even after a mild treatment with alkali, which seems to be attributable to possible changes in the yarn structure brought about by the higher swelling of the individual fibres in water.The dry strength of the yarn tends to decrease slightly with the progressive removal of hemicelluloses by the action of dilute alkali. A marked decrease (49 per cent), however, occurs after a treatment with concentrated alkali at room temperature. After a similar treatment, the loss in strength of single fibres is 25 per cent, while yarn spun from the treated fibre shows only a small reduction in quality ratio (from 76 to 69). The pronounced decrease in the strength of the treated yarn has been attributed to non-uniform distribution of applied load owing to derangement of the fibres in the yarn. The smaller decrease in the case of yarn spun from the treated fibre appears to be due to the greater number of finer fibres being effective in sharing the stress in a unit cross-section of the yarn.

Alkaloids of the Australian Rutaceae: Melicope fareana. V. The Structure of the Alkaloids

Melicopine, melicopidine, and melicopicine are shown to be members of a new group of alkaloids derived from acridine. The structure of melicopicine, 1,2,3,4-tetramethoxy-10-methylacridone (II), is deduced from data reported in earlier papers. The presence of the same 10-methylacridone skeleton in melicopidine and melicopine is established by conversion of the trimethoxyphenols obtained from them by fission of the methylenedioxy ring with methanolic potash to the respective dimethoxy-o- and p-quinones previously prepared from melicopicine. This conversion also establishes the position of the methylenedioxy group in melicopine relative to the hydroxyl group in normelicopicine. Similar considerations applied to the ethoxydimethoxyphenols show the position of the methylenedioxy group in melicopidine relative to the hydroxyl group in normelicopicine, and in this case, lead to the complete structure for the alkaloid (XIII). The action of nitrous acid on normelicopine and normelicopidine gives two hydroxymethoxyquinones isomeric with that obtained by the action of sodium carbonate on the dimethoxy-o- and p-quinones. The same two hydroxymethoxyquinones also result from the action of caustic soda on the dimethoxy-o- and p-quinones respectively. Their structures, which can be deduced from the second method of preparation, confirm the positions of the methylenedioxy group in melicopine and melicopidine relative to the hydroxyl group of normelicopicine, and prove that the hydroxyl groups in normelicopine and normelicopidine are in the same position as that in normelicopicine, but they do not make possible a choice between alternative structures for melicopine. This choice depends on the position of the hydroxyl group of the noralkaloids relative to the remainder of the acridone molecule. By consideration of the mechanism of fission of the methylenedioxy ring, the hydroxyl group of the noralkaloids is shown to be situated peri to the acridone oxygen atom, i.e. at position 4. This is confirmed by the occurrence of hydrogen bonding. Consequently the complete structural formula for melicopine is XXIII. The properties of the alkaloids and a number of the degradation products are discussed.

The Action of Caustic Soda on Cotton Cellulose

Journal of the Society of Dyers and ColouristsVolume 43, Issue 1 p. 9-12 The Action of Caustic Soda on Cotton Cellulose W. F. A. Ermen M.A., W. F. A. Ermen M.A.Search for more papers by this authorS. H. Jenkins M Sc. Tech., S. H. Jenkins M Sc. Tech.Search for more papers by this author W. F. A. Ermen M.A., W. F. A. Ermen M.A.Search for more papers by this authorS. H. Jenkins M Sc. Tech., S. H. Jenkins M Sc. Tech.Search for more papers by this author First published: January 1927 https://doi.org/10.1111/j.1478-4408.1927.tb01400.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume43, Issue1January 1927Pages 9-12 RelatedInformation

The Heat Developed by the Action of Caustic Soda on Cotton (“Mercerisation”)

The Heat Developed by the Action of Caustic Soda on Cotton (“Mercerisation”)

Action of caustic soda on cotton

Action of caustic soda on cotton

A Historical Note on the Action of Caustic Soda on Cotton, and on the Dyeing of Manganese Bronze

A Historical Note on the Action of Caustic Soda on Cotton, and on the Dyeing of Manganese Bronze