Substantial applications of silica materials in industrial products have caused development of silica extraction methodologies out of various waste products. Rice husk /straw and wheat husk/straw (agricultural waste) are one of the agricultural wastes which have a huge content of silicate materials. This review shows that silica production techniques by using thermal and chemical methods, and also provide directions to efficient, new, rapid microwave assisted method for silica extraction from agricultural waste stream. Index Terms-agricultural waste, nano amorphous silica, thermal treatment, chemical treatment, microwave technology
Drilling fluids are designed to assist drilling by minimizing reservoir damage and increasing productivity of pay zone. Excess fluid loss due to degradation of additives of drilling fluids causes a major problem in real-time drilling. Usages of excess biocides are threat to the environment and cause handling problems. Effect of cetyltrimethylammoniumbromide, a cationic surfactant, on rheology, fluid loss and biocide has been studied in a polymer-based drilling fluid. Inhibitive polymer mud was formulated using XC polymer, shale inhibitors like KCl, K 2 SO 4 and CaCO 3 as bridging agent. Rheology and other properties were studied using Fann VG meter, API filter press, mud balance, roller oven apparatus. Dissolved oxygen meter was used to check the microbicidal property of cetyltrimethylammoniumbromide.Addition of cetyltrimethylammoniumbromide increased fluid retention capacity of the fluid even at very low concentration 0.1%(w/v) without affecting the mud properties. Also it is compatible with the commercially available fluid loss preventers like pre-gelatinized starch when used in combination. It also performed well in dissolved oxygen test, suggesting eliminating need of any other biocide to prevent degradation of bio-polymer-based drilling fluid. The dissolved oxygen test results are comparable with commercial available biocides. Thermal stability studies were carried out by using roller oven at different temperatures. It was found suitable for application in high-concentrated brine conditions and at high temperatures up to 120°C without effecting the rheology and shear thinning property of the fluid. Bridging efficiency was investigated by analysing the mud cake using scanning electron microscope.
Silica gel was prepared by using alkaline extraction and acid neutralization method from ash obtained wheat straw, an agricultural waste. Microwave digestion, followed by calcination was used for obtaining ash. X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) studies revealed the ash to be mostly amorphous silica. Alkaline-solubilization and acidneutralization method was used to obtain gel from silica obtained from wheat straw. Gel was characterized using FTIR. Nitration reaction of benzaldehyde using the silica gel (as acid catalyst) and copper nitrate was successfully carried out.
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