Silica nano particles synthesized from boiler spent ash: Value addition to an industrial waste

Large quantities of biomass ash are generated everyday by the spice industries and are currently disposed off as landfill. However, this could transform into an environmental pollutant unless alternative techniques are developed for its disposal or value addition. Here in this study, the waste ash from biomass combustion wassuccessfully converted into silica nanoparticles with potential for application in several fields. The highly alkaline nature of the ash and presence of unburned carbon warrants a pretreatment which includes digestion and acid treatment. The synthesized silica was characterized in terms of morphology, specific surface area, crystallinity, surface functional groups and size. Alkaline extraction of the pretreated ash followed by acid precipitation yielded an amorphous structure with minimum mineral contaminants, high surface area, and a narrow size distribution (8-10 nm range) characteristic of nano silica. Studies thus indicate that the waste ash and the extraction process could be fine tuned for the large scale production of amorphous silica and could be of use to solve the problem of boiler ash pollution. Keywords: biomass ash, boiler ash, nano silica, value addition to waste, amorphous silic

Effect of Silver Plasmonic Layer on Cu2O/In2S3 Solar Cell

Solar cell with the structure Cu/Cu2O/In2S3/Ag@NP/Ag was fabricated where the In2S3-window layer and the plasmonic Ag nano particle thin film layer were deposited using injection chemical spray pyrolysis technique. Quantum efficiency measurement of these solar cells showed improved performance in the blue region of the visible spectrum compared to their counterparts. The films with Ag nano particles exhibited surface plasmon resonance peak at 432 nm which could be assigned to plasmon resonance of Ag nano-particles. The open circuit voltage of the best solar cell is 0.65 V, with short circuit current density of 1.2 mA/cm2, fill factor 22% and efficiency 0.17 %. We conclude that the in-coupling of light by the metallic nanoparticle thin film layer into the underlying semiconductor layer resulted in improvement in electrical performance of these solar cells containing the plasmonic Ag nano particles

A three-dimensional phase boundary model for diffusion processes involved in reactions of crosslinked polymeric amines with low molecular weight esters

The reactivity of amino groups attached to N-N'-methylene-bis-acrylamide (NNMBA)-and triethyleneglycol dimethacrylate (TEGDMA)-crosslinked polyacrylamide gels (2–20 mol% crosslinked) has been investigated by following the aminolysis of p-nitrophenyl ester of benzoyl glycine in a mixed solvent. A differential method was employed for following the rate of aminolysis reaction at definite intervals of time. The extent of aminolysis was found to be maximum between 25 and 35 min after initiation for these resins. The rate constants were calculated using the equation for three-dimensional phase boundary model with spherical symmetry and three-dimensional diffusion model. The reaction appears to be a phase boundary process up to 40 min after initiation and thereafter is fully controlled by three-dimensional diffusion. The rate constants do not show any dispersion when this model is used