The easy-recoverable 3D Ni/Fe-LDH-SA gel ball encapsulated by sodium alginate is used to remove Ni2+ and Cu2+ in water samples

Heavy metals in the water environment seriously threaten human health and the ecological environment. As an effective method for removing heavy metals in water, adsorption has attracted wide attention. Traditional LDHs materials are difficult to recover as adsorbents. This study provides a new type of adsorption material for Ni/Fe-LDH coated with sodium alginate(SA) synthesized by a simple hydrothermal method and treated with NaOH. Obtain the alkalized adsorption material alk-Ni/Fe-LDH-SA. It was characterized by SEM, XRD, FTIR, TGA and XPS, and its adsorption effect on Ni(II) and Cu(II) was studied. The experimental results show that the prepared Ni/Fe-LDH-SA adsorbent has an adsorption capacity of 182.8 mg/g for Ni2+ and 196.2 mg/g for Cu2+ at 25℃. It has good performance when pH ≥ 7, and after four cycles, the removal rate of the two ions remains above 80%. The analysis mechanism shows that the removal process is mainly through physical adsorption precipitation, electrostatic adsorption, ion exchange, and chelation. Compared with traditional adsorbents, the adsorbent prepared in this study is easy to be recycled and reused, and has potential application value to other heavy metal ions. It is a promising adsorbent material.