Kelps

This reaction is also used on a large scale, to obtain iodine from seaweed. The ash from burnt seaweed ( kelp ) is extracted with water, concentrated, and the salts other than iodides (sulphates and chlorides) crystallise out. The more soluble iodides remain and the liquor is mixed with sulphuric acid and manganese dioxide added the evolved iodine distils off and is condensed. 

The chemical characteristics of biomass vary over a broad range because of the many different types of species. Table 8 compares the typical analyses and energy contents of land- and water-based biomass, ie, wood, grass, kelp, and water hyacinth, and waste biomass, ie, manure, urban refuse, and primary sewage sludge, with those of cellulose, peat, and bituminous coal. Pure cellulose, a representative primary photosynthetic product, has a carbon content of... 

Analysis Pure ceUulos e Pine wood Kentuck y bluegrass Giant brown kelp Feedlo t manur e Urban refuse Primary sewage sludge Reed sedge peat Illinois bituminous coal... 

Typical methane yields and volatile soHds reductions observed under standard high rate conditions are shown in Table 12. Longer detention times will increase the values of these parameters, eg, a methane yield of 0.284 m at normal conditions /kg VS added (4.79 SCF /lb VS added) and volatile soHds reduction of 53.9% for giant brown kelp at a detention time of 18 days instead of the corresponding values of 0.229 and 43.7 at 12 days under standard high rate conditions. However, improvements might be desirable in the reverse direction, ie, at shorter detention times. 

Daily feeding, continuous mixing, 35°C, pH 6.7 to 7.2, 12-day hydrauHc retention time, 1.6 kg volatile solids/m d except for kelp, which was 2.2 kg VS/m -d. All biomass substrates 1.2 mm or less ia size. 

Still another possibiUty is a marine biomass plantation such as that envisaged for giant brown kelp grown off the California coast and conversion of the kelp to methane in a system similar to that shown in Figure 19. The location of the SNG plant could be either on a floating platform near the kelp growth area or located on shore, in which case the biomass or fuel transport requirements would be different. 

W. J. North, ed.. The Biology of Giant Kelp Beds (Macroystis) in California, Cramer, Lehre, Germany, 1971, p. 12. 

Seaweeds. The eadiest successful manufacture of iodine started in 1817 using certain varieties of seaweeds. The seaweed was dried, burned, and the ash lixiviated to obtain iodine and potassium and sodium salts. The first process used was known as the kelp, or native, process. The name kelp, initially apphed to the ash of the seaweed, has been extended to include the seaweed itself. About 20 t of fresh seaweed was used to produce 5 t of air-dried product containing a mean of 0.38 wt % iodine in the form of iodides of alkah metals. The ash obtained after burning the dried seaweed contains about 1.5 wt % iodine. Chemical separation of the iodine was performed by lixiviation of the burned kelp, followed by soHd-Hquid separation and water evaporation. After separating sodium and potassium chloride, and sodium carbonate, the mother Hquor containing iodine as iodide was treated with sulfuric acid and manganese dioxide to oxidize the iodide to free iodine, which was sublimed and condensed in earthenware pipes (57). 

Iodine. Of the 10—20 mg of iodine in the adult body, 70—80 wt % is in the thyroid gland (see Thyroid and antithyroid preparations). The essentiahty of iodine, present in all tissues, depends solely on utilisation by the thyroid gland to produce thyroxine [51-48-9] and related compounds. Well-known consequences of faulty thyroid function are hypothyroidism, hyperthyroidism, and goiter. Dietary iodine is obtained from eating seafoods and kelp and from using iodized salt. 

Tang, m. seaweed, -asche, /. seaweed ashes, kelp. 

Tang-sa ire, /. tangic acid, tang acid, -soda, /. kelp. 

Some naturally occurring organohalogen compounds are produced in massive quantities. Forest fires, volcanoes, and marine kelp release up to 5 million tons of CH3CI per year, for example, while annual industrial emissions... 

Alginates are made up of long chains of two monomers guluronic acid and mannuronic acid. The chains can be made of all one monomer or mixtures of both. The stems of kelp are made of chains with more guluronic acid, and the leaves (fronds) have more mannuronic acid. Guluronic chains bind tightly to calcium in mannuronic chains the calcium is more easily replaced by sodium, allowing the fibers to swell easily. 

Estes, J. A. and Steinberg, P. D. 1988. Predation, herbivory and kelp evolution. Paleobiol. 14 19-36. Evans, 1. A. 1976. Relationship between bracken and cancer. Pages 105-112 in F. H. Perring and B. G. Gardiner (eds.). The biology of bracken. Linnean Society of London-Academic Press, London. 

Steinberg, P. D. 1984. Algal chemical defense against herbivores allocation of phenolic compounds in the kelp Alaria marginata. Science 223 405 07. 

KEY T J A, THOROGOOD M, KEENAN J, LONG A (1992) Raised thyroid stimulating hormone associated with kelp intake in British vegan men. J Hum Nutr Diet. 5 323-6. 

In western and northwestern England, Ireland, Scotland, and Norway and in the Hebrides and Orkney Islands, peasants neglected their farms and herds three months of the year to cut seaweed and haul it ashore. Instead of using it to manure their fields or overwinter their cattle, they dried and burned the seaweed, boiled the ashes, evaporated the liquid, and earned pennies for their pains. The result, called kelp, was only 5 to 8 percent sodium and potassium carbonate. Kelp made big landowners wealthy, but it impoverished peasant farmers. 

But not all the potash, kelp, and barilla in Europe and North America could keep up with the cotton textile factories of Britain and France. France was in a particularly dire situation. Even under normal conditions, her natural sources of alkali were insufficient. Then France supported the American War of Independence, and British ships cut off the French supply of American potash. With gunpowder and textile industries dependent on potash, France had to find a way to make artificial alkali. 

Leblanc s process survived him. Within several decades, it was almost the only one used to produce washing soda for the textile, soap, glass, and papermaking industries. And eventually his synthetic sodium carbonate put the barilla and kelp collectors out of business. 

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