James T. Guthrie

The removal of colour from textile wastewater using whole bacterial cells: a review

Abstract The delivery of colour in the form of dyes onto textile fibres is not an efficient process. The degree of efficiency varies, depending on the method of delivery. As a result, most of the wastewater produced by the textile industry is coloured. It is likely that coloured wastewater was a feature of the first practices of textile dyeing. However, treatment to remove this colour was not considered until the early natural dyestuffs were replaced by synthetic dyes, and the persistence of such synthetic dyes in the environment was recognised (Willmott NJ. The use of bacteria–polymer composites for the removal of colour from reactive dye effluents. PhD thesis, UK: University of Leeds; 1997.). Colour pollution in aquatic environments is an escalating problem, despite the fact that there has been substantial research into the modification of the dyeing process to improve the level of affinity/fixation of the dyestuffs onto the substrate. The recalcitrant nature of modern synthetic dyes has led to the imposition of strict environmental regulations. The need for a cost-effective process to remove the colour from wastewater produced by the textile industry has been recognised (Willmott NJ, Guthrie JT, Nelson G. The biotechnology approach to colour removal from textile effluent. JSDC 1998;114(February):38–41.). Several strategies have been investigated. However, the review presented here concerns the use of whole bacterial cells for the reduction of water-soluble dyes present in textile dyeing wastewater.

Structural order in alkali-degraded PAN as seen in studies of low-temperature thermal conductivity

Abstract The thermal conductivity, κ, of polyacrylonitrile (PAN), subjected to varying degrees of degradation, has been measured in the temperature range 2–100 K as a means of studying the structural order of the samples. Although, at higher temperatures, the variation in κ throughout the range of specimens is only ∼ 30%, at 2 K there is an order of magnitude increase in conductivity between the undegraded and most highly degraded samples. Such a change is indicative of a pronounced decrease in crystallinity, and this interpretation is supported by estimates of crystallinity as seen through X-ray analysis.

Synthesis of natural–synthetic hybrid materials from cellulose via the RAFT process

The synthesis and characterization of a novel natural-synthetic hybrid material based on cellulose is reported. The reversible addition-fragmentation chain-transfer (RAFT) process was used to graft poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) onto a cellulosic substrate. The weight ratio was increased with an increase in monomer concentration, polymerization time and degree of polymerization (DP). We found that the addition of free chain-transfer agent has a pronounced effect on the weight ratio, chain length of grafted polymer, monomer conversion and homopolymer formation in solution. The cellulose-graft-poly(2-(dimethylamino)ethyl methacrylate) copolymers were characterized by gravimetry, elemental analysis, attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analysis and atomic force microscopy. The dithioester end-group present at the chain end of PDMAEMA was removed via aminolysis. The livingness of the process was utilized to block-copolymerize styrene from the grafted PDMAEMA chains. The hydrophilic/hydrophobic properties of the novel cellulose-g-(PDMAEMA-b-polystyrene) material were illustrated by contact-angle measurements.

Characterisation of the surface Lewis acid–base properties of poly(butylene terephthalate) by inverse gas chromatography

The surface of poly(butylene terephthalate) (PBT) was analysed by means of inverse gas chromatography (IGC). The specific component of the adsorption of polar probes on the surface of poly(butylene terephthalate) was found to be endothermic, and the change in the entropy of the system, positive, which is not a common case in IGC. An interpretation is given, based on the contribution of cleavage of hydrogen bonds in the PBT and formation of hydrogen bonds between the probe-molecules and the polymer. The surface Lewis acidity and basicity constants, Ka and Kb, respectively, were determined and found to correlate well with an analysis of the repeating unit and end-groups in this polymer.

Colour removal from aqueous solutions of metal-complex azo dyes using bacterial cells of Shewanella strain J18 143.

The decoloration treatment of textile dye effluents through biodegradation, using bacterial cells, has been studied as a possible means of solving some of the problems that are associated with the pollution of water sources by colorants. In this paper, the use of whole bacterial cells of Shewanella J18 143 for the reduction of aqueous solutions of selected mono-azo, metal-complex dyes, namely Irgalan Grey GLN, Irgalan Black RBLN and Irgalan Blue 3GL, was investigated. The effects of temperature, pH and dye concentration on colour removal were also investigated and shown to be important. The operative conditions for the removal of colour were 30 degrees C, at pH 6.8, with a final dye concentration of 0.12 g/L in the colour reduction system. This study provides an extension to the application of Shewanella strain J18 143 bacterial cells in the decoloration of textile wastewaters.

Characterisation of the surface Lewis acid-base properties of the components of pigmented, impact-modified, bisphenol A polycarbonate-poly(butylene terephthalate) blends by inverse gas chromatography-phase separation and phase preferences.

Inverse gas chromatography was used to study the surface Lewis acid-base properties of the major components of pigmented, impact-modified, polycarbonate-poly(butylene terephthalate) blends. An investigation of the Lewis acid-base interactions in these polymeric systems has been carried out, based on the values determined for the surface Lewis acidity constant (Ka), surface Lewis basicity constant (Kb) and on the chemical and physical structure of the materials involved. This analysis provided the rationale for an interpretation of the phase separation and the phase preference that exist in these polymer blends, and of the consequences to their physical and mechanical properties.

Computational simulation of the printing of Newtonian liquid from a trapezoidal cavity

A Lagrangian finite element algorithm is described for solving two‐dimensional, time‐dependent free surface fluid flows such as those that occur in industrial printing processes. The algorithm is applied using a problem specific structured meshing strategy, implemented with periodic remeshing to control element distortion. The method is benchmarked on the problem of a stretching filament of viscous liquid, which clearly demonstrates the applicability of the approach to flows involving substantial free surface deformation. The model printing problem of the transfer of Newtonian liquid from an upturned trapezoidal trench (3‐D cavity with a large transverse aspect ratio) to a horizontal substrate, which is pulled perpendicularly downwards from the cavity, is solved computationally using the Lagrangian scheme. The idealized 2‐D liquid motion is tracked from start‐up to the point where a thin sheet forms – connecting the liquid remaining in the cavity to a “sessile” drop on the moving substrate. The effect of varying substrate separation speed is briefly discussed and predictions are made for approximate drop volumes and “limiting” domain lengths.

Characterisation of the surface of a cellulosic multi-purpose office paper by inverse gas chromatography

The surface of multi-purpose cellulosic office paper has been analysed by inverse gas chromatography (IGC). The parameters determined were the dispersive component of the surface free energy, the enthalpy of adsorption and the entropy of adsorption of polar and apolar probes, the Lewis acidity constant, Ka, and the Lewis basicity constant, Kb. It can be concluded that the dispersive component of the surface free energy, γsd decreases with temperature, in the range 50–90°C. The temperature coefficient of γsd, dγsd/dT, is −0.35 mJm −2K−1. The values of Ka and Kb were determined to be 0.11±0.011 and 0.94±0.211, respectively. The predominant surface basicity agrees with expectation, bearing in mind the presence of calcium carbonate, and of a styrene-acrylic copolymer, in the surface sizing formulation. It is thought that during the drying stages following the surface sizing treatment, the starch used as the binder migrates to the interior of the surface sizing layer and then to the paper bulk itself. This migration contributes to a decrease in the hydrophilicity of the surface, and also results in the surface showing only slight Lewis.

Polymer blends: the PC–PBT case

An example of commercially important binary polymer blends is that of PC–PBT composites. The current knowledge of the physical, mechanical and chemical properties of these blends is reviewed and updated in the light of interpretations based on Lewis acid–base intermolecular interactions, as quantified by inverse gas chromatography, carried out under infinite dilution conditions.

UV-cured natural polymer-based membrane for biosensor application

Chitosan, a natural product, is inherently biodegradable, biocompatible, and nontoxic. These properties make chitosan ideal for inclusion in matrices designed for use in enzyme immobilization for clinical analysis. This study demonstrates the feasibility of using chitosan in electrochemical biosensor fabrication. The enzyme sulfite oxidase (SOX) was covalently immobilized onto the matrix of chitosan–poly(hydroxyethyl methacrylate) (chitosan–pHEMA), a natural/synthetic polymer hybrid obtainable via UV curing. p-Benzoquinone, which served as an electron transfer mediator, was coupled onto the polymer network for activation of the chitosan–pHEMA copolymer, after completion of the photo-induced polymerization reaction. The biological activity of the immobilized SOX and the electroactivity of the coupled p-benzoquinone were investigated.