Fixed-bed adsorption performance and empirical modeling of cadmium removal using adsorbent prepared from the cyanobacterium Aphanothece sp cultivar

Water contamination by cadmium (Cd), which is a toxic heavy metal widely used in many industrial processes, is a pervasive environmental problem. This study investigated the removal of Cd by dry cyanobacterium Aphanothece sp cultivar in adsorption columns The effect of inlet Cd concentrations (1.00 - 4.85mg/L), flow rates (0.30-0.60 L/h) and bed height (4.6 -7.2 cm) on the breakthrough characteristics of the adsorption column was investigated. The maximum adsorption capacity and efficiency were found to be 8.20 mg/g and 89.07 %, respectively with a flow rate of 0.60 1411 and 4.85 mg/L inlet concentration of Cd. The fixed bed adsorption data were fitted to three well known fixed bed empirical models namely Thomas, Adam-Bohart and Yoon-Nelson. The experimental results well fitted with the models mentioned above with R-2 of greater than 0.98 at different conditions. The regeneration efficiency of benthic cyanobacterium Aphanothece sp cultivar based adsorbent was studied using 0.1 M HCl. Repetitive adsorption-regeneration experiment show that, at the end of the fifth cycle, the desorption efficiency decreased by 21%. Thus, further research is necessary to improve the reusability of dried biomass of cyanobacterium Aphanothece sp adsorbent. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study focused on investigating the removal of cadmium from contaminated water by cyanobacterium, and studied the impact of different conditions on the breakthrough characteristics of adsorption column. It was found that the cyanobacterium had high adsorption capacity and efficiency under specific conditions, but the regeneration efficiency needs further improvement.