Crab shell

Two hundred grams of eleaned and dried crab shells (Note 1) ground to a fine powder is placed in a 2-1. beaker, and an excess of dilute (approximately 6 N) commercial hydrochloric acid is added slowly to the powdered material until no further action is evident. Much frothing occurs during the addition of the acid, and care must be exercised to avoid loss of material due to foaming over the sides of the beaker. After the reaction has subsided, the reaction mixture is allowed to stand from 4 to 6 hours to ensure complete removal of calcium carbonate. The residue is then filtered, washed with water until neutral to litmus, and dried in an oven at 50-60°. The weight of dried chitin is usually about 70 g., but with some lots of crab shells it may be as low as 40 g. 

The cleaned and dried crab shells were obtained from Carter and Lanhardt Company, Eleventh and Main Avenue, S.W., Washington, D. C. 

The preparation of glucosamine hydrochloride from lobster shells and crab shells by essentially this method has been reported by Irvine, McNicoll, and Hynd and Hudson and Dale. Other methods involving the use of cicad larvae shells and shrimp shells ls also have been reported. 

Recent development of mbber nanocomposites by other nanofillers includes piezo-mbber application by incorporating lead-zirconate by Tandon et al. [69], Fe-containing silicone mbber by Yurkov et al. [70], and crab shell whisker-reinforced natural mbber nanocomposites by Nair and Durfreshe [71]. 

Methods and technology were developed to analyze 1000 samples/yr of coal and other pollution-related samples. The complete trace element analysis of 20-24 samples/wk averaged 3-3.5 man-hours/sample. The computerized data reduction scheme could identify and report data on as many as 56 elements. In addition to coal, samples of fly ash, bottom ash, crude oil, fuel oil, residual oil, gasoline, jet fuel, kerosene, filtered air particulates, ore, stack scrubber water, clam tissue, crab shells, river sediment and water, and corn were analyzed. Precision of the method was 25% based on all elements reported in coal and other sample matrices. Overall accuracy was estimated at 50%. 

Deacetylated chitin can be prepd by the method of Rigby(Ref 3) which consists of heating at 110° for 4hrs, shrimp, lobster or crab shells(previoulsy washed by successive treatments with boiling 1% NaOH soln, 5%... 

The hard outer skeleton of insects and shellfish contains chitin, a polymer very like cellulose but made of acetyl glucosamine instead of glucose itself. It coils up in a similar way and provides the toughness of crab shells and beetle cases. 

Most of the things you can see about you at this moment are made of organic polymers. Skin, clothes, paper, hair, wood, plastic, and paint are among them. Teeth, muscle, glue, cling film, starch, crab shells, and marmalade are all polymer-based too. In this chapter we will explore the world of polymers. We will ask questions like these ... 

D., University of Delaware, unpublished data). Since these experiments were carried out with chitosan obtained from crab shells, further experiments with chitosan isolated from Mucor rouxii (47) will prove whether microbially produced chitosans are more effective elicitors for the biosynthesis of certain phytochemicals than those obtained from marine organisms. 

Chitosan Natural (crab shells) Deacetylation of chitin Soluble in aqueous solutions (low pH), insoluble in organic solvents... 

In the United States, a cleaned crab shell is commercially available from enterprises employing ants for this purpose, such cleaned shells then being utilized as dishes in a tjrpe of shore-dinner popular on the Atlantic seaboard. 

An, H.K., Park, B.Y., and Kim, D.S. 2001. Crab shell for the removal of heavy metals from aqueous solutions. Water Research, 35 3551-6. 

Niu, H. and Volesky, B. 2003. Characteristics of anionic metal species biosorption with waste crab shells. Hydrometallurgy, 71 209-15. 

FIGURE 2.10 XRPD patterns for (A) a-chitin from different sources (1) brown shrimp shells, (2) pink shrimp shells, (3) crabs shells, and (4) crayfish shells (B) the corresponding chitosan. 

In the area of renewable materials, bulk oxypropylation of chitin and chitosan has been performed. Chitin and chitosan are abundant natural polymers obtained from shellfish, such as crab shell or shrimp shell. This solvent free reaction yields viscous polyols. Unfortunately, propylene oxide homopolymer is formed as a by-product but is easily separated. It should be noted that care was taken to minimize the risk involved in the use of toxic, flammable propylene oxide (the reagent in this process). 

Glucosamine, an over-the-counter remedy used for osteoarthritis, and chitin, the carbohydrate that gives rigidity to crab shells (Section 27.14A)... 

The rigidity of a crab shell is due to chitin, a high molecular weight carbohydrate molecule. Chitin-based coatings have found several commercial applications, such as extending the shelf life of fruits. Processing plants now convert the shells of crabs, lobsters, and shrimp to chitin and various derivatives for use in many consumer products. 

Coughlin, R.W., Deshaies, M.R., and Davis E.M., Chitosan in crab shell wastes purifies electroplating wastewater. Environ. Prog., 9, 35, 1990. 

Chitin A natural polysaccharide obtained from crab shells The chain is based on acetylated glucosamine units the natural polymer can be converted to the acid-soluble partially deacetylated product chitosan... 

Chitosan is a natural glucosamine polymer obtained from crab shells. The polymer retains Cu(II) more strongly than does cellulose. It was used in LEC of amino acids, peptides, and enzymes. 

---