Chitosan is a product obtained from chitin, which has been found in a wide range of natural resources including crustaceans [12, 21, 22] and fungi [11, 18, 23]. The production of chitosan from chitin can be performed by distinct methods[24], but the most common is the process called deacetylation[11, 23] which consists in the removal of the acetyl group and is usually performed with concentrated NaOH at high temperatures[16, 25].
The characteristics of chitosan that may affect its sorption properties should be explain in order to understand the values and limitations of the chitosan used in this experiment. These include the degree of deacetylation, the structural condition and the crystallinity.
The degree of deacetylation has to be greater
…show more content…
Chemistry text books explain that because of its small size, copper ions attract ligands, which are species that are rich in electrons and can form co-ordinate covalent bonds (can donate electrons) to form complex ions[28].
When the copper ion is joined to one or more ligands, a coordination complex is formed where the ligands act as electron donors, and the central atom of copper acts as an electron-pair acceptor. This complex has a structure called coordination sphere[2], with four ligands attached to the central atom.
Adsorption is a process where one or more components (adsorbates) are attracted and bonded to the surface of a solid (adsorbent) with which they are in contact[29]. Chitosan is effective in the adsorption of metal ions due to its vast number of amine groups (-NH2) [12, 14, 15], which are the main active sites[11, 12, 14, 18, 21, 30] and the hydroxyl (-OH) groups, which contribute to a lesser extent[11, 14, 18, 21, 30]. Possible adsorption mechanisms of metal ion uptake by chitosan include the formation of ternary complexes, electrostatic repulsion and chelation [14, 31]. The formation of ternary complexes is the mechanism for the adsorption of alkaline and alkaline-earth ions[29], and the electrostatic repulsion occurs in systems concerning chitosan and anions[29], therefore those mechanism
…show more content…
This model is less preferred by scholars, who do not usually find evidence of its existence such as data from colorimeters or IV spectrometers. While there is no general consensus for the chelation of copper by chitosan in the actuality, the balance seems to be titled in favour of the pendant model. However, scholars suggest that chelation is extremely dependant on factors such as contact time, temperature, pH and adsorbent dose [36, 37], therefore it is conceivable that this type of chelation occurs in some specific conditions, but probably not as commonly as the pendant
The purpose of this lab was to to cycle solid copper through a series of chemical forms and return it to its original form. A specific quantity of copper undergo many types of reactions and went through its whole cycle, then returned to its solid copper to be weighted. We observed 5 chemical reactions involving copper which are: Redox reaction (which includes all chemical reactions in which atoms have their oxidation state changed), double displacement reaction, precipitation reaction, decomposition reaction, and single displacement reaction.
Since the discovery of cisplatin, thousands of platinum complexes were evaluated, but only five were approved. Consequently, more than 10000 compound need to be screened so as to get a novel and more effective anticancer drug than cisplatin with the aid of inorganic or coordination chemistry. Solubility, reactivity, electronic and steric effects, and the configuration of metal complexes can be controlled by modifying the metal to other transition metal such as Pd and Ni or the ligand around the metal atom which has been reported that both the metal and the ligand can determine the biological activity. Hopefully we can find more efficient drugs that may contain much less side effects than cisplatin, as well as solve the problem of overcoming drug resistance of some cancers to cisplatin.
Society of Environmental Toxicology and Chemistry. (2013). SETAC/Rachel Carson Award - Society of environmental toxicology and chemistry. Retrieved from Society of Environmental Toxicology and Chemistry: http://www.setac.org/?SETACAwardSRachel
Regardless of chitosan's miraculous overview, it is a very simple substance which has been around for ages. It is taken from chitin, a polysaccharide found in the exoskeletons of crustaceans. It is processed by removing the shells from shellfish such as shrimp, lobster, and crabs. The shells are then ground into a pulverous powder. This powder is then deacetylated, or basically stripped of specific chemical groups which allows the compound to thus actively "soak up fats." Or so this is what the producers claim. It has been used in the past in the process of detoxifying water. It was simply spread over the surface of water, where it would immediately absorb any toxic substances such as greases, oils, or dangerous heavy metals. The process is so complete that a scum forms over the surface of water and is then easily removed. For this reason, chitosan is extremely popular all over the world in water purification plants. The present form of chitosan has just been introduced recently as a
Cellulose chains are composed of both crystalline and amorphous regions. Breaking of the amorphous portion of cellulose chain is carried out by acid hydrolysis to yield crystalline residue that is CNCs. Hydrolysis largely disintegrates the acetal linkage in amorphous part of cellulose chain while due to long exposure to acid crystalline part may also degrade (Bondeson et al., 2006). Depending on the origin of the cellulose, CNCs of different width and length have been prepared and reported by different researchers. The aspect ratio (length to width ratio) of CNCs have been observed to vary between 10 and 30 for cotton and it lies around 70 for tunicate, a sea animal (Habibi et al., 2010). CNCs of various shapes viz. rod like (Habibi et al., 2010), spherical (Wang et al., 2008) and elliptical (Lu et al., 2012) have been obtained using different acid system and different cellulose origin. Sulphuric acid is the most commonly used acid for hydrolysis of cellulose to synthesize CNCs (Kim et al., 2001; Kupiainen et al., 2012; Lalia et al., 2013; Lu et al., 2012). The presence of bisulphite ion along with H+ ions results in better cellulose hydrolysis in sulphuric acid as compared to non-sulphur acid species like formic acid (Kupiainen et al., 2012). Hydrolysis using sulphuric acid leads to the introduction of charged sulphate ester groups to the surface CNC s (Abitbol et al., 2013; Lu & Hsieh, 2010). These sulphate groups attached to the CNC surfaces results in decreasing the thermal degradation temperature of CNCs (Jiang et al., 2010). To improve the thermal stability of CNCs, hydrochloric acid has been used as hydrolysing agent for hydrolysis of cellulose (Yu et al.,
This happens at the cathode: Cu2+ +2e- = Cu And oxygen is produced at the anode. Increasing the concentration is more affective than increasing the voltage but in order to gain more copper, you will need the highest
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
== § Test tubes X 11 § 0.10 molar dm -3 Copper (II) Sulphate solution § distilled water § egg albumen from 3 eggs. § Syringe X 12 § colorimeter § tripod § 100ml beaker § Bunsen burner § test tube holder § safety glasses § gloves § test tube pen § test tube method = == = =
== == I completed a table to show my results, here is the table: Table 1. Results of different changes of substances Part A Copper (II) Sulfate and Water Reactant description Water (reactant): Color: Colorless Transparency:
It forms from the outer skeleton of insects and crusta-ceans like lobster, crabs, and shrimp [26]. In chitin, the compound structure which is like cel-lulose, every monomer having one hydroxyl grouping which is substituted with an acetyl amine gathering (Figure 2). The extraction of chitin followed by a deproteinization (removal of proteins) which involves the removal of an acid calcium carbonate (demineralization), done mostly through the hot reaction with HCl, HNO3 etc., This step generally achieved by alkaline treatments (e.g. With NaOH) [27]. Chitin has an extremely well-arranged crystalline structure in its extracted crude form which is shining, strong and quite tough. But it has low reactivity and poor
(Khan): further states, here L are the Ligand and which is formed via the complete replacement of water molecules by other ligands can occur till the formation of the MLn complex. “n” is the coordination number of the metal ion and represents the maximum number of monodentate ligands which can be bound to it [8]
Secondly, the ionic bond involves transfer the electrons to achieve a completely filled outer shell. This type of bond occurs between metals and nonmetals. When the metals want to lose their electron, the nonmetals want to gain to achieve noble gas configuration. The crystals which have this type of bond, have hardness and specific gravity moderately. They have also high melting point and they are poor conductors. Bonding in most of the minerals is largely ionic.
When ligands are bonded to a transitional metal when forming a coordination compound a split of the d-orbital occurs. It is split into high and low energy orbitals, this energy difference is referred to as∆ and this delta is a property of both the ligand and the metal.
V. Amarnath, D. C. Anthony, K. Amarnath, W. M. Valentine, L. A. Wetterau, D. G. J. Org. Chem. 1991, 56, p. 6924-6931.
If the distance between the two electrodes is smaller, the copper ions need less energy to flow from the anode to the cathode