Authors:N. Khalid, A. Rahman, S. Ahmad, A. Toheed, and J. Ahmed
Rice husk, an agricultural waste product, was studied as a potential decontaminant for chromium in the effluents of leather
tanning industries. Physico-chemical parameters such as selection of appropriate electrolyte, shaking time, concentration
of adsorbent and adsorbate were studied to optimize the best conditions in which this material can be utilized on commercial
scale for the decontamination of effluents. The radiotracer technique was used to determine the distribution of chromium.
In certain cases atomic absorption spectrophotometry was also employed. Maximum adsorption was observed at 0.01 mol·dm−3 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 3.0 g of adsorbent for 2.73·10−3 mol·dm−3 chromium concentration in five minutes equilibration time. Studies show that the adsorption decreases with the increase in
the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 2.73·10−3 to 2.73·10−2 mol·dm−3 chromium concentration. The characteristic Freundlich constants, i.e., 1/n=0.86±0.06 andA=2.35±0.06 mmol·g−1 have been computed for the sorption system. Thermodynamic parameters, i.e., ΔG0, ΔS0 and ΔH0 have also been calculated for the system. Application of the method to a test case of a medium size industry showed that
21 kg of rice husk was sufficient to maintain the NEQS limits of chromium for industrial effluents.
Authors:S. Waheed, N. Siddique, M. Arif, I. Fatima, N. Khalid, S. Rahman, M. Daud, and M. Wasim
This paper presents the results of the proficiency test exercise conducted in Pakistan for the determination of trace elements
in mushroom reference material. Thirteen laboratories from different organizations of the country submitted trace elemental
data on Al, As, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hg, K, Li, Mg, Mn, Na, P, Pb, Rb Sc, Si, Sm, Sr, Th, Zn. Results for
Al, As, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Na, Rb Sc, and Zn, in the mushroom material were reported by two or
more participating laboratories and could be subjected to statistical evaluation. The original data of these trace elements
was subjected to a computer program “Histo Version 2.1” provided by IAEA. The four outlier tests, i.e., Dixon, Grubbs, skewness
and kurtosis were applied to the data sets. Consensus (overall) mean values, absolute standard deviation, relative standard
deviation, standard error, median and range of values for these elements have been reported at a significance level of 0.05.
Authors:K. Habib, M. Arshad, A. Bano, and A. N. Khalid
Two lichen species, Variospora kudratovii and Zeroviella laxa, and a lichenicolous species, Polycoccum clauderouxii are reported for the first time from Pakistan and represent first generic records as well. Detailed macro- and micromorphological descriptions and spot test results are provided along with ITS-based molecular phylogenetic analysis.