Study On The Preparation And Characters Of Cu(II) Ion Imprinted Magnetic Biosorbent

Copper-containing wastewater is abroad and harmful to human being health and natural environment, so it is necessary to treat it. In this paper, a Cu(â…¡) ion imprinted magnetic biosorbent (Cu(â…¡)-IMB) was synthesized by using Cu²⁺ as imprinted ion, chitosan (CS) as imprinted matrix, fungal mycelium as core, nano-Fe₃O₄ as magnetic component. It was crosslinked by epichlorhydrin (ECH) and fixed by tripolyphoshate sodium, using in copper-containing wastewater treatment. Results showed that the main advantages of this new adsorbent were: (1) it is low cost that can be synthesized in large quantity with waste fungal mycelium from industry. (2) The adsorption capacity is improved by imprinting technique for the target molecule due to molecular geometry. (3) The easy separation of magnetic biosorbent from treated solution can be achieved by a magnetic field.The influencing reaction conditions during preparation of Cu(â…¡)-IMB were firstly optimized by response surface method (RSM) in order to get its best adsorption capacity. Results showed that the key factors to affect the adsorption capacity were the dosage of ECH, nano-Fe₃O₄ and imprinted Cu²⁺during the prepared process, and they had alternating relations. The affections of nano-Fe₃O₄ and imprinted Cu²⁺ on adsorption were right and most marked. The optimum prepared conditions were: mycelium 2g,CS0.2g, mixing equably at 30℃for 3.0h, fixing by 6mL 2.5% tripolyphoshate sodium for 8.0h. Cu²⁺ of CuSO₄ as imprinted template. The adding dosages were 2.99g ECH, 0.505g Fe₃O₄ and 25.245mg imprinted Cu²⁺.SEM, EDX, ICP, FT-IR, XRD and VSM were used to study the structure identification. Results showed that the shape of Cu(â…¡)-IMB was irregular, the surface was loosen and had lots of interspaced structure. There were plenty of groups favorable for heavy metal adsorption. The specific area and the pore volume improved greatly compared with pure mycelium and non-imprinted magnetic biosorbent (NIMB). Fe₃O₄ was embedding in the biosorbent successfully during preparation but the crystal was not changed, and disturbed asymmetrically.Cu(â…¡)-IMB kept supermagntic and magnetic character parameters were different with varied Fe₃O₄ dosages.Taking Cr⁶⁺,Zn²⁺,Ni²⁺ as comparing ions, the adsorption characters of Cu²⁺on Cu(â…¡)-IMB was studied and compared with the other prepared adsorbents. The mechanism strength, anti-acidity ability and magnetic settlement character were also measured. The results of adsorption character study showed that pH is the key factor that affects adsorption capacity. The optimum pH was 5.0 of Cu(â…¡)-IMB for Cu²⁺, Zn²⁺, Ni²⁺ adsorption and 4.0 for Cr⁶⁺ adsorption. The adsorption of Cu²⁺, Zn²⁺, Ni²⁺ and Cr⁶⁺on Cu(â…¡)-IMB, NIMB, CMB and MB in solution fit the second order kinetic model. The adsorption processes were controlled by both film and pore diffusion. The adsorption equilibrium data can be described in terms of the Langmuir or Freundlich isotherm. The adsorption speed of Cu²⁺ on the Cu(â…¡)-IMB was the fast and the adsorption equilibrium time was short for 6.0h. The adsorption speed of Cu²⁺ onto the Cu(â…¡)-IMB was the fast and was 33% higher than that of NIMB with K₂ was 4.432×10^-3((g/mg)/min).The diffuse coefficient was biggest of 0.97223 (mg/g)/min^1/2.Cu(â…¡)-IMB had strong adsorption capacity and high adsorption selectivity for Cu²⁺, single saturated adsorption capacity calculated from Langmuir equption was 68.02mg/g , but had no adsorption selectivity for Zn²⁺, Ni²⁺ and Cr⁶⁺, and its adsorption characters were better than that of NIMB.Thermodynamics study showed that the adsorption was endothermic reaction and spontaneous thermodynamically favorable. It was mainly governed by physisorption and the degrees of freedom increased during the adsorption. Cu(##)-IMB showed good magnetic settlement character under additional magnetic field. The settlement time shortened of 94% and settlement efficiency improved of 15% compared to non-magnetic adsorbent. The adsorption capacity, mechanism strength,joined degree and anti-acidity ability was high after the synthesis process. Adsorption competition affection was conducted in binary or multi-mixture solution system. The experiments showed that binary adsorption system experiments proved that disturbing ability for Cu²⁺ increased with the increasinginitial concentration of differentions. The order of compete adsorption capacity of heavy metals in solution on Cu(â…¡)-IMB and NIMB in turns was Zn²⁺>Ni²⁺> Cr⁶⁺.Cu(â…¡)-IMB still had high adsorption selectivity for Cu²⁺ and also fit Langmuir model although there were competing ions. In multi-ions solution, the adsorption capacity of Cu(â…¡)-IMB was higher than NIMB and had sole adsorption character. Cooperated competing effect on Cu²⁺of Zn²⁺ and Ni²⁺ was greater than that of Ni²⁺ and Cr²⁺. Adsorption mechanism analyses showed that -NH, -OH and heavy metals formed conjugated structure. Non-crystal structure of Cu(â…¡)-IMB and crystal model of Fe₃O₄ were not effected and it still kept the original magnetism. The desorption conditions was desorption by 0.1M EDTA for 20 minute and regenerated for 1.0h by NaOH. The results showed that Cu(â…¡)-IMB could be reused for more five times.A forecasting and controlling model of operational parameters was established innovatively based on BP nerve cell theory of Cu²⁺adsorption effect factors. Simulated results by the simulation model analysis were basically consistent with experimental value. This means to start an effective way for fixed quantify study of adsorption experiment. This indicated that some designs, choice of operational parameters, prediction of run effect could be finished on computer by the simulation model. This provided an effective way for on-line control in adsorption process.