Adsorption and desorption of Cu (II) in wastewater by lignocellulose/ nano-montmorillonite composites

The lignocellulose/nano-montmorillonite (LNC/nano-MMT) composites prepared were taken as the adsorbent to research the adsorption and desorption properties of Cu (II) from copper-contained wastewater, which were synthesized by the chemical intercalation process of LNC and nano-MMT. The affecting parameters on the Cu (II) adsorption capacity by changing initial concentration of Cu (II) ion, solution pH value, adsorption temperature and adsorption time were studied in detail. The results show that the equilibrium adsorption capacity could be reached 322.56 mg·g^-1 under the optimal condition, 0.03 mol·L^-1 initial concentration of Cu (II) ion, 4.9 of the solution pH value, 50 ℃ of the adsorption temperature and 60 min of the adsorption time. The pseudo-second-order kinetic model could well describe the whole adsorption process, and the isotherm adsorption equilibrium is conformed to the Langmuir model. HNO₃ was used to perform desorption and regeneration experiments of LNC/nano-MMT composites. The results show that HNO₃ concentration 0.1 mol·L^-1, desorption temperature 40 ℃ and desorption time 30 min treated by ultrasonic wave, the satisfactory effect of desorption capacity is 283.15 mg·g^-1. The adsorption mechanism of LNC/nano-MMT was discussed in combination with the results of XRD, SEM and FTIR. The adsorption/desorption experiment displays that the adsorption capacity of LNC/nano-MMT is ideal for four cycles, so LNC/nano-MMT is confirmed as a high efficient adsorbent for recycling.