Bioethics in India: Proceedings of the International Bioethics Workshop in Madras: Biomanagement of Biogeoresources, 16-19 Jan. 1997, University of Madras; Editors: Jayapaul Azariah, Hilda Azariah, & Darryl R.J. Macer, Copyright Eubios Ethics Institute 1997.
http://eubios.info/index.html

39. Behind all that glitters

S. Vatsala
Department of Chemistry, Providence Women's College, Calicut 673 009


The yellow metal gold has lured humankind from time immemorial. People have always been fascinated by its glitter. The period of alchemy, has contributed to the early insight into chemistry. People in their attempt, to convert base metal into gold, have done a lot of worthwhile experiments. Despite all the hard work, the attempt, understandably, was not successful. Groping in the dark and tempted by greed and undeterred by failures, the alchemists continued to struggle, to find a formula for the conversion of base metal into gold and this led to the early knowledge of chemistry of other elements.

India tops the countries in the demand and consumption of gold. For an average Indian household, no auspicious event is complete without gold ornaments, finding an important place. Besides gold being used for ornamental purposes, it is a dependable and ready source of finance available to its holders.

The ornaments sold by a jeweler is understood to be of 22 karat fineness. Invariably the consumer has to pay the cost of 22 karat while purchasing, though its fineness is never tested or questioned and no scientific method is employed to determine the fineness of the gold. Trade is carried on, on faith, though the purchaser is the loser, if it is otherwise. The same is the case when old ornaments are sold. The jeweler , in order to determine the fineness, resorts to the only conventional method of rubbing the gold on a touchstone. His assessment though arbitrary is final and thrust upon the seller, which is always and every time advantageous to the purchaser (the jeweler). The gold of the ornaments so collected cannot be naturally uniform in fineness. To obtain the required fineness, the jeweler subjects the ornaments to an elaborate acid process.

Acid process

The old ornaments are melted, adding twice its weight of silver, in a graphite crucible. The molten alloy is poured into a vessel containing cold water, when thin flakes are formed. These flakes are collected and heated with plenty of concentrated HNO3 in a big stainless steel vessel. Copper (present in the melted ornaments) and silver dissolve forming the respective nitrates, leaving undissolved gold in the form of fine, brown coloured powder.

Cu + 4HNO3 Cu(NO3)2 + 2H2O + 2NO2

Ag + 2HNO3 AgNO3 + H2O + NO2

The supernatant liquid* (blue coloured due to Cu(NO3)2) is decanted. The brown powder which looks like mud is collected and melted in a graphite crucible when glittering pure yellow metal is obtained. During this process, huge volumes of nitrogen dioxide (NO2) escape into the atmosphere, NO2 is an acidic oxide which is known to cause acid rain, photochemical smog; and asthma and other respiratory disorders.

On inhalation, NO2 combining with oxygen and moisture forms globules of HNO3 in lungs, as could be seen from the following equation.

4NO2 + O2 + 2H2O 4 HNO3

Lung comprising thin membranous tissue would be greatly affected by the acid thus formed.

Suggested remedy

NO2 being acidic in nature can get easily absorbed in slaked lime[Ca(OH)2], forming Ca(NO3)2, which is a good fertilizer.

2Ca(OH)2 + 4NO2 + O2 2Ca(NO3)2 + 2H2O

For this purpose a suitable vessel packed with the absorbent, Ca(OH)2 and coconut fiber,

in alternate layers has been designed, and found to be effective in absorbing NO2.

The supernatant liquid*, decanted in the previous process contains silver in the form of AgNO3. To recover silver, the above solution is diluted 15 - 20 times with water. Into the diluted solution thick copper rods are immersed. Due to displacement reaction, silver gets deposited on the copper rod in the form of powder.

2AgNO3 + Cu Cu(NO3)2 + 2Ag.

After recovering silver the remaining solution contains plenty of nitric acid and copper in the form of Cu(NO3)2. This solution is discarded without any treatment. As a consequence, there is the risk of soil and the nearby water bodies being contaminated with HNO3 and Cu(NO3)2. In acidic soil, microbial population can get reduced/altered. Earthworms are not capable of surviving below pH 4.5. Therefore the soil may become unfit for cultivation.

1) The decanted liquid can be subjected to distillation and HNO3 can be collected and recycled.

2) The residual content of the distillation flask can be diluted with water. To this solution, calculated quantity(depending upon the quantity of the silver to be recovered) of Na2CO3 can be added, when Ag2CO3 (yellow precipitate) gets precipitated. The precipitate is allowed to settle and collected by decanting the supernatant**

2AgCO3 4Ag + 2CO2 + O2

The above** supernatant solution is further treated with Na2CO3 when copper precipitates as CuCO3.

Cu(NO3)2 + Na2CO3 CuCO3 + 2NaNO3

(green precipitate)

From the precipitated CuCO3, copper can be recovered and recycled. The remaining solution can be allowed to evaporate using solar energy(the cheapest available energy) and NaNO3 can be recovered which is yet another useful fertilizer.

Polishing Ornaments

The polishing of the ornaments is done by electrolysis. Potassium cyanide or sodium cyanide is used in the electrolytic bath, along with some plant resins, sealing wax. The contents of the electrolytic bath, after repeated use is discarded- again without any treatment to nullify the toxic effect of cyanide.

To summarize, since only traditional artisans are working in this field, proper education regarding the chemicals they use, and the formidable consequences of the process is the first and foremost need. Jewelry production does not seem to be considered as an industry and hence there is no restraint on the quantity or the variety of toxic chemicals used in the purification, soldering and polishing processes. No pollution control measures are employed, nay not even be contemplated, and they are at present happily indulging in the process with impunity. If scientific methods are introduced for proper management of the effluents/process, a welcome step in the direction of pollution control would have been taken. The people engaged in the process are in blissful ignorance of the alarming situation and therefore the situation cries for immediate scientific intervention.


40. Iodized salt: Myth and Reality
Iodine is an important nutrient, the deficiency of which causes iodine deficiency diseases (IDD). To prevent the occurrence of IDD, Govt. of India had given an order to completely replace common salt with iodized salt by the year 1992 (1). This is to say, the sale of non iodized salt, for human consumptions is banned by the Government of India.

What is iodized salt?

Common salt (which is mainly sodium chloride) is obtained by evaporating sea water in salt pans, using solar energy. For this reason, it is called solar salt. On further purification, the sample obtained is devoid of the contaminants which are the salts of calcium and magnesium. The removal of these salts makes the salt dry and is free flowing in nature. To this dry sample of sodium chloride, potassium iodide or potassium iodate is added up to a concentration of 20ppm. Hence the iodized salt is sodium chloride from which calcium and magnesium salts have been removed by purification and to which KI or KIO3 is added.

The chemistry of iodine and iodide

Iodine is one of the members of halogen family. It is the most beautiful of all the elements (2). It is a black shining crystalline substance. It's solution either in water or any other organic solvent is brown in colour. It's vapours are violet in colour. Iodine is subliminal in nature. Of all the halides the size of iodide ion is the biggest. For this reason iodides are most soluble in water. It is a very strong reducing agent. It easily gets converted to iodine, when exposed atmospheric oxygen, especially in acid medium (3).

2 I I2 + 2e

(Iodide is represented as I and Iodine as I2 and e in the above equation is electron)

The importance of calcium and magnesium

These two metal ions are very essential nutrients. They have vital roles to play in body functions. Magnesium is required for a number of enzymatic reactions, connected with energy transactions in the body. Magnesium is a cofactor of many enzymes and is contained in metalloenzymes (4). The construction of biomolecules requires energy in the form of ATP and whenever there is ATP, there is an obligatory need for magnesium (5). Magnesium ions inhibit the growth of calcium oxalate crystal in vitro and there are reports that renal stone development in vivo is inhibited by prolonged administration of MgO (6). Evidences have been reviewed recently, suggesting and inverse relationship of magnesium in drinking water to cerebrovascular and cardiovascular diseases (7). An inverse relationship between the incidence of strokes and the hardness of drinking water has been reported (8). Calcium is essential to maintain healthy bones and teeth. It is required to trigger the contraction of the muscles to maintain the regular beating of heart (9). Calcium is essential for neurotransmitter release, as well as for the release of hormones (10).

It was the year 1900, an American doctor David Marine suggested that iodine (in the form of iodide) be added to drinking water and TABLE SALT (11). Small amounts of iodine are required in our diet. So, traces of sodium iodide are added to TABLE SALT (12). The new Encyclopedia Britannia (13), defines iodized salt as TABLE SALT with small amounts of iodine added, usually as potassium iodide to guard against the dietary deficiency of iodine. The new book of knowledge says salt sold for table use often has iodine added to it to prevent disease called goiter (14). The word TABLE SALT has to be taken note of, in all the above cases. Table salt is, what is used on dining table without being subjected to cooking. In our Indian context the word table salt has become synonymous with powder salt. Further we don't differentiate table salt from cooking salt.

Consequences

The two unintended disadvantages to iodized salt are: (i) Calcium and magnesium get eliminated while the common salt is purified; (ii) The iodide that is added to the salt escapes as iodine while cooking/storing. As a result the very purpose of switching on to iodized salt is totally defeated and the loss in nutritional value is manifold.

An alternative

The remarkable successful method is the injection of iodized oil, from which iodine is slowly released, the effect of a single injection lasting 3 to 5 years. Pioneered in New Guinea, this method has now being applied with striking benefit, in other parts of the world (15).

The following remedial actions are suggested:

1. The ban on the sale of unionized salt should be lifted with immediate effect in all the states of the country.

2. The use of common salt (solar salt) should be encouraged deployed on a large scale at state level.

3. Other means of supplementing iodine, such as iodized oil should be thought of and

4. The nation wide myth of iodized salt being beneficial is to be exploded, with appropriate education at all levels.

References
1. Jan, Nutrition, National Institute of Nutrition, Hyderabad (1989).
2. Discovery of elements, Paico Publishing House, Cochin (1967).
3. Therald Moeller, Inorganic Chemistry An Advance Text Book, Asia Publishing House 5th edition, (1956).
4. F.W. Oehme, ed., Toxicity of Heavy Metals in the Environment, part -2, Marcel Dekkar, Inc. New York and Basel, (1979).
5. J. K. Aikawa Magnesium; Its Biologic significance CRC press, Inc. (1981).
6. D. J Weatherall, J.G.G. Ledingham, D.A. Warrel, ed., Oxford Text Book of Medicing, Vol -2, Page 18. 92, ELBS, Oxford University Press. (1988)
7. Takahashi . E, Geographic Distribution of Mortality rates from cerebrovascular diseases in European countries, Tohoku, J. Exp. Med, 92, 345, (1967).
8. Kobayashi. J., On Geographical Relationship Between the Chemical Nature of River Water and Death rates from apoplexy. Ber, Ohara Inst. Landwirtsch, Biol.Okayama Univ., 11,12., (1957).
9. J.D. Lee, Concise Inorganic Chemistry, p-353; IV.
10. As in Ref (6) - p-10.51.
11. Molecules to Man, published by American Institute of Biological Sciences P-536., (1963).
12. As in Ref -(9)- p-590.
13. The New Encyclopedia Britanica, 15th Edit. Vol-6.
14. The New Book of Knowledge, Grolier Incroporated, Dangber, Connecticut, Vol - 17, p-21.
15. As in Ref (6) - P-10-36.


Please send comments to Email < Macer@biol.tsukuba.ac.jp >.

To Bioethics in India book contents
To Eubios Ethics Institute books
To Eubios Ethics Institute home page