Treatment Of Nickel Ions In Waste Water By Complexation-Ultrafiltration Technology

Waste water containing heavy metal ions cause pollution to environment seriously, and it has great harmfulness to the human body and living beings. To deal with the heavy metal ions in waster water a kind of treatment methods are used at present, but all the methods have their own shortcomings. Membrane technology is a novel method to on dealing with the waste waster. Because of the advances of high efficiency and low energy consuming, easy to be operated and during the membrane filtration process there is no chemical reaction, membrane technology has became one of the most important method for waste water treatment.Complexation-ultrafiltration technology is a novel method for waste water treatment containing heavy metal ions treatment. This experiment has studied the treatment of Ni²⁺ in waste water by ultrafiltration membrane which molecule weight cut-off is 6K and the Polymer acrylic acid which synthesized in laboratory for the first time. To ultrafiltration membrane the pressure is one of the most important factors for its permeant flux. As shown in experiment, when the pressure increasing, the permeant flux increased. But too high pressure may cause damage to the ultrafiltration membrane, so a situated pressure must be selected. That's not only necessarily for membrane but also can reduce the energy consuming.The removal of Ni²⁺ in waster water by enhanced ultrafiltration was studied by binding it to polymer acrylic acid (PAA). In this process Ni²⁺ was firstly complexed by PAA in order to increase its molecular weight to having a size larger than the molecular weight cut-off (WMCO) of the membrane. That the PAA-Ni can be retained by the membrane and the permeate flux was purified to a certain extent from Ni²⁺. The effect of the pH level, the dosage of PAA, background electrolyte and other heavy metal ions were studied. The pH influences the rejection efficiency of Ni²⁺ in the way that it influences the binding strength of Ni²⁺ and PAA. The rejection efficiency of Ni²⁺ also has relationship with the initial concentration of PAA. The background electrolyte of NaCl and (NH₄)₂SO₄ have different effluence on the rejection coefficient of nickel ions. This is because the competition between background electrolyte and nickel ions complex with polymer acrylic acid are different to different background electrolytes.In order to recycle polymer acrylic acid in concentrated flux, the adsorption capacity of peat to Ni²⁺ in concentrated flux was studued. Peat is intended as an plentiful and inexpensive material to removal heavy metal ions in contaminated waters. During the experiment it can be seen that the adsorption capacity of peat was pH depended and the maximum adsorption capacity for Ni²⁺ was achieved at pH 4. After the adsorption of peat, polymer acrylic acid can be recycled and reused.