The need to divulge the rapid synthesis, non-hazardous, cost effectiveness and eco-friendly methods for the synthesis of nanoparticles utilizing plants is of great importance. This is as a result of high toxicity associated with the chemical method of synthesizing nanoparticles. The aim of this study was to investigate the potency of the synthesized gold nanoparticle against selected human pathogens. Gold nanoparticles were synthesized by reacting 1 mM gold chloride solution with leaf extract of Annona muricata. The synthesized gold nanoparticles were characterized with UV-visible spectrophotometer, transmission electron microscope (TEM) and Fourier transformed infrared spectroscopy (FTIR). The antibacterial and antifungal activities of the synthesized gold nanoparticles were also investigated. The morphology, size, and structural properties of synthesized gold nanoparticles were determined with TEM analysis which showed spherical mono-dispersed structure with an average particle size of 25.5 nm. FTIR analysis reveal band at 3271.14, 2111.91 and 1637.82 cm −1 corresponding toN -H,-C=C, and-C-N functional groups that are responsible for the capping and stabilization of synthesized gold nanoparticles. The effectiveness of the gold nanoparticle against the test pathogens increases as the concentration of gold nanoparticle increases. The percentage of zones of inhibition of synthesized gold nanoparticle against test fungi and bacteria ranges from 30 to 66% and 40 to 54%, respectively. The potency of the synthesized gold nanoparticle against the selected fungi and bacteria increases with increase in concentration of gold nanoparticle. Therefore, the antibacterial and antifungal investigation revealed that the synthesized gold nanoparticles exhibited good antimicrobial activity.

This research developed a mathematical model and optimization of materials for the development of metakaolin self-compacting concrete. This is in a bid to reduce the overall material quantity and cost towards sustainable infrastructural construction. To achieve the aim of this research, Response Surface Analysis (RSM) was used. Kaolinitic clay was De-hydroxylated at 750°C to form metakaolin. This was used as a partial replacement for cement at 0%, 5%, 10%, 15%, 20% and 25% weight of Portland limestone cement. Both strength and rheology properties of the developed metakaolin self-compacting concrete were assessed. To this end, slump flow, L-Box test and V-funnel test were carried out alongside the compressive strength using relevant standard. The result of the research revealed that at 15% addition of metakaolin the slump flow, passing ability and filling ability was unsatisfactory according to EFNARC standard. From the numerical optimization of the compressive strength, the maximum predicted compressive strength of 44.35 N/mm 2 was obtained. At a low value of metakaolin addition (5-15%), the compressive strength increased as the age of the concrete increased from 3-150 days. The age with the optimum mechanical strength formation was 110 days with metakaolin addition of 52.73 kg. The result of this research provide a database for Engineers, Researchers and Construction workers on the optimum metakaolin required to achieve satisfactory mechanical strength in metakaolin self-compacting concrete.

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Hydrolysis of waste polyethylene terephthalate (PET) into terephthalic acid (TPA) is a promising recycling method to manage this waste and can also serve as a feedstock for the re-production of PET. However, the drawbacks of this recycling method are the low degradation efficiency, complex/ecounfriendly separation of products, and low TPA purity. In this work, waste PET bottles were completely depolymerized using an uncatalyzed neutral hydrolysis, which was accompanied by a very simple solid product separation with no purification step. The influences of experimental parameters, such as hydrolysis time, the addition of ethylene glycol cosolvent, and the PET/water ratio on the TPA yield and purity, were investigated. Qualitative analyses showed that the solid product from the hydrolysis process was TPA, which was consistent with commercial purified TPA. The results showed that a long hydrolysis time, in the absence of any catalyst and a very high PET/water ratio, favored increased TPA yield, selectivity, and purity. The TPA yield increased from ∼86 to ∼98% as the hydrolysis time increased from 6 to 24 h. Furthermore, the TPA consisted of large particles and was easy to obtain without any complex extractive and purification processes. This facile and green approach for the depolymerization of waste PET to pure TPA with no isolation/purification steps promises a more efficient and inexpensive route for its full commercialization.