Cadmium biosorption by polyvinyl alcohol immobilized recombinant Escherichia coli.
Recombinant Escherichia coli expressing human metallothionein protein was immobilized with polyvinyl alcohol (PVA) for the removal of cadmium from solution. The adsorption ability was strongly affected by pH with optimal performance at pH 5.0, while it was less sensitive to temperature over the range of 20-42 degrees C. The adsorption kinetics and equilibrium of PVA-immobilized cells was best described by pseudo-second order model and Langmuir isotherm, respectively. Over the Cd concentrations range of 10-150 mg/l, PVA-cells had the highest Cd removal percentage (82.7%) at 10mg Cd/l and a biomass loading of 15.4 wt.%. Better adsorption ability was obtained when biomass loading was increased, as the highest adsorption capacity of 4.29 mg/g was achieved at 33.0 wt.% of biomass (initial Cd concentration=100mg/l). An aqueous solution of 0.01 M Na(3)NTA displayed the best desorption efficiency (57-89%) for four A/D cycles, while 51-61% of the original adsorption capacity was retained after regeneration.
Kao
Wei-Chen
WC
Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Wu
Jane-Yii
JY
Chang
Chia-Che
CC
Chang
Jo-Shu
JS
D000327:Adsorption; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000302:isolation & purification*; D018914:Cells, Immobilized; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008668:Metallothionein / Q000235:genetics; D011142:Polyvinyl Alcohol; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
D014874:Water Pollutants, Chemical; D002104:Cadmium; D011142:Polyvinyl Alcohol; D008668:Metallothionein