Coal Ash as Pollutant and Adsorbent for Heavy
Coal Ash as Pollutant and Adsorbent for Heavy Metal Ions in Water Streams Majlinda N. Daci, 1 Nexhat M. Daci, 1 Lulzim Zeneli, 2 Salih T. Gashi, 1 Dafina Hoxha 1 1 Chemistry Department, University of Prishtina, Republic of Kosovo Institute, Faculty of Medicine, Republic of Kosovo 2 Biochemistry
“We are living in a false economy where price of goods and services does not include the cost of waste and pollution” Lyn Landers, Founder and Director of Zero Waste America • Coal is the most abundant Natural Energy Resource and comprises 61% of the world energy reserves, in comparison with 15% oil, 15% natural gas and 9% oil shale. • Kosova is one of the biggest owners of the coal energy resource in Balkans, and Kosova lignite type coal is the biggest value of mineral resource. • For that reason, Coal and other energy sources, are of major interest, because they contain elements that have undesirable physiological effects of plant, animal and human life, such as Hg, Be, Se, As, Cd, Pb, F, etc. • The inorganic material in coals, which appear in environment as bottom and fly ash, is of special interest, because much of it occurs organically bound to the coal substance as cations associated with carboxyl groups, or forms some types of organometalic compounds or stable organic complexes (metal-porphyrines, metal-carbonyls, metalocenes, arene carbonyls, metal-alkyls and metal-chelates). • Since several last decade of XX century and the first decade of this century almost the only energy resource for electricity in Kosova was and still is lignite coal. The emissions in Kosova Environment each year are as follows: 2 -3 milion tons of ashes and 102 000 tons of sulphur.
The content of heavy metals in the amount of ash, that enter Kosova Environment each year. Cu 314 t Ni 351 t Co 3. 8 t Ti 492 t Mn 191. 2 t Mo 2. 1 t Cd 1. 08 t As 11. 3 t Pb 3. 24 t Be 2. 16 t V 0. 48 t
To evaluate Environmental impacts from using coal in thermo power plants in Kosova, our research for many years was oriented to: • Structural determination of organic coal substance (its carbon matrix and oxygen functional groups as –COOH; -C=O; and -SH groups). • Heavy metal ions linked to those groups. • Transport of heavy metal ions in water streams ( for example to Ohrid lake and fish organs). • Fly ash as adsorbent for heavy metal ions and organic pollutants. • Interference and effects of heavy metal ions to biochemistry blood parameters. 1. L. Zeneli, N. Daci, M. Daci-Ajvazi, H. Paçarizi, //Effects of pollution on lead and cadmium concentration and correlation with biochemical parameters in blood of human population nearby Kosovo thermo power plants// American Journal of Biochemistry and Biotechnology, 4 (3): 273 -276, 2008. 2. Lulzim Zeneli, Nexhat Daci, Hidajet Paçarizi, Majlinda Daci-Ajvazi, //Interaction between cadmium and calcium in human blood at smokers// American Journal of Pharmacology and Toxicology 5(1): 48 -51, 2010. 3. (Suzana Zhuta “ Environmental chemical pollutants of lake Ohrid” Ph. D thesis)
Physical-chemical characteristics of fly ash Fly ash wt% Constituents Fly ashes from Kosova thermo power plants were examined as adsorbent for heavy metal cations. Loss on ignition 2. 20 Si. O 2 26. 75 Al 2 O 3 4. 00 Fe 2 O 3 10. 77 Ca. O 41. 48 Mg. O 4. 36 Na 2 O 1. 42 K 2 O 0. 16 Ti. O 2 0. 50
Adsorption of heavy metals with fly ash Sorbent Fly Ash Metal ions Co*/mg/dm 3 Indiv. Total Cu Fe Mn 35. 21 69. 94 34. 98 140. 13 Cd Zn Pb 35. 34 34. 99 47. 54 117. 87 Cd Zn Pb 35. 34 34. 99 47. 54 140. 13 117. 87 p. H t/mi n Ce*/mg/dm 3 Indiv. Total 10 0 15 0 4. 60 30 0 15 0 5. 90 10 0. 04 2. 24 20. 48 18. 20 30 0 1. 74 19. 69 17. 95 4. 60 5. 90 Co – initial concentration; Ce – final concentration 15 15 p. H % removal Individ. total 11. 80 100 78. 55 92. 85 100 11. 90 100 78. 55 92. 85 100 11. 80 99. 89 93. 60 85. 07 61. 72 11. 90 100 95. 03 85. 75 62. 24
Diagram of initial and final concentration of Cu, Fe, Mn, Cd, Zn and Pb, before and after treatment
According to chemical composition, in Kosova fly ash dominates alkaline components (Ca. O 41. 48% and Mg. O 4. 36%) toward acidic (Si. O 2 26. 75% and Al 2 O 3 4%), we estimated that this ash might be used also for treatment of acidic mine and metal industrial wastewaters. Characteristics of industrial water, p. H changes after treatment Elements (mg/dm 3) Industry Initial p. H Batteries 1. 12 Electrolysis Fertilizer Reaction time p. H after treatment Pb Zn Cu Cd 1 hour 10. 8 4 1. 6 0. 45 0. 02 2. 35 1 hour 12. 5 2. 2 300 1. 58 1. 25 1. 7 1 hour 5. 55 1. 5 11. 1 0. 25 0. 12
Removal of some elements from industrial water using fly ash as adsorbent Elements (mg/dm 3) before treatment after treatment Industry Pb Zn Cu Cd Pb Zn Cu d Batteries 4. 0 1. 6 0. 45 0. 02 0. 37 0. 03 0. 06 0. 07 Electrolysis 2. 2 300 1. 58 1. 25 5. 8 25. 75 0. 05 Fertilizer 1. 5 11. 1 0. 25 0. 12 0. 23 0. 07 0. 06
The same experimental procedure was used to asses sorbent properties of ash in treating the real systems, water stream of Sitnica river Adsorption of heavy metals with fly ash at river stream of Sitnica. Sorbent Fly Ash Metal ions Co* (mg/dm 3) Cu Fe Mn 0. 162 1. 055 0. 494 p. H 7. 6 t/min Ce* (mg/dm 3) 30 0. 038 0. 115 0 60 0. 106 0. 147 0. 011 p. H % removal 12. 07 76. 55 89. 1 100 12. 5 34. 57 86. 06 77. 74
Diagram of initial and final concentration of Cu, Fe and Mn before and after treatment for 30’ and 60’.
Conclusion Based on the results that were achieved during a period of time following conclusions can be summarized: 1. Kosova fly ash shows good sorption capacity toward heavy metal ions and other pollutants. 2. The sorption rates were very high. Over 90% of the total adsorption can be obtained in ten minutes of reaction time. 3. Contribution of fly ash in changing p. H values of studied acidic wastewater of Lead and Zinc industry, indicated that adsorption (as primary effect) might be accompanied by precipitation process.
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