A Study On The Treatment Of Electroplating Waste Water Using Zeolite

Zeolite have a three-dimensional structure constituted by (Si,Al)O4 tetrahedra connected by all their oxygen vertices forming channels where H2O molecules and exchangeable cations counterbalancing the negative charge generated from the isomorpHous substitution are present. It was concluded by some other people that the ion-exchange capacity of the nature zeolite can be increased more times, if they are activated.Through Jar test, we find that natural zeolite obtained in Jinhua Zhejiang can be activated by a series process at 25-30 . First, 100ml 0.05-0.1N HC1 solution added to 10g natural zeolite, shaking on a rotary shaker(140 tums/min)for 12 hours. Then the 10g zeolite soaks in 100ml 5% NaCl solution, shaking on a rotary shaker(140 turns/min)for 12 hours. The ion-exchange capacity of the natural zeolite for zinc increased from Img/g to more than 3.2mg/g of activated zeolite. Activeted zeolite can be regenerated with 20% NaCl solution when they have not ion-exchange capacity. The regeneration efficioucy is 92%,the 10g zeolite needed volumes of regenerant solution is 50ml,the second ion-exchange capacity is 95% of the first one.By the on-the-spot experiments in the electroplating waste water which have been treated by pHysicochemical treatment, these conclusion are got:1. The water head loss is low. When water flow through 0.9m-thick zeolite, flow rate is 2.6m/h, 4.2 m/h, 7.4 m/h, and the water head loss is 3-5cm,8-12cm,and 15-20cm, respectively.2. The selectivity sequence of the zeolite is Zn2+>Ni2+. The effluence concentration is relate to the tough time of water and zeolite. When flow rare is 2.6m/h, the touch time is about 10min, the effluence Ni2+ concentration meets the legislation requirements in 12hours.3. After 12 hours,zeolite needs regeneration with NaCl solution. The weight of NaCl in regeneration is about 1/4 of the weight of zeolite. So much NaCl in solution, the regeneration concentration including 8%, 5% and 3%, and the regeneration flow rate including 1.25m/h, 2.5m/h and 3.75m/h have no influence on the regeneration efficiency, the regeneration efficiency in better at any conditions.