How to modify natural clinoptilolite
Weigh 10g of clinoptilolite powder with 20-40 mesh (natural zeolite rock becomes powdered zeolite through a mill), add 100mL of 20% NaCl solution, boil with an electric stove, pour off the turbid liquid, then add 100mL of preheated brine, and boil it with an electric stove. . 5h, the same operation as before, and finally rinse with distilled water to cool the zeolite to room temperature to complete the modification.
The modified sodium-type natural zeolite powder is packed into a φ5mmX300mm exchange column and washed with distilled water until there is no Cl- in the effluent. Then use ammonia-nitrogen wastewater with a known pH value of NH+4 concentration to flow through the exchange column at a certain flow rate, stop passing the wastewater when it reaches a certain scale, measure the NH+4 concentration of the wastewater in the volumetric flask, and pass the NH4+ concentration difference in the wastewater before and after passing.
Then the total exchange capacity of natural zeolite powder for ammonium ions can be calculated. Changing the pH value of the ammonia nitrogen wastewater, repeating the above steps, the total exchange capacity of the natural zeolite powder to the ammonium ions in the ammonia nitrogen wastewater at different pH values can be measured.
The circulation test uses sodium chloride solution as the eluent. Under the comprehensive conditions of wastewater pH of 5, adsorption temperature of 20°C, the adsorption rate of 0.0027m/s, elution temperature of 75°C, and elution rate of 0.08cm/s, the researchers conducted multiple sets of experiments.
The original wastewater is 246mg/L35L, and the treated wastewater is 21.3mg/L35L. It was eluted with a 1.5L saturated NaCl aqueous solution to produce 6300mg/L 1.5L wastewater. The experiment uses two eluents (sodium chloride solution and calcium oxide emulsion) for elution.
The results prove that calcium zeolite also has a good ability to remove ammonia, and the ammonia recovery rate can reach 95.6%.
Using natural clinoptilolite powder to treat ammonia nitrogen wastewater, under the condition of wastewater concentration pH = 5, the average total exchange capacity of natural zeolite powder reaches 12.96 mg/g, and the exchange capacity decreases with the increase of pH.
When high-speed, low-temperature treatment of ammonia nitrogen wastewater is beneficial to improve the adsorption capacity of natural clinoptilolite powder. When low-speed, high-temperature treatment of ammonia nitrogen wastewater is beneficial to improve the elution capacity (regeneration capacity) of natural clinoptilolite powder.
The test showed that the concentration of wastewater after treatment dropped from 246mg/L to 21.3mg/L, and the removal rate of ammonia nitrogen reached 91.3%, which reached the national standard.
The experiment uses two eluents (sodium chloride solution and calcium oxide emulsion) for elution. The results prove that zeolite also has a good ability to remove ammonia, and the ammonia recovery rate can reach 95.6%.