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Biosorption of lead ,cadmium,and mercury ions on loofa sponge immobilized biomass of Aspergillus terreus. 指導老師 : 孫 逸 民 教授 學 生 : 田 汶 玄. Introduction(1).
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Biosorption of lead ,cadmium,and mercury ions on loofa sponge immobilized biomass of Aspergillus terreus 指導老師: 孫 逸 民 教授 學 生: 田 汶 玄
Introduction(1) Heavy metals are discharged from various industries such as electroplating, metal finishing, textile, storage batteries, mining, ceramic and glass.
Introduction(2) The commonly used procedures for removing metal ions from wastewater include chemical precipitation, ion exchange, membrane separation, reverse osmosis, and electrolysis.
Introduction(3) However, these techniques have certain disadvantages such as incomplete removal, high reagent and energy requirements, generation of toxic sludge.
Introduction(4) The search for alternative treatment techniques has focused attention on the use of biological materials such as algae, fungi, yeast and bacteria for the removal and recovery technologies and because of the better performance and low cost of these biological materials .
Introduction(5) The purpose of the present study is to provide an immobilized biosorption system using a low cost, physically strong, and highly porous immobilization matrix; loofa sponge.
Introduction(6) The study investigated the use of loofa sponge immobilized fungal biomass as a biosorbent for the removal of lead, cadmium ,and mercury from aqueous solution.
Microorganism The Aspergillus terreus was maintained by pure culturing on potato dextrose agar slants at 28 ℃ for 7 days. Mycelium suspensions from 7-day old cultures, preculture on glucose at 28 ℃ for 24 hours. Then, above Mycelium suspensions was main culture for 15 days.
Pretreatment of loofa sponge The fibrous sponge was cut into discs of approximately 0.2g , soaked in boiling water for 30 min, thoroughly washed under tap water, and left for 24 h in distilled water, changed 3-4 times. The sponge piece were oven dried at 70 ℃.
Immobilization of A.terrues within loofa sponge The mycelium suspension (2.5 ml) was inoculated into 250 ml flasks containing 50 ml of the growth medium and pre-weighed loofa sponge discs. The inoculated flasks were incubated at 28 ℃ and shaken at 200 rpm. After 15 days of incubation, loofa sponge immobilized A.terrues were harvested from the medium, washed twice with distilled water and stored at 70 ℃ until use.
Biomass of fungal growth The dry weight of the fungal biomass entrapped within sponge pieces was determined by weighing sponge pieces before and after fungal growth after 48 h drying at 70 ℃.
Metal solutions HgCl2 (Riedel-de Haën) CdCl2‧2.5H2O (Panreac ) PbCl2 (J. T. Baker)
Biosorption studies The biosorption capacity of FBILS (fungal biomass immobilized in loofa sponge) was determined by contacting 100 ml metal solution of known concentration in 250 ml flasks. The metal solution was shaken on an orbital shaker at 200 rpm and 30 ℃. FBILS were separated from the solution by decantation. Residual metal concentration in the metal solutions by centrifugation at 3000 rpm for 5 min Supernatant was analysed for residual metal ions concentration was determined using flame atomic absorption spectrophotometer.
Effect of contact time and pH on metal ion biosorption For the determination of rate of metal biosorption by FBILS, the supernatant was analysed for residual metal ions after the contact period of 10, 20, 30, 60, 120, 240 and 360 min. The effect of pH on metal ions sorption by FBILS was determined by equilibrating the sorption at different pH values of 2, 3. 4, and 5.
Chemical and physical stability of FBILS For the purpose, FIBILS was shaken on an orbital shaker at different rotation speed for 2 days. Similarly, soaking of FBILS in buffer of various pH (2.0–12.0 for 20 days) was shaken on an orbital shaker at 200 rpm for 20 days had weight loss 20% of the FBILS were observed during this period.
data analysis q = V(Ci - Ceq)/M q is the metal uptake (mg metal ions /g dry weight of fungal biomass entrapped within sponge) V is the volume of metal solution (ml) Ci is the initial concentration of metal ions in the solution (mg/l) Ceq is the final concentration of metal ions in the solution M is the dry weight of fungal biomass
Fungal biomass immobilized within loofa sponge (b) (a) • natural loofa sponge covered with A. terrues biomass • artificial loofa sponge covered with A. terrues biomass
Effect of different phase on metal uptake by FBILS 100 ml single metal solution (6000mg/l) was contacted with different days of FBILS on orbital shaker at 200 rpm at 30 ℃ at pH3 for 30 min
effect of pH on metal uptake by FBILS Metal solution was contacted with 15 days of FBILS at optimal condition
Effect of temperature on metal biosorption by FBILS ℃ Metal solution was contacted with 15 days of FBILS at optimal condition
Effect of rotation rate on metal biosorption by FBILS Metal solution was contacted with 15 days of FBILS at optimal condition
Chemical stability of LIBCS soaking of FBILS in buffer of various pH (2.0–12.0 for 20 days)
physical stability of FBILS soaking of FBILS in pH7 buffer for 2 days
Loofa sponge is an effective immobilization carrier for the entrapment of A.terreus to produce FBILS. The biosorption capacity of FBILS for single metal decreased in the order Pb > Hg > Cd FBILS showed an excellent potential for the removal lead(II) from aqueous solution. FBILS showed an good physical and chemical stability.
