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Wong Mui F. Chua Hong Lo Waihung Leung Chu K. Yu Peter H. F. 《Applied biochemistry and biotechnology》2001,91(1-9):447-457
Studies were conducted toinvestigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir
isotherm model very well with a maximum biosorption capacity (qmax) of 36.5 mg of Cu2+/gofdry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics
for copper, Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH un til 6.0. In multim
etal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu−Pb>Ni−Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl−, SO
4
2−
, and NO3/− (0–500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial
copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from
effluents. 相似文献
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Wong Phoeby A. L. Chua Hong Lo Waihung Lawford Hugh G. Yu Peter H. 《Applied biochemistry and biotechnology》2002,98(1-9):655-662
Polyhydroxyalkanoates, biodegradable plastics with the desired physical and chemical properties of conventional synthetic
plastics, are extensively investigated. In this study, specific bacterial strains produced specific copolymers from food waste.
Copolymers of HB and HV (poly[3-hydroxybutyrate-co-3-hydroxyvalerate]) were obtained using various ratios of butyric acid
(C4) and valeric acid (C5) as carbon sources. The C4 to C5 ratio affected the melting points of the copolymers. Melting and glass transition temperatures and many other thermal properties
are important parameters relative to in-service polymer applications. Higher ratios of butyrate to valerate gave higher melting
points. When a mixed culture of activated sludge was employed to produce copolymers using food wastes as nutrients, the obtained
copolymers showed various monomer compositions. Copolymers with a higher portion of HV were obtained using soy waste; copolymers
with less HV were obtained using malt wastes. Pure strains, (i.e., Alcaligenes latus DSM 1122, and DSM 1124, Staphylococcus spp., Klebsiella spp.) produced specific copolymers from food waste. Only Klebsiella spp. produced different copolymers; the ratios of HB:HV were 93:7 and 79:21 from malt waste and soy waste, respectively.
The other strains produced polymers of 100% HB. Selecting industrial food wastes as carbon sources can further reduce the
cost of producing copolymers.
Open Laboratory of Chirotechnology of the Institute of Molecular Technology for Drug Discovery and Synthesis
The University Grants Committee Area of Excellence Scheme, Hong Kong 相似文献
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Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined
at pH 5.0 and initial metal concentration of 100 mg/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity. The lead and copper biosorption of this
strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q
max) reaching 271.7mg of Pb2+/g of dry cell and 46.8 mg of Cu2+/g of dry cell at pH 5.0. Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased
with increasing pH from 2.0 to 7.0. A mutual inhibitory effect was observed in the lead-copper system because the presence
of either ion affected the sorption capacity of the other. Unequal inhibitions were observed in all the nickel binary systems.
The increasing order of affinity of the three metals toward P. pseudoalcaligenes was Ni<Cu<Pb. The metal biosorptive potential of these isolates, especially P. pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents. 相似文献
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Waihung Lo Lau Mei Ng Hong Chua Peter H. F. Yu Shirley N. Sin Po-Keung Wong 《Applied biochemistry and biotechnology》2003,107(1-3):581-591
Batch biosorption experiments were conducted to investigate the removal of Cu2+ ions from aqueous solutions by a series of bacterial strains isolated from a local activated sludge process. The characteristics
of 12 isolates were identified and examined for their ability to bind Cu2+ ions from aqueous solution. Among the isolates, two species exhibited biosorption capacity >40 mg of Cu/g of dry cell. Isotherms
for the biosorption of copper on bacterial cells were developed and compared, and the equilibrium data fitted well to the
Langmuir and Freundlich isotherm models. The biosorption of copper increased significantly with increasing pH from 2.0 to
6.0 regardless of the species. More than 90% of copper sorbed on the cells of Bacillus sp. could be recovered by washing with 0.1 M HNO3 for 5 min. The performance of two different desorption processes was also tested and compared. The results show that five
biosorption and desorption cycles are a better operation process than five successive biosorptions followed by one desorption
to remove and recover copper from aqueous solution. The biosorbent could be used for at least five biosorptions and desorption
cycles without loss of copper removal capacity. It can be concluded that the activated sludge or sludge-isolated bacteria
could be a potential biosorbent for copper removal. 相似文献
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