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Sweet sorghum (Sorghum bicolor (L.) moench), a crop that is grown by subsistence farmers in Zimbabwe was used to extract silica gel in order to assess its possible use as a raw material for the production of silica-based products. The gel was prepared from sodium silicate extracted from sweet sorghum bagasse ash by sodium hydroxide leaching. Results show that maximum yield can be obtained at pH 5 and with 3 M sodium concentration. The silica gel prepared at optimum pH 5 had a bulk density of 0.5626 g/cm 3 and anestimated porosity of 71.87%. Silica gel aged over 10 h had improved moisture adsorption properties. X-ray fluorescence (XRF) determinations show that the silica content in the ash is 40.1%. Characterization of sweet sorghum ash and silica gels produced at pH 5, 7 and 8.5 by Fourier Transform Infrared spectroscopy gave absorption bands similar to those reported by other researchers.Transmission electron micrographs show that silica prepared under optimum conditions is amorphous and consisted of irregular particles. Sweet sorghum proved to be a potential low cost raw material for the production of silica gel.

Silver nanoparticles were synthesized using Euphorbia Confinalis stem extract which is an eco-friendly and cost effective method compared to other synthesis protocols like chemical and physical methods. Euphorbia Confinalis which is used traditionally for therapeutic uses was responsible for capping and reducing silver ions to silver nanoparticles. Silver was of a particular interest for this process due to its evocative physical and chemical properties. The silver nanoparticles synthesized were quantified and characterized using visual examination of the color changes, UV-Visible spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, Dynamic Light Scattering and Fourier Transform Infrared spectroscopy. The antimicrobial activity of the synthesized nanoparticles was done by agar disc diffusion method tested against Escherichia coli (Gram-Negative) and Staphylococcus aureus (Gram-Positive). The synthesis of silver nanoparticles was confirmed by color change of AgNO3 to reddish brown upon addition of the Euphorbia Confinalis stem extract. The UV-Vis spectrum showed broad absorption band at 433nm corresponding to that of Surface Plasmon Resonance of silver nanoparticles. The FTIR analysis showed the presence of aromatic, aliphatic and amines and these observations suggested the presence and binding of organic compounds with silver nanoparticles.

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A biochar based adsorbent prepared from Eichhornia crassipes-molasses bio-composite was tested for its ability to remove methylene blue from aqueous solutions. Molasses were used as a granulating media for powdered biomass making it easier to prepare the biochar under set conditions. The

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