Photocatalytic Decolourization and Degradation of C. I. Basic Blue 41 Using TiO₂Nanoparticles

The nanophotocatalytic process using semiconducting oxides with a nanostructure is one of the technologies used for the destructive oxidation of organic compounds such as dyes. The photocatalytic oxidation of a textile dye—C. I. Basic Blue 41 (BB41) in aqueous solution was assessed by UV ray irradiation in the presence of TiO2 nanoparticles. The effect of initial dye concentration, pH and TiO2 loading were investigated and the optimized conditions for maximum amount of degradation were determined. Analysis of the kinetics showed pseudo-first-order model. The mineralization of the dye was reported by measuring the initial and final chemical oxygen demand of the solution that was irradiated under optimized conditions.

Decolourization and Mineralization of Aqueous Solution Containing C. I. Basic Blue 66 in the Presence of Titanium Dioxide

Heterogeneous photocatalysis is an advanced oxidation process (AOP), which can be successfully used to oxidize many organic pollutants present in aqueous systems. This research studied the photocatalytic degradation of C. I. Basic Blue 66 (BB 66) in the presence of TiO2 P-25 Degussa as a photocatalyst. The influence of various parameters, such as mass of catalyst, initial concentration of dye and pH on the degradation process was examined. The degradation of the dye followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model and decolourization was achieved within 80 min of light exposure. The mineralization of organic carbon was also evaluated by measuring the dissolved organic carbon (DOC) of the dye solutions.

The Effect of Curative Concentration on Thermal and Mechanical Properties of Flexible Epoxy Coated Jute Fabric Reinforced Polyamide 6 Composites

Many researchers have shown interest in the reinforcement of commodity thermoplastic with natural fibers. However, the drawback of natural fibers is their low thermal processing temperatures, that border around 200℃. In this investigation, we tried to improve the thermal stability of natural fibers with the use of flexible epoxy surface coating that could facilitate processing with engineering thermoplastics. Jute fabric and Polyamide 6 (PA6) composites were prepared by compression molding. The thermal decomposition characteristics of the jute fabric were evaluated by using thermo gravimetric analysis (TGA). Mechanical analysis was conducted to evaluate tensile test and three point bending test of composite. It was found that thermal degradation resistance of jute fabric was improved by coating with flexible epoxy resin. Moreover, the flexural modulus improved with increasing curative concentration. The interfacial interaction between the epoxy and PA6 was clearly indicated by the photo micrographs of the polished cross sections of the coated and uncoated jute fabric/PA6 composites.

Synthesis of Some Azo Disperse Dyes from 1-Substituted 2-Hydroxy-6-pyridone Derivatives and Their Colour Assessment on Polyester Fabric

The synthesis of a series of 3-(p-substituted phenylazo)-6-pyridone dyes which is suitable for the dyeing of polyester fabrics, is described. Visible absorption spectra of the dyes were examined in various solvents and the compounds in solution exhibited hydrazone-common anion equilibrium. The electronic absorption spectra cover a λmax range of 404 - 464 nm in DMF at uniformly high absorption intensity between 5.33 × 104 - 8.55 × 104 lmol–1cm–1 and gave bright intense hues of yellow to orange on polyester fabrics. The colour parameters of the dyed fabrics were measured and the dyes have excellent exhaustion between 72% - 79% for polyester fabrics, more intense and of very good fastness properties on polyester fabrics. The remarkable degree of levelness and brightness after washing is indicative of good penetration and excellent affinity of these dyes for the polyester fabric.

Synthesis and Characterization of Nitrosonaphthol Dyes Based on 1-Naphthol and Their Dyeing Properties on Tanned Leather

Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exhaustion was better on chrome tanned leather than on vegetable tanned leather. This may be attributed to the chelating effect of chrome on leather and the higher temperature of dyeing the chrome tanned leather compared with the vegetable tanned leather. The fastness properties of the dyes of washing ranging from (3 - 5), perspiration on acid (4 - 5), alkaline (4 - 5) and light (4 - 7) were impressive on both vegetable and chrome tanned leather respectively.

The Effect of Epoxy Concentration and Fibre Loading on the Mechanical Properties of ABS/Epoxy-Coated Kenaf Fibre Composites

In this work, thermosetting resin, epoxy and fibre loading were used in optimizing the strength at which ABS/epoxy coated kenaf fibre (EKF) composites would perform apparently during mechanical stress. Kenaf bast fibres were resin coated before incorporated into engineering thermoplastic ABS at its processing temperature (230&degC), cured in-situ at internal mixer and later compression moulded at 210&degC under 65 kg/cm2pressure. The results showed the optimum level of tensile strength with thermoset and fibre loading as well as increase in strong interfacial bonding while the hardness values increased with increasing thermosetting and fibre contents. Both the tensile and flexural modulus apparently increased as the fibre contents increased.

The Synthesis of Diaminoanthraquinone Coloured Cross Linked Epoxy Resins and Their Application in Paint and Selected Polymers

Novel polymeric pigments were synthesized in xylene by cross linked epoxy resin with 1,4 and 1,5-diaminoanthraquinones, by varying weight fractions from 5% to 20% of the diaminoanthraquinone derivatives. FTIR, UV and solubility tests were carried out. The pigments were then used to colour PLA, PMMA, PE and also in emulsion paints using polyvinyl alcohol as binder. Their light fastness, surface drying time and surface hardening time were assessed. It was found that λmax of the 1,4-diaminoanthraquinone shifted towards longer wavelength after the cross linkage, in contrast to the 1,5-diaminoanthraquinone which suffered a blue shift. However in all the cases, the λmax was not affected by the weight fractions of the anthraquinones, but the absorptivity coefficients was significantly increased as the weight fractions of the anthraquinones increased. The light fastness properties of the coloured plastics varied from 4 to 7, indicating a trend of increase with the weight fractions of the anthraquinones. Similar observations were seen with the emulsion paints produced. In all the cases, the 1,4-diaminoanthraqunione produced better result.

Synthesis and Characterisation of Colorants Derived from 1,4-Diamino Anthraquinone Polyamides

In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.

Material Flow Analysis of Electronic Wastes (e-Wastes) in Lagos, Nigeria

The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requires reliable estimates of e-waste generation in the present as well as future times. In this study, a material flow model for the analysis of e-waste generation from computer equipments inNigeriahas been developed. Data used to develop the model are the sales data from major distributors of electronics, usage time of computer equipments and transfer coefficients of the electronics from one stage to another. The analysis of individual flows of computer from the material flow model showed that the fate of obsolete computer equipments were storage (41%), reuse (35%) and direct disposal (24%). The projections of the flows for a period of 15 years also indicated that storage and reuse of computer equipments would be preferred over direct disposal;and computer equipments would continue to remain in either storage, re-use or gradually disposed off for about 11 years after its inflow. This delay or staggering disposal is of advantage as it would reduce the amount of e-waste disposed yearly and also afford the country some time to make plans to accommodate and manage the e-wastes generated more efficiently.