Abstract
Wastes are the sustainable sources of raw materials for the synthesis of new adsorbent materials. This study has as objectives the advanced capitalization of fly ash, by sulphuric acid activation methods, and testing of synthesized materials for heavy metals removal. Based on the previous studies, the synthesis parameters were 1/3 s/L ratio, 80 °C temperature and 10% diluted sulphuric acid, which permitted the synthesis of an eco-friendly adsorbent. The prepared adsorbent was characterized through SEM, EDX, FTIR, XRD and BET methods. Adsorption studies were carried out for the removal of Cd2+ ions, recognized as ions dangerous for the environment. The effects of adsorbent dose, contact time and metal ion concentrations were studied. The data were tested in terms of Langmuir and Freundlich isotherm and it was found that the Langmuir isotherm fitted the adsorption with a maximum adsorption capacity of 28.09 mg/g. Kinetic data were evaluated with the pseudo-first-order model, the pseudo-second-order model and the intraparticle diffusion model. The kinetics of cadmium adsorption into eco-friendly material was described with the pseudo-second-order model, which indicated the chemisorption mechanism.
Highlights
The presence of different pollutants in water that are characterized by their non-biodegradable nature can affect the environment and humans’ health [1,2,3]
The adsorbent dose had an effect on the adsorption process: A higher dose led to a decrease in adsorption capacity
It was found that the adsorption process is dependent on the initial concentration
Summary
The presence of different pollutants in water that are characterized by their non-biodegradable nature can affect the environment and humans’ health [1,2,3]. Heavy metals occur in a significant number of places; this type of pollutant represents one of the biggest environmental problems [4,5]. Out of all possible removal methods, adsorption is one of the most applied techniques for treating contaminated waters due to some advantageous criteria, such as high performance, low cost, easy operation, wide pH range, etc. Out of all the available adsorbents, activated carbon and zeolites can be used; for low cost adsorbents, fly ash, modified ash, agricultural wastes, etc., are considered [7,8,9]. As a result of coal combustion, fly ash is found in large quantities and it has been reported that this fact causes serious environmental problems [10,11]; it must be addressed [12,13]
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