Removal of ammonnia-nitrogen in simulated NH_4~+-N wastewater with modified clinoptilolite

The Chinese natural clinoptilolite was modified by alkali fusion and hydrothermal treatment.The modified clinoptilolite was characterized with X-ray diffraction(XRD),inductively coupled plasma-atomic emission spectrometry(ICP-AES),and scanning electron microscopy(SEM).The orthogonal experiment with 5×6 factors showed that the temperature of hydrothermal treatment was the most significant factor for the modification of clinoptilolite.The modification processes led to the formation of the Na-P zeolite with lower Si/Al molar ratio,thereof their capacity for adsorbing NH+4-N was enhanced.Using 5 g of modified clinoptilolite,the removal rate of NH+4-N in 100 mL simulated wastewater(NH4Cl 1000 mg · L-1) was up to 77.8% under the optimum conditions.Moreover,the adsorption of NH+4-N on clinoptilolite is a rapid process,which accords with Langmuir isothermal adsorption model.