Abstract
Calcium alginate (CA) beads as a green sorbent were easily fabricated in this study using sodium alginate crosslinking with CaCl2, and the crosslinking pathway was the exchange between the sodium ion of α-L-guluronic acid and Ca(II). The experimental study was conducted on Cu(II), Cd(II), Ni(II) and Zn(II) as the model heavy metals and the concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The characterization and sorption behavior of the CA beads were analyzed in detail via using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption experiments demonstrated that the CA beads exhibited a high removal efficiency for the selective adsorption of Cu(II) from the tetra metallic mixture solution and an excellent adsorption capacity of the heavy metals separately. According to the isotherm studies, the maximum uptake of Cu(II) could reach 107.53 mg/g, which was significantly higher than the other three heavy metal ions in the tetra metallic mixture solution. Additionally, after five cycles of adsorption and desorption, the uptake rate of Cu(II) on CA beads was maintained at 92%. According to the properties mentioned above, this material was assumed to be applied to reduce heavy metal pollution or recover valuable metals from waste water.
Highlights
In recent years, agriculture and the mining, chemical fertilizer, leather, battery and paper industries have developed vigorously, and the phenomenon of heavy metal wastewater directly or indirectly being discharged into the environment has become more and more serious, in developing countries [1,2]
The results revealed that after five cycles, the Calcium alginate (CA) beads still had selective adsorption for Cu(II) and the adsorption capacity was more than 92%
A spherical CA bead with a diameter of 3 mm was prepared by crosslinking the hydroxyl and carboxyl groups of sodium alginate with Ca(II) to form an insoluble hydrogel; there were a large carboxyl groups of sodium alginate with Ca(II) to form an insoluble hydrogel; there were a large number of active sites in the porous honeycomb structure for metal ions to attach
Summary
Agriculture and the mining, chemical fertilizer, leather, battery and paper industries have developed vigorously, and the phenomenon of heavy metal wastewater directly or indirectly being discharged into the environment has become more and more serious, in developing countries [1,2]. In addition to the methods reported above, adsorption was selected to treat copper-containing wastewater due to its advantages, such as low initial cost and process simplicity [10,11]. For the treatment of heavy metals in wastewater, availability and cost effectiveness play an important role in the synthesis of the adsorbents. This has made people pay attention to abundant, renewable and environmentally-friendly marine resources, such as bio-sorbents [12]. The alginate beads as a green sorbent were fabricated with the Ca(II) crosslink, maintaining the high efficiency of the selective recovery of Cu(II) from the metal mixtures and the good adsorption of the heavy metals separately. The alginate beads showed good reusability after five rounds of simple sorption–desorption procedures
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
