title: Settling of Bentonite Particles in Gelatin Solutions for Stickwater Treatment

authors: Shamsuddin, Rashid M.

subjects: Science & Technology

abstract: The settling of calcium and sodium bentonite coated with adsorbed protein from gelatin solutions was investigated across pH 3 to 9. The particle settling or sedimentation was achieved at acidic environment regardless of the amount of protein adsorbed by the particles. The settling is attributed to the formation of “house of cards” structure by bentonite platelets and it is strongly influenced by solution pH. The collapse of this formation resulted in floc formation or particle suspension where no settling can be observed. Few possible settling mechanisms were proposed based on the charge balance and interactions between bentonite platelets and protein molecules in the system. The findings are intended for treatment of gelatin-rich stickwater (meat rendering waste water) using bentonite as low-cost adsorbent. Integrating adsorption and settling into one unit operation has multiple benefits; reducing BOD by removing the proteins and bentonite is directly modified with organics and can be recovered via gravity settling for composite additive application.

text: Settling of Bentonite Particles in Gelatin Solutions for Stickwater Treatment The settling of calcium and sodium bentonite coated with adsorbed protein from gelatin solutions was investigated across pH 3 to 9. The particle settling or sedimentation was achieved at acidic environment regardless of the amount of protein adsorbed by the particles. The settling is attributed to the formation of “house of cards” structure by bentonite platelets and it is strongly influenced by solution pH. The collapse of this formation resulted in floc formation or particle suspension where no settling can be observed. Few possible settling mechanisms were proposed based on the charge balance and interactions between bentonite platelets and protein molecules in the system. The findings are intended for treatment of gelatin-rich stickwater (meat rendering waste water) using bentonite as low-cost adsorbent. Integrating adsorption and settling into one unit operation has multiple benefits; reducing BOD by removing the proteins and bentonite is directly modified with organics and can be recovered via gravity settling for composite additive application.

year: 2016

title: Processing, microstructure and high strain rate behaviour of Ti-6Al-4V Alloy produced from a blended mixture using powder compact extrusion

authors: Singh, Ajit Pal

subjects: Blended powder metallurgy

abstract: Powder compact extrusion (PCE) is an innovative way of processing titanium and titanium alloys to produce good-quality material with a wide range of compositions, microstructures and mechanical properties. This paper explores PCE processing of Ti-6Al-4V alloy prepared from a blended powder mixture, containing elemental hydride-dehydride (HDH) titanium powder and master alloy (60Al-40V) powder. The warm pressed compacts of blended powders were sintered using a vacuum sintering furnace prior to β extrusion. The resulting material was used to measure the performance under high strain rate and tri-axial stress state using Charpy v-notch testing. A comparison was made of the microstructure after vacuum sintering and hot extrusion in addition to oxygen measurements to determine the degree of oxygen pickup during each processing stage. A comprehensive study of fracture surfaces in selected samples was carried out using optical microscopy and scanning electron microscopy. Based on the results, it is clear that certain samples picked up varying amounts of interstitial impurities during processing and as a consequence a significant number of micro-cracks were observed in lamellar type microstructures. The oxygen content of all as-extruded samples was between 0.34-0.44 wt.% with resultant impact toughness in the range of 10-14 J. The best impact toughness attained for the lowest oxygen as-extruded rods was 20% lower than the literature values for wrought material. In terms of fracture behaviour, ductile dimples, cleavage facets and cracks passing through lamellar structures were observed in all samples. However, the quantity of these fracture features varied significantly in each sample.

text: Processing, microstructure and high strain rate behaviour of Ti-6Al-4V Alloy produced from a blended mixture using powder compact extrusion Powder compact extrusion (PCE) is an innovative way of processing titanium and titanium alloys to produce good-quality material with a wide range of compositions, microstructures and mechanical properties. This paper explores PCE processing of Ti-6Al-4V alloy prepared from a blended powder mixture, containing elemental hydride-dehydride (HDH) titanium powder and master alloy (60Al-40V) powder. The warm pressed compacts of blended powders were sintered using a vacuum sintering furnace prior to β extrusion. The resulting material was used to measure the performance under high strain rate and tri-axial stress state using Charpy v-notch testing. A comparison was made of the microstructure after vacuum sintering and hot extrusion in addition to oxygen measurements to determine the degree of oxygen pickup during each processing stage. A comprehensive study of fracture surfaces in selected samples was carried out using optical microscopy and scanning electron microscopy. Based on the results, it is clear that certain samples picked up varying amounts of interstitial impurities during processing and as a consequence a significant number of micro-cracks were observed in lamellar type microstructures. The oxygen content of all as-extruded samples was between 0.34-0.44 wt.% with resultant impact toughness in the range of 10-14 J. The best impact toughness attained for the lowest oxygen as-extruded rods was 20% lower than the literature values for wrought material. In terms of fracture behaviour, ductile dimples, cleavage facets and cracks passing through lamellar structures were observed in all samples. However, the quantity of these fracture features varied significantly in each sample.

year: 2016

title: The city of Rotorua and its meaning to Ngati Whakaue

authors: Te Awekotuku, Ngahuia

subjects: New Zealand

abstract: This paper discusses the history and settlement of the city of Rotorua as it relates to Ngati Whakaue.

text: The city of Rotorua and its meaning to Ngati Whakaue This paper discusses the history and settlement of the city of Rotorua as it relates to Ngati Whakaue.

year: 1976-08