Preparation and Property of Chitosan Containing Adsorbents:Heavy Metal Removal

• Main Authors: Chang, Yu-Hsin, 張煜欣
• Other Authors: Chang, Feng-Chih
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/92289346825245453175

博士 === 國立交通大學 === 應用化學系所 === 97 === Heavy metals, such as copper and mercury, may be regarded as toxic. Although copper is an essential element for human, large and acute doses can be harmful, even fatal, effects. Mercury is not biodegradable and tends to accumulate in living organisms, causing various diseases and disorders. In recent years, widespread concern over these issues has lead to extensive research in developing effective alternative technologies for the removal of these potentially damaging substances from solutions. One promising technique for accumulating metals is using biopolymers as adsorbents, which can reduce heavy metal concentrations to environmentally acceptable levels at affordable costs. Chitosan is a natural cationic biopolymer formed by the N-deacetylation of chitin, which is present in fungi, insects, and crustaceans. Besides its versatile properties and numerous applications, chitosan has been shown to effectively remove several metals from aqueous solutions. Chitosan is a very promising material as adsorbent when compared with other conventional ones because of its advantages such as biodegradability, hydrophilicity, presence of functional groups, and natural origin. The objective of this study is to investigate the application of chitosan containing material for the heavy metal removal from solutions, and its metal adsorption behavior. The experimental work in this dissertation was divided into three chapters: (1) The partially deacetylated crab shell (chitosan) was successfully prepared to meet the requirement of both feasibility and cost. By carrying out the batch type adsorption experiments and the breakthrough experiments, we compare the Cu2+ adsorption of partially deacetylated chitosan and a commercial chelating resin. We also compare the conductivity removal of these two adsorbents by using the batch type adsorption experiments. (2) Alginate gel containing chitosan (abbreviated as AGCC) was prepared by immobilizing glutaraldehyde-crosslinked chitosan into calcium alginate gel bead via entrapment, and used for the removal of Hg2+ ions from aqueous solutions. Both high uptake capacity (667 mg / g) and fast time (60 min) to equilibrium were demonstrated as the excellent characteristics of AGCC. (3) A composite carbon adsorbent, alginate gel containing chitosan and activated carbon (abbreviated as GCA), was successfully prepared. The combination of these two materials, activated carbon and chitosan, resulted in high adsorption capacity (576 mg / g) and fast time (70 min) to reach adsorption equilibrium for Hg2+. GCA could be applied to a great variety of water treatment (e.g. drinking water) due to the contained activated carbon.