بررسي تاثير بيوچارهاي حاصل از بقاياي گندم و ذرت بر جذب روي در محلول‌هاي آبي

Investigation of Effects of Bio Chars Derived from Wheat and Corn Straw on Zinc Adsorption in Aqueous Solutions

زﻣﯿﻨﻪ و ﻫﺪف: در ﺳﺎلﻫﺎي اﺧﯿﺮ، ﺑﺮاي ﮐﻨﺘﺮل آﻟﻮدﮔﯽ ﻣﺤﻠﻮلﻫﺎي آﺑﯽ ﺣﺎوي ﻓﻠﺰات ﺳﻨﮕﯿﻦ، اﺳﺘﻔﺎده از ﺑﯿﻮﭼﺎر ﺑﻪ ﻋﻨﻮان ﺟﺎذب، ﻣﻮرد ﺗﻮﺟﻪ ﭘﮋوﻫﺶﮔﺮان ﻗﺮارﮔﺮﻓﺘﻪاﺳﺖ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﮐﺎراﯾﯽ ﺑﯿﻮﭼﺎر ﮐﺎهﮔﻨﺪم و ﮐﺎهذرت درﺟﻬﺖ ﺣﺬف روي از ﻣﺤﻠﻮلﻫﺎي آﺑﯽ ﺗﺤﺖ ﺗﺎﺛﯿﺮ ﻓﺎﮐﺘﻮرﻫﺎي ﻣﺨﺘﻠﻒ ﻣﺎﻧﻨﺪ pH ، زﻣﺎنﺗﻤﺎس، ﻣﻘﺪار ﺟﺎذب و ﻏﻠﻈﺖ ﻣﺎده ﺟﺬبﺷﻮﻧﺪه ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮارﮔﺮﻓﺖ. روش ﺑﺮرﺳﯽ: ﺟﻬﺖ ﺗﻮﺻﯿﻒ اﯾﺰوﺗﺮم ﺟﺬب از ﻣﺪلﻫﺎي ﻻﻧﮕﻤﻮﯾﺮ و ﻓﺮوﻧﺪﻟﯿﭻ اﺳﺘﻔﺎده ﺷﺪ و ﻣﺪلﻫﺎي ﺳﯿﻨﺘﯿﮑﯽ ﺷﺒﻪدرﺟﻪاول و ﺷﺒﻪدرﺟﻪدوم ﺟﻬﺖ ﺗﻮﺻﯿﻒ ﺳﯿﻨﺘﯿﮏ ﺟﺬب ﺑﻪ ﮐﺎر ﺑﺮده ﺷﺪﻧﺪ. ﯾﺎﻓﺘﻪﻫﺎ: pH ﺑﻬﯿﻨﻪ ﺟﺬب روي ﺗﻮﺳﻂ ﻫﺮ دو ﺑﯿﻮﭼﺎر، pH 5 ﺑﻮد. ﺑﺎ اﻓﺰاﯾﺶ زﻣﺎن ﺗﻤﺎس، ﺑﺎزده ﺟﺬب روي ﺗﻮﺳﻂ دو ﺟﺎذب اﻓﺰاﯾﺶ ﯾﺎﻓﺖ و در زﻣﺎن ﺑﯿﺴﺖوﭼﻬﺎر ﺳﺎﻋﺖ ﺑﻪ ﺣﺎﻟﺖ ﺗﻌﺎدل رﺳﯿﺪ. ﺑﺎ اﻓﺰاﯾﺶ ﺳﻄﺢ دو ﺟﺎذب ﺗﺎ 20 ﮔﺮم در ﻟﯿﺘﺮ )0/8 ﮔﺮم( درﺻﺪ ﺣﺬف روي از ﻣﺤﻠﻮل اﻓﺰاﯾﺶ ﯾﺎﻓﺖ درﺣﺎﻟﯽﮐﻪ ﺳﻄﻮح ﺑﺎﻻﺗﺮ ﺳﺒﺐ ﮐﺎﻫﺶ ﮐﺎراﯾﯽ ﺟﺬب ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻣﺪل ﻻﻧﮕﻤﻮﯾﺮ ﻧﺴﺒﺖ ﺑﻪ ﻣﺪل ﻓﺮوﻧﺪﻟﯿﭻ ﺑﺮازش ﺑﻬﺘﺮي را ﺑﺮ دادهﻫﺎي ﺟﺬب روي ﻧﺸﺎن داد. ﺑﺮ اﯾﻦ اﺳﺎس، ﻇﺮﻓﯿﺖ ﺟﺬب روي ﺗﻮﺳﻂ ﺑﯿﻮﭼﺎر ﮐﺎهذرت )9/60 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮔﺮم( از ﺑﯿﻮﭼﺎر ﮐﺎه ﮔﻨﺪم )6/77 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮔﺮم( ﺑﯿﺶﺗﺮ ﺑﻮد. دادهﻫﺎي ﺳﯿﻨﺘﯿﮑﯽ ﺟﺬب، ﺗﻮﺳﻂ ﻣﺪل ﺷﺒﻪ درﺟﻪ دوم ﻧﺴﺒﺖ ﺑﻪ ﻣﺪل ﺷﺒﻪ درﺟﻪ اول ﺑﻬﺘﺮ ﺗﻮﺻﯿﻒ ﺷﺪﻧﺪ، ﺑﻨﺎﺑﺮاﯾﻦ ﺑﻪ ﻧﻈﺮ ﻣﯽرﺳﺪ ﮐﻪ روﻧﺪ ﻏﺎﻟﺐ ﺟﺬب روي ﺗﻮﺳﻂ ﺑﯿﻮﭼﺎر از ﻧﻮع ﺟﺬب ﺷﯿﻤﯿﺎﯾﯽ ﺑﺎﺷﺪ. ﺑﺤﺚ و ﻧﺘﯿﺠﻪﮔﯿﺮي: ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺑﯿﻮﭼﺎرﻫﺎي ﻣﻮرد اﺳﺘﻔﺎده در اﯾﻦ آزﻣﺎﯾﺶ ﻣﯽﺗﻮاﻧﻨﺪ ﺑﻪ ﻋﻨﻮان ﯾﮏ ﺟﺎذب ﻣﻮﺛﺮ، ارزان ﻗﯿﻤﺖ و دردﺳﺘﺮس ﺟﻬﺖ ﺣﺬف روي از ﻣﺤﻠﻮلﻫﺎي آﺑﯽ اﺳﺘﻔﺎده ﺷﻮﻧﺪ.

Introduction: In recent years, use of bio char as bio sorbent for pollution control of aqueous solutions containing heavy metals, has been considered by researchers. In the present study, the efficiency of wheat straw bio char and corn straw bio char for the removal of Zinc from aqueous solutions had been investigated under the influence of various factors such as pH, contact time, adsorbent dose and adsorbent concentration. Material and Methods: Langmuir and Freundlich models were used to describe the adsorption isotherm and Pseudo-first order and pseudo-second order kinetic models were applied for description of adsorption kinetics. Results: The optimum pH for Zn adsorption was found to be 5 by two bio chars. With increasing contact time, Zn adsorption efficiency was increased by two adsorbents and at 24 hours reached to equilibrium. The increase of bio char dosage until 20 g.L-1, the percentage of Zn removal in solutions was enhanced by tow adsorbents; however, the upper dosage of adsorbent caused a decrease in removal efficiency. The results indicate that the Langmuir model better fits on adsorption data than Freundlich model. Accordingly, Zn adsorption capacity by corn straw bio char (9.60 mg. g-1) was higher than the wheat straw bio char (6.77 mg.g-1). The kinetic data were better represented by the pseudo-second-order than the pseudo-first-order kinetic model, so it seems that the dominant process of Zn adsorption to be a chemisorption. Conclusion: The results showed that the bio chars which used in this experiment can be applied as a low-cost, effective and available adsorbent for removal of Zn from aqueous solutions.