Polylactic acid/thermoplastic tapioca starch blend incorporated with selected essential oils for active food packaging

The environmental effect of petroleum-based polymers and the activity of food spoilage microorganisms made researchers work on alternative bioactive packaging materials. This work aimed at producing sustainable thermoplastic tapioca starch (TPTS) and its polylactic acid (PLA) blend with introduction of antimicrobial (AM) activity via incorporation of lemongrass (LG), lemon balm (LB) and pandan (PA) essential oils (EOs) on the films. The plasticising effect of glycerol and water and compatibilising effect of vinegar loadings on the properties of TPTS were tested. So also the impact of TPTS loading on the PLA/TPTS blend properties. Furthermore, the AM activity of TPTS incorporated with the EOs on E. coli, B. cereus and S. marcescens was evaluated by inhibitory zone; and packaging effect of PLA/TPTS films coated with the EOs on death rate of microorganisms inoculated on Bahulu cake was investigated. The TPTS was formed by tape casting method, while PLA/TPTS film by hot pressing. The results indicated an increase in crystallinity and elongation at break with increase in plasticiser loading in TPTS and percentage TPTS loading in PLA/TPTS blend; both were accompanied by a decrease in Tg and tensile strength. Continuous surface morphology was seen at high plasticiser loading in TPTS, while high TPTS loading manifested a phase separation in PLA/TPTS blend. The results show that 125 C processing temperature, 15 wt% glycerol, 45 wt% water and 3.5 wt% vinegar loading were optimum parameters for TPTS production. Whereas, 185C processing temperature and 25 wt% TPTS loading are optimum parameters for PLA/TPTS blend production. Citral was found as the common active compound among the EOs. LG and LB were active against all the tested microorganisms, while PA was very mild at higher concentration. For active TPTS and PLA/TPTS films activity, E. coli: LB˃LG˃PA; B. cereus: LG˃LB˃PA; S. marcescens: LB˃LG˃PA. The TPTS and PLA/TPTS active films produced have shown improved properties for food packaging and effective AM activity against the selected microorganisms

Effects of Acid Treatment on the SEM-EDX Characteristics of Kaolin Clay

Raw kaolin was refluxed by sulphuric acid in variable concentrations of 2 M, 4 M, 6 M and 8 M. The morphology and elemental compositions of the acid-leached kaolin were analyse by Field Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray analysis (EDX) respectively. The disintegration and leaching of Al3+ ions of the clay are determined by FESEM studies. The acid treatment increases the silicon content and decreases aluminium content as revealed by EDX analysis. The leaching of Al3+ ions increases with gradual increase in concentration of the acid. Therefore, kaolin reflux with acid at lower strength (2 M and 4 M) are more dispersed and more industrially useful than that which is treated at higher acid strength

Structural and morphological studies of polypropylene/kaolin nanocomposite

Nanocomposite of polypropylene (PP) was made by melt intercalation technique with nanokaolin. Kaolin particles were modified with urea by intercalation to produce nanokaolin. Structural and morphological analyses of polypropylene/kaolin nanocomposite was investigated by Fourier Transform Infrared (FT-IR) spectroscopy and Field Scanning Electron Microscopy (FESEM). The interaction of FT-IR confirms hydrogen bonds formed between urea molecules and the inner surface of kaolin layers. It also gives evidence that kaolin was dramatically delaminated into nano scale by intercalation activity. Whereas, FESEM shows kaolin particles were homogeneously dispersed into the PP matrix

Speciation of Potentially Toxic Metals from the Mine Impacted soils: A Case Study of Riruwai Mining Area, Kano State, Northern Nigeria

Mining and smelting sectors contribute significantly to global growth on a regional and local scale. However, the operations are causing significant environmental damage, particularly pollution of the soil with potentially toxic metals (PTMs).  In this study, the speciation of PTMs (arsenic, cadmium, chromium, mercury, manganese, nickel, lead and zinc) from the mine impacted soils of Riruwai mining area was investigated using a modified Tessier sequential extraction method. The findings of the study revealed that all the PTMs examined are considerably associated with non-residual fractions in all the sampling locations. This indicates that all the PTMs investigated in the study area may be highly mobile in the soils and hence potentially toxic. The concentrations of PTMs in the soil’s geochemical fractions were found to vary with the sampling locations, with active mining sites significantly (p ≤ 0.05) recording the highest value, followed by farmland, while the lowest value was reported at the control site. Therefore, to protect the environment and the health of the local populace, PTMs in the soils of the study area should be regularly monitored and a treatment program should be put in place

Chemical Composition and Particle Size Analysis of Kaolin

The mineral and elemental composition, crystal structure and particle size distribution of kaolin clays have been determined to ascertain its industrial significance. The mineral composition is evaluated by X- Ray Fluorescence (XRF), crystalline structure by X-Ray Diffraction (XRD) and particle size distribution using low angle laser light scattering (LALLS) technique. The results shows the presence of eight elements expressed in percentages in form of their oxides as: SiO2, Al2O3, Fe2O3, MgO, CaO, K2O, TiO2 and P2O5. Five crystalline structures are revealed by XRD result. The particle size distribution shows that kaolin particles are mainly in the range of 25–35 µm, while few particles have size distribution varied between 0.4–0.75 μm. The report is found to be in agreement with other researchers

Heavy Metals Contamination Levels in the Vegetables Grown around Riruwai Mining Area, Kano State, Nigeria

Vegetables grown in mining areas can accumulate significant amounts of heavy metals (HMs), which can cause serious developmental disorders and have long-term negative effects on public health. In the present study, the HMs contamination level in vegetables grown around the Riruwai mining area in Kano State, Nigeria, was investigated. Fifteen (15) vegetable samples were collected, including lettuce (Lacuta sativa L.), tomato (Solanum lycopersicum L.), and bean (Phaseolus vulgaris L.), as well as their corresponding soils. The levels of As, Cd, Cr, Hg, Mn, Ni, Pb, and Zn in all the samples were determined using Microwave Plasma Atomic Emission Spectrometry, and the measured concentrations were used to calculate the bioaccumulation factor (BAF). The results of the study revealed that HMs concentrations in the investigated vegetables were found to be significantly high, with the majority of levels exceeding the WHO/FAO (2007) recommended limit, and the concentration of HMs in the soil decreased in the order of Zn > Mn > Cr > Pb > As > Ni > Cd > Hg, with As, Pb, and Zn exceeding the WHO/FAO (2001) recommended limit. Pollution levels were found to significantly differ between HMs and vegetable types. BAF results revealed that cadmium is an accumulator of all the studied vegetables (BAFs > 1), while mercury was found to be an accumulator of L. sativa. Higher concentrations of these metals in vegetables and soil, particularly arsenic, cadmium, lead, and zinc, necessitate immediate scientific attention and further research to determine the optimum concentration required for human health. Planting of vegetables for human and animal consumption should be stopped until this is accomplished

Chemical Composition and Particle Size Analysis of Kaolin

The mineral and elemental composition, crystal structure and particle size distribution of kaolin clays have been determined to ascertain its industrial significance. The mineral composition is evaluated by X- Ray Fluorescence (XRF), crystalline structure by X-Ray Diffraction (XRD) and particle size distribution using low angle laser light scattering (LALLS) technique. The results shows the presence of eight elements expressed in percentages in form of their oxides as: SiO2, Al2O3, Fe2O3, MgO, CaO, K2O, TiO2 and P2O5. Five crystalline structures are revealed by XRD result. The particle size distribution shows that kaolin particles are mainly in the range of 25–35 µm, while few particles have size distribution varied between 0.4–0.75 μm. The report is found to be in agreement with other researchers

Effect of Water Loading on the Chemical Structure and Mechanical Properties of Thermoplastic Tapioca Starch Film

The effect of water (as a primary plasticiser) content on the chemical structure and mechanical properties of thermoplastic tapioca starch (TPTS) film was evaluated. The TPTS films were produced by tape casting technique through mixtures of fixed amount of glycerol and varied contents of tapioca starch and water. There was observed increase in hydrogen bonding interaction between starch and water molecules depicted by the downward shift between 3303-3281 cm-1. The excessive amount of water loading portrayed increase in crystallinity due to free volume movement of the starch particles. The changes in water loading also showed variation in the tensile strength and elongation at break of the TPTS films. This observation is because of the dependence of mobility of polysaccharide plastics on the water content in the premix. Therefore, starch forms entanglements with the plasticisers to form a flexible film

The Influence of Glycerol on Mechanical, Thermal and Morphological Properties of Thermoplastic Tapioca Starch Film

Thermoplastic tapioca starch (TPTS) film was made by tape casting. The viscoelastic behaviour, thermal degradation and surface morphology were investigated using Dynamic mechanical analysis (DMA), Thermogravimetric analysis (TGA) and Scanning electron microscope (SEM) respectively. The DMA result shows that the storage modulus as well as loss modulus of the TPTS films with 0, 5, 10, 15 and 20% glycerol appears to reduce with increase in glycerol content due to phase relaxation as a result of molecular interaction of the starch molecules with glycerol molecules. Whereas, tan δ shows the effect of temperature is higher on the TPTS film with low glycerol content. The thermal degradation of the TPTS is more susceptible to heat as shown by curve 2(e) for film sample with 20% glycerol, showing that higher glycerol content reduces thermal stability of the film. Even though, lowering of glass transition temperature of the TPTS films took effect with the higher concentration of glycerol which proves ease of processibility and workability of the film. The SEM micrographs of fracture surfaces indicate intermolecular miscibility and surface adhesion increases with higher fraction of glycerol content