University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Waste

Classification: Waste -> solid

Citations 4

"Selective Determination Of Gas Dialysable Components In Complex Sample Solutions Using Triangle Programmed Coulometric Titration In Continuous-flow Systems"
Anal. Chim. Acta 1996 Volume 324, Issue 2-3 Pages 115-123
M. Becker, B. Fuhrmann and U. Spohn*

Abstract: A method is described for determining ammonium/NH3 and sulfide/hydrogen sulfide in leachate from a municipal waste land-fill site. Sample (0.1 ml/min) was merged with a conditioning stream (0.1 ml/min) of 0.1 M NaOH (for ammonium/NH3) or 0.1 M HCl (for sulfide/hydrogen sulfide) and the mixture was propelled through the donor channel of a dialysis cell. The generated NH3 and H2S were adsorbed into acceptor streams (0.2 ml/min) of 0.1 M KBr/0.1 M sodium borate of pH 8.3 or 0.1 M KBr/0.1 M NaHCO3, respectively, and titrated with electrogenerated hypobromite produced at Pt electrodes by the oxidation of bromide. After the oxidations of NH3 and H2S, the remaining bromine was detected amperometrically at a Pt electrode (0.18 V) and the remaining hypobromite was detected by chemiluminescence via its reaction with 20 µM-luminol (2 ml/min). For ammonium/NH3, the linear ranges were 10 µM-10 mM with amperometric detection and 1 µM-0.5 mM with chemiluminescence detection and RSD (n = 6) were 3%. The linear range for sulfide/H2S was 0.2 µM-0.5 mM with chemiluminescence detection and the RSD (n = 6) was 4%. The sampling frequency was 30 samples/h.
Ammonium Sulfide Coulometry Amperometry Electrode Chemiluminescence Titrations Gas diffusion Membrane Electrochemical reagent generation Dialysis

"Using FIMS To Determine Mercury Content In Sewage Sludge, Sediment And Soil Samples"
J. Autom. Methods Manag. Chem. 1996 Volume 18, Issue 6 Pages 221-223
TIEZHENG GUO and JÖRN BAASNER

Abstract: Sewage sludge (0.01 g) spiked with Hg was weighed into a digestion flask, moistened with a few drops of water and 21 mL HCl and 7 mL HNO3 were added. Digestion was carried out in accordance with DIN 38414, Part 12. The cooled solution was diluted to 100 mL with water. A portion (100 µL) of 0.5% K2Cr2O7 in HNO3/H2O (1:1) was added to 1 mL supernatant and the mixture was diluted to 10 mL. Samples were reduced with 1.5% SnCl2 in 1% HCl prior to Flow injection Mercury Systems (FIMS) analysis. Recoveries of Hg in spiked sewage sludge were 96-100% and analyzes of standard reference samples were in agreement with certified values. RSD (n = 3) were ~2% for 10 µg/l of Hg. Results obtained by FIMS were in agreement with values obtained by FIA generation of Hg vapor and AAS.
Mercury Spectrophotometry Sample preparation FIMS Volatile generation Method comparison Reference material Volatile generation

"Flow-injection Analysis (FIA)-cold Vapour (CV) AAS Determination Of Mercury In Waste Samples"
Lihua Jianyan, Huaxue Fence 1998 Volume 34, Issue 10 Pages 449-450
Ma Hongbing, Liu Huijun, Li Junxiang

Abstract: A method for the determination of Hg in garbage samples by the combination of FIA hydride generation and atomic absorption spectrometry was presented. The sample was digested with V2O5-HNO3 solution at 140°C, and then H2SO4 solution at 180°C, and determined by FIA-CV AAS with NaBH4 as reducing agent. The effects of the concentration. and flow rate of the reaction medium, the length of the reaction coil, and the coexisting ions on the determination are discussed. The characteristic concentration. was 0.45 µg/L, the detection limit 0.06 µg/L, the relative standard deviation 0.75%, and the recovery 99- 102%. The method had the advantages of high accuracy and precision, simple and rapid operation, and low consumption of chemical reagents.
Mercury Sample preparation Spectrophotometry Optimization

"Experiences With Automatic N And P Measurements Of An Activated Sludge Process In A Research Environment"
Water Sci. Technol. 1996 Volume 33, Issue 1 Pages 165-173
S. Isaacs and H. Temmink

Abstract: Some of the advantages of on-line automatic measurement of ammonia, nitrate and phosphate for studying activated sludge systems are pointed out with the help of examples of batch experiments. Sample taking is performed by cross-flow filtration and measurement of all three analytes is performed by Flow Injection Analysis (FIA). Two batch set-ups are described. In the first, one of the two 800 l nitrifying/denitrifying tanks of a pilot-scale alternating process is employed as batch reactor, which has the advantage of a high measurement frequency and little preparatory and clean-up effort. The second consists of four 5 l jars connected to the FIA system and allows on-line measurement of ammonia, nitrate and phosphate while performing batch reactions in parallel. Each of the four examples described was designed to study a particular aspect pertaining to Enhanced Biological Phosphate Removal (EBPR): the effect of acetate addition on aerobic P-uptake; the recovery of aerobic P-uptake after a disturbance; the interaction between denitrification and P-release when acetate is added at various rates; and the effect of stored PHB levels on denitrification by phosphate accumulating organisms.
Nitrogen Filtration Automation