The Speciation of Environmentally Significant Metals from Pulp and Paper Mill Effluent with Selected Inorganic Ligands and their Impact on Water Quality of River Nzoia, Kenya

  • James Amayi Department of Chemistry and Biochemistry, School of Science, University of Eldoret, P.O. Box 1125, Eldoret, Kenya
  • Titus M. Muthoka Department of Chemistry and Biochemistry, School of Science, University of Eldoret, P.O. Box 1125, Eldoret, Kenya.
  • Kituyi Lusweti Department of Chemistry and Biochemistry, School of Science, University of Eldoret, P.O. Box 1125, Eldoret, Kenya.
  • Charles Omindo Department of Chemistry, School of Pure and Applied Sciences, Kenyatta University, P. O. Box 43844, Nairobi, Kenya
  • Sherry Oluchina University of Eldoret, P.O Box 1125, Eldoret, Kenya.

##article.abstract##

The effluents from Webuye paper mill were analysed chemically using Atomic absorption spectroscopy to obtain the stoichiometric concentrations of the major anions and cations. However, this does not indicate how the components are distributed amongst possible species. pH was measured with pH meter previously calibrated with pH buffer, alkalinity was determined by titration using phenolphthalein indicator and 0.010 M HCl, chloride was analyzed by titration using potassium chromate indicator and standardized 0.014 N mercuric (II) nitrate solution. A pH dependent model for the speciation of divalent Pb and Cu ions downstream was constructed with corrected IUPAC stability constants using SPECIES computer program. Modelling results showed that inorganic speciation behaviour was of three types; (a) Pb and Cu were dominated by carbonato- complexes at pH 8.0, PbCO3(aq) having 66.06% and CuCO3(aq) 90.45% abundance. Bicarbonato complexes could only form to significant levels at high [HCO3-]T and high ionic strength. (b) Chloro-complexes of Pb and Cu that formed were PbCl+, PbCl2(aq), PbCl22-, CuCl+ and CuCl2(aq). All these complexes were weak and could best be studied in media of high [Cl-]T, high [Cl-]T : [Metal]T ratios and high ionic strength. The fraction of free aquo ions (Pb2+ and Cu2+) dominated speciation with increase in [Cl-] and pH. (c) Hydroxo- complexes of Pb were dominated by carbonato- complexes over a wide range of solution conditions.

References

APHA-AWWA-WPCF (1985).Standard Methods for the Examination of Water and Wastewater, ALPHA-AWWA-WPCF, Washington DC.

Ferri , D., & Branica, M. (1989). Studies on Metal Carbonate Equilibria. 12. Zinc(II) Carbonate Complexes in Acid Solutions (13th ed.). Scandinavica, Scandinavia: Acta Chemica Scandinavica.

Grenthe I.al., (1992).Chemical Thermodynamic of Uranium, Elsevier, Amsterdam.

Morel, F. M., & Hering J. G. (1993).Principles and Applications of aquatic Chemistry. John Wiley, New York.

Perera, W. N., Hefter G., &Sipos P. M. (2001)."An investigation of the lead(II)-hydroxide system", INORG CHEM, 40(16), 2001, pp. 3974-3978

Pettit L. D., & Powell K. J. (2005). SC-Database, IUPAC Stability Constants Database. Release 5, IUPAC, Academic Software, Otley, UK.

Pettit, L.,& Pettit, G. (2009). A more realistic approach to speciation using the IUPAC Stability Constants Database.

Powell, K. J. (2007). Guidelines for potentiometric measurements in suspensions Part B. Guidelines for practical pH measurements in soil suspensions (IUPAC Recommendations 2006).Pure and Applied Chemistry, 79(1), 81-86. doi:10.1351/pac200779010081

Powell, L., & Pettit, G. (2009).A more realistic approach to speciation using the IUPAC Stability Constants Database.

Trivedi, R. K., & Goyal, P. K. (1986).Chemical and Biological Methods for Water pollution Studies, Environmental publications, Karad.

UNEP, (1992).Saving Our Planet Challenges and Hopes.United Nations Environment Programme, Nairobi. Pp 1-8.
##submissions.published##
2018-09-14
##issue.issue##
##issue.vol## 1 ##issue.no## 4 (2014)
##section.section##
Articles