Adsorptive removal of cadmium ions by Spirulina platensis dry biomass

Abstract

Cadmium is one of the most toxic substances found in aquatic ecosystems. This metal tends to accumulate in photosynthetic plants and fish and is transferred to humans causing many diseases. It has to be removed from our environment to reduce any health risks. Dry biomass of the microalga (cyanobacterium) Spirulina platensis was used as biosorbent for the removal of cadmium ions (Cd(2+)) from aqueous solutions. The effects of different levels of pH (3-9), biomass concentration (0.25-2 g), temperature (18-46 °C), metal concentration (40-200 mg/l) and contact time (30-120 min) were tested. Batch cultures were carried out in triplicate in an orbital shaker at 150 rpm. After centrifuging the biomass, the remaining levels of cadmium ions were measured in the supernatant by Atomic Absorption Spectrometer. Very high levels of removal, reaching up to 87.69% were obtained. The highest percentage of removal was reached at pH 8, 2 g of biosorbent, 26 °C, and 60 mg/l of cadmium concentration after 90 min of contact time. Langmuir and Freundlich isotherm models were applied to describe the adsorption isotherm of the metal ions by S. platensis. Langmuir model was found to be in better correlation with experimental data (R (2) = 0.92). Results of this study indicated that S. platensis is a very good candidate for the removal of heavy metals from aquatic environments. The process is feasible, reliable and eco-friendly.

ADSORPTION OF Cd AND Pb USING BIOMASS OF MICROALGAE SPIRULINA PLATENSIS

“…This result was the same as reported by Al-Homaidan et al [21]. The control of pH in culture medium is very important to maintain the balance of cell growth of S. platensis.…”

“…This was supported by Al-Homaidan et al [22] which reached up to 91% lead adsorption at acidic pH 3, while less adsorption of lead obtained in this study, only 84.3% at pH 8.79.…”

“…Many studies had been carried out using S. platensis on heavy metal removal [9], [20], [21]- [23]. However, none of them observed the effectsof heavy metals to density and cell size of microalgae biomass.…”

“…However, none of them observed the effectsof heavy metals to density and cell size of microalgae biomass. Moreover, dead cells of S. platensis were mostly used in many studies [20], [21], [23], but less studies used living cells.…”

FABRICATION OF PES/MnO MIXED MATRIX MEMBRANES FOR CADMIUM REMOVAL

“…As can be seen, better Cd removal efficiency was found to be in alkaline solution. The optimum Cd removal was observed between pH 9 to pH 11 for the MnO 2 /PES-2.0 membrane attributed to the increase in the electrostatic attraction between the positively charge Cd 2+ ions and the negative charged binding sites of the functional group present on the cell surface which is similar to the reported by Al-Homaidan et al and Adhiya et al [11,12]. …”