كليدواژه :
بيوچار پوشش داده شده , واجذب , كادميم , شكل هاي شيميايي
چكيده فارسي :
اﺳﺘﻔﺎده از ﺳﻄﻮح ﺑﯿﻮﭼﺎر ﺑﻪ ﻋﻨﻮان ﺑﺴﺘﺮي ﻣﻨﺎﺳﺐ ﺑﺮاي ﻗﺮارﮔﯿﺮي ﻧﺎﻧﻮذرات آﻫﻦ ﺻﻔﺮ ﻇﺮﻓﯿﺘﯽ ﻣﯽﺗﻮاﻧﺪ ﻋﻼوه ﺑﺮ اﻓﺰاﯾﺶ ﭘﺎﯾﺪاري و ﮐﺎﻫﺶ آﮔﻠﻮﻣﺮاﺳﯿﻮن اﯾﻦ ﻧﺎﻧﻮذرات، ﺳﺒﺐ اﻓﺰاﯾﺶ ﻓﺮاﯾﻨﺪﻫﺎي ﺟﺬﺑﯽ ﺑﯿﻮﭼﺎر ﺑﺮاي آﻻﯾﻨﺪهﻫﺎي ﻣﺨﺘﻠﻒ در ﻣﺤﯿﻂزﯾﺴﺖ ﺷﻮد. در اﯾﻦ ﭘﮋوﻫﺶ، ﺑﻘﺎﯾﺎي ﭘﻮﺳﺖ ﮔﺮدو )R(، ﺑﯿﻮﭼﺎر ﺑﻘﺎﯾﺎي ﭘﻮﺳﺖ ﮔﺮدو )B(، و ﺑﯿﻮﭼﺎر ﺑﻘﺎﯾﺎي ﭘﻮﺳﺖ ﮔﺮدو ﭘﻮﺷﺶ داده ﺷﺪه ﺑﺎ ﻧﺎﻧﻮذرات آﻫﻦ ﺻﻔﺮ ﻇﺮﻓﯿﺘﯽ )BN(، ﺑﻪ ﺻﻮرت ﺟﺪاﮔﺎﻧﻪ در ﺳﻪ ﺳﻄﺢ )0/5، 2، و 4%( ﺑﻪ ﯾﮏ ﺧﺎك آﻫﮑﯽ آﻟﻮده ﺷﺪه ﺑﻪ ﮐﺎدﻣﯿﻢ )200 ﻣﯿﻠﯽﮔﺮم ﮐﺎدﻣﯿﻢ ﺑﺮ ﮐﯿﻠﻮﮔﺮم ﺧﺎك(، اﺿﺎﻓﻪ و ﭘﺲ از اﻧﺠﺎم ﻓﺮاﯾﻨﺪ ﺧﻮاﺑﺎﻧﯿﺪن )90 روز(، رﻓﺘﺎر ﮐﺎدﻣﯿﻢ در ﺧﺎك ﺑﺎ اﺳﺘﻔﺎده از آزﻣﺎﯾﺸﺎت ﺳﯿﻨﺘﯿﮏ واﺟﺬب و ﺷﮑﻞﻫﺎي ﺷﯿﻤﯿﺎﯾﯽ، ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد، ﮐﺎرﺑﺮد BN ﺑﻪ ﻃﻮر ﻗﺎﺑﻞ ﻣﻼﺣﻈﻪاي ﻧﺴﺒﺖ ﺑﻪ دو ﺟﺎذب دﯾﮕﺮ ﺳﺒﺐ ﮐﺎﻫﺶ واﺟﺬﺑﯽ ﮐﺎدﻣﯿﻢ )ﮐﺎﻫﺶ 59/69، 80/16 و 80/5 ﺑﻪ ﺗﺮﺗﯿﺐ در ﺳﻄﻮح 0/5، 2، و 4%( در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ ﺷﺪ. ﻣﻘﺎدﯾﺮ ﭘﺎﯾﯿﻦ از ﭘﺎراﻣﺘﺮ Q1 )ﺑﺨﺶ ﻟﺒﺎﯾﻞ ﮐﺎدﻣﯿﻢ( در ﻣﺪل دو ﻣﺮﺣﻠﻪاي ﻣﺮﺗﺒﻪ اول ﺑﺮازش داده ﺷﺪه ﺑﺮ دادهﻫﺎي دوﻓﺎزي واﺟﺬﺑﯽ ﮐﺎدﻣﯿﻢ در ﺧﺎكﻫﺎي ﺗﯿﻤﺎر ﺷﺪه، ﻧﺸﺎن از اﺛﺮ ﺑﻬﯿﻨﻪ ﺑﻬﺴﺎزﻫﺎ )ﺑﻪ وﯾﮋه BN( در ﮐﺎﻫﺶ ﺑﺨﺶ ﻗﺎﺑﻞ دﺳﺘﺮس ﮐﺎدﻣﯿﻢ ﻧﺴﺒﺖ ﺑﻪ ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ داﺷﺖ. ﮐﺎرﺑﺮد ﻫﺮ ﺳﻪ ﺟﺎذب ﺳﺒﺐ ﮐﺎﻫﺶ درﺻﺪ ﻧﺴﺒﯽ دو ﺷﮑﻞ ﻣﺘﺤﺮك ﺗﺒﺎدﻟﯽ و ﮐﺮﺑﻨﺎﺗﯽ ﺷﺪه ﺑﻮد ﮐﻪ اﯾﻦ ﮐﺎﻫﺶ در ﺧﺎكﻫﺎي ﺗﯿﻤﺎر ﺷﺪه ﺑﺎ BN
ﺳﻄﻮح 2 و 4%( ﺑﻪ ﺻﻮرت ﻣﺸﻬﻮدي ﺑﯿﺶ از ﺳﺎﯾﺮ ﺗﯿﻤﺎرﻫﺎ ﺑﻮد. ﮐﺎﻫﺶ ﻓﺎﮐﺘﻮر ﺗﺤﺮك ﮐﺎدﻣﯿﻢ از 68/2% در ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ ﺑﻪ 35/51، 43/83 و 54/1% )ﻣﯿﺎﻧﮕﯿﻦ ﺳﻪ ﺳﻄﺢ( ﺑﻪ ﺗﺮﺗﯿﺐ در ﻧﻤﻮﻧﻪﻫﺎي ﺗﯿﻤﺎر ﺷﺪه ﺑﺎ B ،BN و R ﻧﺸﺎن از اﺛﺮﺑﺨﺸﯽ ﺑﺎﻻي ﺑﯿﻮﭼﺎرﻫﺎي ﭘﻮﺷﺶ داده ﺷﺪه در ﺗﺜﺒﯿﺖ ﮐﺎدﻣﯿﻢ ﻧﺴﺒﺖ ﺑﻪ B و R داﺷﺖ. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ، ﺑﯿﻮﭼﺎرﻫﺎي ﭘﻮﺷﺶ داده ﺷﺪه ﺑﺎ ﻧﺎﻧﻮذرات آﻫﻦ ﺻﻔﺮﻇﺮﻓﯿﺘﯽ، ﺑﻪ دﻟﯿﻞ ﺗﺠﻤﯿﻊ ﻓﺮاﯾﻨﺪﻫﺎي ﺗﺜﺒﯿﺖ دو ﻣﺎده ﺑﯿﻮﭼﺎر )ﻓﺮاﯾﻨﺪﻫﺎي ﺗﺒﺎدل ﯾﻮﻧﯽ، ﮐﻤﭙﻠﮑﺲ ﺳﻄﺤﯽ و رﺳﻮب ﺳﻄﺤﯽ ﯾﺎ رﺳﻮب ﻣﺠﺪد( و ﻧﺎﻧﻮذرات آﻫﻦ ﺻﻔﺮ ﻇﺮﻓﯿﺘﯽ )ﻓﺮاﯾﻨﺪﻫﺎي ﺟﺬب و ﺗﺸﮑﯿﻞ ﮐﻤﭙﻠﮑﺲ(، راﻧﺪﻣﺎن ﺑﺎﻻﺗﺮي در ﮐﺎﻫﺶ واﺟﺬﺑﯽ و ﺗﺤﺮك ﮐﺎدﻣﯿﻢ در ﺧﺎك آﻫﮑﯽ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻧﺴﺒﺖ ﺑﻪ ﺑﯿﻮﭼﺎرﻫﺎي ﻏﯿﺮﭘﻮﺷﺶ داده ﺷﺪه، ﻧﺸﺎن دادند.
چكيده لاتين :
Using biochar surfaces as a suitable substrate for placing nano-scale zero-valent iron (nZVI), in addition to
increase the stability and reduce the agglomeration of these nanoparticles, could improve the biochar sorption
mechanisms for various pollutants in environment. In this research, walnut-shell residues (R), walnut-shell
residues biochar(B), and walnut-shell residues biochar coated by nZNI (BN) were applied to a Cd-spiked (200
mg Cd kg-1 soil) calcareous soil at three levels (0.5, 2, and 4%); and after incubation process (90 days), soil Cd
behavior was examined using desorption kinetic and chemical fractionation experiments. The results showed
that application of BN compared with two other amendments significantly reduced Cd desorption (59.69%,
80.16% and 80.5%, respectively, at 0.5, 2 and 4% levels) compared to the control sample. The low values of
the Q1 parameter (labile form of Cd) in two-step first-order reactions model fitted on Cd two-phase desorption
data in treated soils indicated the positive effect of amendments (in particular BN) on reducing the available
Cd compared to the control sample. Application of all three amendments had reduced the relative percentage
of carbonate and exchangeable forms, as these reductions in BN-treated soils (2 and 4% levels) were obviously
more than the other treatments. Reduction of Cd mobility factor from 68.2% (in control sample) to 35.51, 43.83
and 54.1% in BN-, B-, and R-treated samples, respectively, showed the high effectiveness of BN as compared
to B and R treated soils. Based on the results of this study, the biochars coated with nZVI, due to the integration
of stabilization mechanisms of biochar (processes of ionic exchange, superficial complexes and surface
precipitation or co-perception) and nZVI (processes of sorption and complex formation), showed a higher
efficiency on Cd stabilization in soil samples compared to the none-coated biochar and raw organic residues.
