K Van den Broeck

Low-temperature pyrolysis of CCA-treated wood waste : Chemical determination and statistical analysis of metal input and output ; mass balances

Low-temperature pyrolysis is proposed as an alternative method to dispose of CCA-treated wood waste. In the frame of a study aiming at optimising the pyrolysis of CCA-treated wood, an experimental facility has been built to examine the influence of important process parameters (pyrolysis temperature, residence time, heating rate, particle size, …) on the release of metals and on the resultant mass reduction. In order to perform a mass balance calculation for the total system, a method for metal analysis was developed. Two leaching procedures and one dissolution procedure were tested and compared with each other, resulting in an optimal procedure to bring the metals into solution: “the BSI method” to determine the total amount of Cr, Cu and As in the dried wood and “the Reflux method” to determine the total amount of Cr, Cu and As in the pyrolysis residue. These results illustrate that Cr is more strongly bound in the pyrolysis residue compared to the CCA-treated wood. The analytical technique used was ICP-MS and the analytical problems like interferences and matrix effects were solved by using the appropriate isotope, an internal standard and mathematical corrections. The resulting optimal technique for CCA-treated wood (“the BSI method”) was applied to wood samples with different particle sizes. A statistical analysis of the Cr, Cu and As content in the CCA-treated wood shows the heterogeneous character of CCA-treated wood samples. Heterogeneity becomes less important when using samples with a small range of particle sizes. The smaller wood particles have significantly higher metal concentrations than the larger particles. Realistic mass balances for the metals were obtained and showed that most of the Cr, Cu and As remained in the pyrolysis residue.

High glass transition chromophore functionalised poly(maleimide-styrene)s for second-order nonlinear optical applications

Nonlinear optical polymers with high glass transition temperatures were prepared by polymer analogous reaction of maleic anhydride copolymers, with aminoalkyl-functionalised azo- and stilbene chromophores. Glass transition temperatures from 178 to 228°C were obtained. Poled films of the polymers were characterised by second-harmonic generation and showed a nonlinear optical response that is stable at elevated temperatures.

Sustainable treatment of HF wastewaters from semiconductor industry with a fluidized bed reactor

Within the semiconductor industry, large volumes of hydrogen fluoride (HF) containing wastewaters need to be treated. This paper describes a technique that makes it possible to treat HF wastewater with virtually no waste production. A method based on crystallization of CaF/sub 2/ on sand particles in a fluidized bed reactor, with trade name Crystalactor, was assessed for the first time with real wastewater originating from a semiconductor prototyping line. Several process parameters were investigated such as influent fluoride concentration, calcium reagent excess, pH, single versus multiple calcium reagent dosing, etc. It can be concluded that the performance of the reactor is greatly dependent on the initial concentrations of calcium and fluoride at the bottom of the reactor (referred to as local saturation). The original hardware design was changed from a single reagent dosing to a multiple reagent dosing to prevent too high local supersaturation values of fluoride and calcium and thus obtain higher CaF/sub 2/ crystallization efficiencies. Fluoride loads up to 7 kg/m/sup 2//spl middot/h were still possible with multiple reagent dosing, compared to a maximum treatable load of 3.5 kg/m/sup 2//spl middot/h for single reagent dose. Additionally, an alternative post-treatment process based on replacement of calcite by fluorite in a granular calcite column is demonstrated.

Polymer materials for second-order non-linear optical applications

Non-linear optical (NLO) polyimides and poly(maleimide-styrene)s were prepared and characterized by second-harmonic generation. Poled films of the polymers showed up to 90% of remaining NLO response at elevated temperatures; this during prolonged time at 125 °C.

High glass transition temperature chromophore functionalised poly(phenylquinoxalines) for nonlinear optics

New chromophore functionalised second-order nonlinear optical (NLO) poly(phenylquinoxalines) were prepared by reaction of a bis(1,2-dicarbonyl)chromophore monomer and a tetraamine at room temperature. The heterocyclic polymers have high glass transition temperatures (>195 °C) and can therefore be excellent polymeric materials with high poling stabilities of the NLO effect.

ICP–MS, hydride generation-ICP–MS, and CZE for the study (analysis and speciation) of solidification/stabilisation of industrial waste containing arsenic

Abstract Different analytical methods were applied to analyse the leachates obtained from leach tests on S/S industrial waste containing arsenic and the treated percolate water from a landfill. Inductively coupled plasma–mass spectrometry (ICP–MS) was used to determine total As and other elements, hydride generation-ICP–MS for the determination of As(III) and capillary zone electrophoresis (CZE) for As(III) and As(V). Interferences and matrix effects were studied in detail and corrected for. For the leachates, no corrections were required, for treated percolate water with lower As concentrations, in the case of ICP–MS important corrections were necessary. Results for different types of leach tests (extraction, static and semi-dynamic) and for treated percolate waters are presented.

Electrocoagulation as a viable technique to treat (Cu-)CMP wastes

CMP has become a major process technology. As a result, high volumetric CMP waste streams containing suspended slurry particles and residues, polished from the wafer surface, are generated. This imposes severe demands on the treatment of these effluent streams, since the presence of the high TSS-content and metals like Cu and W is considered as environmental hazardous. In the present study it is demonstrated that the simple technique of electrocoagulation (EC) is a viable alternative to treat (Cu-)CMP wastes. A wide range of silica and alumina-based slurries (and mixtures thereof) have been tested in a lab-scale setup. Electrocoagulation has been found to destabilize in a relatively short time these suspensions. As a result, a transparent supernatant is formed, besides a compact, low volume sludge residual, which can be readily removed by simple, classical filtration. Moreover, the Cu and W present in the waste are removed from the liquid phase with efficiencies >99%, resulting in final metal concentrations below 100 ppb, thus well below water discharge limits. Experiments were done with both simulated and real wastes, which exhibited basically the same behavior.

Polymers for second-order nonlinear optical applications

The aim of our investigation is the development of new polymeric materials with nonlinear optical properties which are comparable or even better than the existing organic salts such as LiNbO/sub 3/, KDP etc. Nonlinear optical (NLO) polymers which show large second-order NLO properties and which show long-term stability, low optical loss and good processibility to fabricate thin films and fibers are of considerable interest in the development of new materials used for frequency doubling applications and for their use in optical communication.

ICP-MS, Hydride Generation-ICP-MS, and CZE for the Study (Analysis and Speciation) of Solidification/Stabilisation of Industrial Waste containing Arsenic

Different analytical methods were applied to analyse the leachates obtained from leach tests on S/S industrial waste containing arsenic and the treated percolate water from a landfill. ICP-MS was used to determine total As and other elements, hydride generation-ICP-MS for the determination of As (III) and capillary zone electrophoresis (CZE) for As (III) and As (V). Interferences and matrix effects were studied in detail and corrected for. For the leachates, no correction, were required. for treated percolate water with lower As concentrations, in the case of ICP-MS (inductively coupled plasma-mass spectrometry) important corrections were necessary. Results for different types of leach tests (extraction. static and semi-dynamic) and for treated percolate waters are presented.