Abstract
Graphene materials have attracted increasing interest in water remediation. In this study, magnetic graphene oxide (MGO) was prepared through the modified Hummers method and the adsorption behaviors of cadmium were investigated. Firstly, the sorption kinetics, isotherms, as well as the effects of pH were investigated. Then, fractional factorial design (FFD) was used to optimize the effects of pH, temperature, time, initial concentration of cadmium ion and NaCl on cadmium adsorption. The results indicate that MGO could effectively remove cadmium ions from an aqueous solution and the sorption data could be described well by pseudo-second-order and Freundlich models, showing that the adsorption rate of cadmium ions on MGO is multilayer adsorption and dominated by the chemical adsorption. According to the FFD results, the maximum adsorption capacity of cadmium ions was 13.169 mg/g under the optimum condition of pH value 8, 45 °C, contact time 60 min, initial cadmium concentration of 70 mg/L and NaCl concentration of 100 mg/L. Higher levels of the pH value, temperature and initial cadmium concentration are beneficial to the adsorption process. These results are important for estimating and optimizing the removal of metal ions by MGO composite.
Highlights
In recent years, with the rapid development of industry, arbitrary discharge of waste water has caused serious heavy metal pollution
We found that the oxygen-containing groups on the surface of the Graphene oxide (GO) have hydrophilic properties and are not separated from the solution after adsorption [11]
magnetic graphene oxide (MGO) was synthesized from natural graphite powder following a modified Hummers method according to previous studies [2,17]
Summary
With the rapid development of industry, arbitrary discharge of waste water has caused serious heavy metal pollution. Cadmium is a very toxic heavy metal and is widely used in electroplating, coating and metallurgy industries [2]. Cadmium can enter the body through respiratory and digestive systems, endangering human health [3]. Various diseases such as emphysema, kidney damage, diabetes, cardiovascular disorders and bone malformations are associated with cadmium ion hazards [4,5,6]. Cadmium ions have toxic effects on plants [7]. Cadmium that is absorbed by plants can destroy various dehydrogenases of plants, inhibiting plant growth and even causing plant death
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