بررسي سينتيك و همدماي جذب نيترات و آمونيوم از محلول آبي با استفاده از زغال زيستي ني

Study of Ammonium and Nitrate Adsorption Kinetics and Isotherm by Common reed (Phragmites australis) Biochar from Aqueous Solution

نيترات و آﻣﻮﻧﯿﻮم از آﻻﯾﻨﺪهﻫﺎي ﻣﻬﻢ اﮐﻮﺳﯿﺴﺘﻢﻫﺎي آﺑﯽ ﻫﺴﺘﻨﺪ ﮐﻪ ﺳﺒﺐ اﯾﺠﺎد ﻏﻨﯽ ﺷﺪن ﻣﻨﺎﺑﻊ آﺑﯽ ﻣﯽﺷﻮﻧﺪ. اﺳﺘﻔﺎده از ﺟﺎذبﻫﺎي ﻃﺒﯿﻌﯽ، ارزان و دوﺳﺘﺪار ﻣﺤﯿﻂزﯾﺴﺖ ﻣﯽﺗﻮاﻧﺪ راﻫﮑﺎر ﻣﻨﺎﺳﺒﯽ ﺑﺮاي ﺣﺬف ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم از ﻣﺤﯿﻂﻫﺎي آﺑﯽ ﺑﺎﺷﺪ. ﻫﺪف از اﯾﻦ ﭘﮋوﻫﺶ، ﺑﺮرﺳﯽ ﺗﻮاﻧﺎﯾﯽ زﻏﺎل زﯾﺴﺘﯽ ﮔﯿﺎه ﻧﯽ )Phragmites australis( در ﺟﺬب ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم از ﻣﺤﻠﻮل آﺑﯽ ﺑﻮد. ﺑﺮاي اﯾﻦ ﮐﺎر، زﻏﺎل زﯾﺴﺘﯽ ﻧﯽ در دﻣﺎي 500 درﺟﻪ ﺳﻠﺴﯿﻮس ﺗﻬﯿﻪ و وﯾﮋﮔﯽﻫﺎي آن اﻧﺪازهﮔﯿﺮي ﺷﺪ. آزﻣﺎﯾﺶﻫﺎي ﺟﺬب ﺳﻄﺤﯽ و ﺗﺄﺛﯿﺮ ﺑﺮﺧﯽ از ﭘﺎراﻣﺘﺮﻫﺎي ﻣﺆﺛﺮ ﺑﺮ ﻓﺮاﯾﻨﺪ ﺟﺬب ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺑﻪوﺳﯿﻠﻪ زﻏﺎل زﯾﺴﺘﯽ ﻧﯽ ﺷﺎﻣﻞ ﻏﻠﻈﺖ اوﻟﯿﻪ، زﻣﺎن ﺗﻤﺎس، pH و ﻣﻘﺪار زﻏﺎل زﯾﺴﺘﯽ، ﺑﻪﺻﻮرت ﭘﯿﻤﺎﻧﻪاي ﺑﺮرﺳﯽ ﺷﺪ. ﺟﺬب ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺗﻮﺳﻂ زﻏﺎل زﯾﺴﺘﯽ ﻧﯽ ﺑﻪﺗﺮﺗﯿﺐ ﭘﺲ از ﮔﺬﺷﺖ 480 و 240 دﻗﯿﻘﻪ ﺑﻪ ﺗﻌﺎدل رﺳﯿﺪ. pH ﺑﻬﯿﻨﻪ در ﺣﺬف ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺑﻪﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ 3 و 9 ﺑﻮد. ﮐﺎراﯾﯽ ﺣﺬف ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺑﺎ اﻓﺰاﯾﺶ زﻣﺎن ﺗﻤﺎس و ﻣﻘﺪار ﺟﺎذب اﻓﺰاﯾﺶ ﯾﺎﻓﺖ. ﻣﺪل ﺳﯿﻨﺘﯿﮏ ﺷﺒﻪ درﺟﻪ دوم ﺗﻮﺻﯿﻒ ﻣﻨﺎﺳﺒﯽ از ﻓﺮاﯾﻨﺪ ﺟﺬب آﻣﻮﻧﯿﻮم )0/99= r2( و ﻧﯿﺘﺮات )0/97= r2( اراﺋﻪ داد. ﻣﺪلﻫﺎي ﻻﻧﮕﻤﻮﯾﺮ )0/99 r2 و ﻓﺮوﻧﺪﻟﯿﭻ )0/99= r2( ﺑﻪﺗﺮﺗﯿﺐ ﺑﻬﺘﺮﯾﻦ ﺑﺮازش را ﺑﺮاي دادهﻫﺎي آﻣﻮﻧﯿﻮم و ﻧﯿﺘﺮات ﻧﺸﺎن دادﻧﺪ. ﺑﻪﻃﻮرﮐﻠﯽ ﻧﺘﺎﯾﺞ اﯾﻦ ﭘﮋوﻫﺶ ﻧﺸﺎندﻫﻨﺪه ﺗﻮاﻧﺎﯾﯽ ﺑﺎﻻي زﻏﺎل زﯾﺴﺘﯽ ﻧﯽ ﺑﺮاي ﺟﺬب ﻧﯿﺘﺮات )73/5 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮔﺮم( و آﻣﻮﻧﯿﻮم )42/6 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮔﺮم( ﺑﻮد. ﺑﻨﺎﺑﺮاﯾﻦ زﻏﺎل زﯾﺴﺘﯽ ﻧﯽ ﭘﺲ از ﺟﺬب ﻧﯿﺘﺮات و آﻣﻮﻧﯿﻮم ﺑﻪدﻟﯿﻞ ﻇﺮﻓﯿﺖ ﻣﻨﺎﺳﺐ در ﺗﺄﻣﯿﻦ ﺑﺨﺸﯽ از ﻧﯿﺘﺮوژن ﻮردﻧﯿﺎز ﮔﯿﺎﻫﺎن، ﭘﺘﺎﻧﺴﯿﻞ ﺧﻮﺑﯽ ﺑﻪﻋﻨﻮان ﯾﮏ اﺻﻼحﮐﻨﻨﺪه ﺧﺎك دارد.

Nitrate and ammonium are the major contaminants of aquatic ecosystem causing eutrophication in water resources. Application of natural, inexpensive and ecofriendly adsorbents can be a useful approach for ammonium and nitrate removal from aqueous solutions. The aim of this study was to investigate the ability of common reed biochar to absorb nitrate and ammonium from aqueous solution. For this purpose, the common reed biochar was prepared at 500°C and its characteristics were measured. The effect of initial concentration, contact time, pH and biochar dosage on nitrate and ammonium adsorption was studied using batch experiment. Adsorption of nitrate and ammonium by biochar reached to equilibrium after 480 and 240 minutes, respectively. The optimal pH for removal of nitrate and ammonium was 3 and 9, respectively. The efficiency of nitrate and ammonium removal increased with increasing contact time and dose of biochar. The pseudo second order kinetic model provides a good description for the adsorption process of ammonium (r2=0.994) and nitrate (r2 =0.970). Langmuir and Freundlich isotherms showed the best fit for ammonium and nitrate experimental data, respectively. Generally, the common reed biochar showed a high capacity for adsorption of nitrate (73.52 mg g-1) and ammonium (42.55 mg g-1). Therefore, the exhausted adsorbents containing ammonium and nitrate has a good potential as a soil conditioner that can supply part of plant's need to nitrogen.