The Classification and Analysis of Ancient Calcareous Materials

1966 ◽  
Vol 31 (6) ◽  
pp. 875-878 ◽  
Author(s):  
Edwin R. Littmann
Keyword(s):  
Carbon Dioxide ◽  
Organic Matter ◽  
Analytical Procedure ◽  
Raw Materials ◽  
Iron Compounds ◽  
Systematic Classification ◽  
Mild Conditions ◽  
Sources Of Error ◽  
Calcium And Magnesium

AbstractIn the present paper a systematic classification of ancient calcareous materials has been proposed which more closely defines limestone in terms of the ratio of calcium to magnesium present. The same classification may be applied to mortars and plasters to characterize the raw materials from which they were made. The classification includes "pure" calcium and magnesium minerals and any combination of the two.A new analytical procedure has been devised which eliminates the major sources of error in a previously used method and consists of first igniting the sample to remove all organic matter and most of the carbon dioxide and to oxidize any iron compounds to the ferric state. This is followed by solution of the sample under mild conditions and volumetrically determining the calcium and magnesium under conditions which eliminate the effect of any dissolved impurities.

Sustainable regional development as a problem of managing the socio-economic system

Ergodesign ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 58-62
Author(s):  
Alexander Anishenko ◽  
Tatyana Krotenko ◽  
Dmitriy Erokhin
Keyword(s):  
Sustainable Development ◽  
Regional Development ◽  
Economic System ◽  
Raw Materials ◽  
Resource Model ◽  
Systematic Analysis ◽  
Development Control ◽  
Sustainable Regional Development ◽  
Three Factor

A systematic analysis of the concept of "sustainable development of the region" is carried out . The classification of factors that affect the process of sustainable development is given. A three -factor resource model for the formation of sustainable development of the region , including human, financial and raw materials, is described. The necessity of systematic monitoring as an element of regional development control is substantiated.

Organic chemical devulcanization of rubber vulcanizates in supercritical carbon dioxide and associated less eco-unfriendly approaches: A review

2021 ◽  
pp. 0734242X2110085
Author(s):  
Jabulani I Gumede ◽  
Buyiswa G Hlangothi ◽  
Chris D Woolard ◽  
Shanganyane P Hlangothi
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Negative Impact ◽  
Raw Materials ◽  
Chemical Components ◽  
Organic Chemical ◽  
Attractive Alternative ◽  
Special Focus ◽  
Waste Tyres ◽  
Supercritical Carbon

There is a growing need to recover raw materials from waste due to increasing environmental concerns and the widely adopted transition to circular economy. For waste tyres, it is necessary to continuously develop methods and processes that can devulcanize rubber vulcanizates into rubber products with qualities and properties that can closely match those of the virgin rubber. Currently, the most common, due to its efficiency and perceived eco-friendliness in recovering raw rubber from waste rubbers, such as tyres, is devulcanization in supercritical carbon dioxide (scCO2) using commercial and typical devulcanizing agents. The scCO2 has been generally accepted as an attractive alternative to the traditional liquid-based devulcanization media because of the resultant devulcanized rubber has relatively better quality than other processes. For instance, when scCO2 is employed to recover rubber from waste tyres (e.g. truck tyres) and the recovered rubber is blended with virgin natural rubber (NR) in various compositions, the curing and mechanical properties of the blends closely match those of virgin NR. The atmospheric toxicity and cost of the commonly used devulcanization materials like chemical agents, oils and solvents have enabled a shift towards utilization of greener (mainly organic) and readily available devulcanization chemical components. This literature review paper discusses the approaches, which have less negative impact on the environment, in chemical devulcanization of rubber vulcanizates. A special focus has been on thermo-chemical devulcanization of waste tyres in scCO2 using common organic devulcanizing agents.

scholarly journals Electrochemical multicomponent synthesis of 4-selanylpyrazoles under catalyst- and chemical-oxidant-free conditions

2021 ◽  
Author(s):  
Yan Wu ◽  
Jin-Yang Chen ◽  
Jing Ning ◽  
Xue Jiang ◽  
Jie Deng ◽  
...  
Keyword(s):  
Multicomponent Reaction ◽  
Raw Materials ◽  
Multicomponent Synthesis ◽  
Mild Conditions ◽  
Simple Protocol ◽  
High Yields

An electrochemical multicomponent reaction was established under catalyst-, chemical-oxidant-free and mild conditions, which provides an eco-friendly and simple protocol for constructing 4-selanylpyrazoles from easily available raw materials with high yields.

scholarly journals Nitrile Synthesis with Aldoxime Dehydratases: A Biocatalytic Platform with Applications in Asymmetric Synthesis, Bulk Chemicals, and Biorefineries

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4466
Author(s):  
Pablo Domínguez de María
Keyword(s):  
Asymmetric Synthesis ◽  
Organic Solvents ◽  
Raw Materials ◽  
Aqueous Media ◽  
Industrial Processes ◽  
Polymer Chemistry ◽  
Fine Chemicals ◽  
Mild Conditions ◽  
Bulk Chemicals ◽  
Recent Developments

Nitriles comprise a broad group of chemicals that are currently being industrially produced and used in fine chemicals and pharmaceuticals, as well as in bulk applications, polymer chemistry, solvents, etc. Aldoxime dehydratases catalyze the cyanide-free synthesis of nitriles starting from aldoximes under mild conditions, holding potential to become sustainable alternatives for industrial processes. Different aldoxime dehydratases accept a broad range of aldoximes with impressive high substrate loadings of up to >1 Kg L−1 and can efficiently catalyze the reaction in aqueous media as well as in non-aqueous systems, such as organic solvents and solvent-free (neat substrates). This paper provides an overview of the recent developments in this field with emphasis on strategies that may be of relevance for industry and sustainability. When possible, potential links to biorefineries and to the use of biogenic raw materials are discussed.

Sign in / Sign up

Export Citation Format

Share Document