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Organosilane and lignosulfonate: Road subsurface layers stabilisers
Published in A. Kumar, A.T. Papagiannakis, A. Bhasin, D. Little, Advances in Materials and Pavement Performance Prediction II, 2020
D. M. Barbieri, I. Hoff, S. Adomako, C. Hu
Organosilane, here referred to as polymer-based agent (P) as well, is derived from nanoscale technology. It converts the water absorbing silanol groups presented on the silicate-containing surface of the rocks to a 4-6 nm layer of hydrophobic alkyl siloxane resulting in near permanent modifications.
Some Chromatographic Peculiarities of Polymer-Mineral Packing Materials with Octadecyl- and Butyl-Functional Groups
Published in Omari V. Mukbaniani, Tamara N. Tatrishvili, Marc J. M. Abadie, Science and Technology of Polymers and Advanced Materials, 2019
S. S. Hayrapetyan, M. S. Hayrapetyan, G. P. Pirumyan, H. G. Khachatryan
Silanol groups left on the surface due to incomplete derivatization play an important role in retention mechanism. Therefore, studies were undertaken to understand the influence of silanols on retention and peak shape [3]. The retention of most compounds with basic functional groups depends not only on the bonded phase properties, but on the amount of silanol groups available for interaction with the analyte. Thus, complete characterization of the properties of reversed-phase packings should test not only hydrophobic properties of a packing, but also the “silanol” activity.
Sol–Gel Processing
Published in M. N. Rahaman, Ceramic Processing and Sintering, 2017
The chemistry of silica in aqueous systems (e.g., sodium silicate) is discussed in detail by Iler (10). Silicon is hydrolyzed even in dilute acid and as shown in Fig. 5.4, silicic acid [Si(OH)4], often referred to as monosilicic acid, orthosilicic acid, or soluble silica, is the dominant mononuclear species in solution below pH values of ˜7 (11). The Si-OH group is called a silanol group, indicating that Si(OH)4 contains four silanol groups. Above pH ≈ 7, further hydrolysis produces anionic species:
The emergence of nanoporous materials in lung cancer therapy
Published in Science and Technology of Advanced Materials, 2022
Deepika Radhakrishnan, Shan Mohanan, Goeun Choi, Jin-Ho Choy, Steffi Tiburcius, Hoang Trung Trinh, Shankar Bolan, Nikki Verrills, Pradeep Tanwar, Ajay Karakoti, Ajayan Vinu
Current drug delivery approaches demand a carrier that can deliver the drug in the targeted area with longer blood circulation and retention time. To achieve the desired properties, the current generation of drug delivery carriers is modified by functionalizing the surface to attach various agents for imaging, tracking, targeting, and releasing drug molecules. In addition, the surface functionalization presents an opportunity for stimuli-responsive drug delivery by the use of gate-keeper molecules or by attaching drugs covalently to the surface of particles using specific stimuli-responsive bonds that can be broken in the presence of external or internal stimuli to release the attached drugs. In this respect, MSNs with a high density of surface silanol groups have the edge over all other materials. The surface silanol groups can be directly functionalised with various groups or can be converted to more suitable functional groups, such as thiol, amine and carboxyl, for further attachment with ligands and/or drugs. Scheme 6 depicts a strategy that can be used for attaching two different surface functional groups. This strategy can be further used for the conjugation of two different entities, such as a drug and a fluorescent agent. In addition, the advancements in silane chemistry have resulted in the availability of various types of silanes with terminal functional groups. These silanes can be co-condensed during the synthesis of silica or can be grafted on the surface post-synthesis of silica, giving even greater flexibility for the functionalisation of MSNs.
A study on optimization of acid sites concentration versus pore dimensions in modified solid acid catalysts for biodiesel production
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Nasser H Shalaby, Mamdouh S. Elmelawy, Salah A. Hassan
The texturally modified RHS was soaked in distilled water for 3 weeks followed by refluxing for 3h to generate surface silanol groups by hydrolyzing siloxane groups on the surface of the calcined (BTZ-MS) (Chen et al.1999). The mesoporous silica was separated by filtration and dried in an electric oven at 105°C for 3h. The rehydroxylated mesoporous silica was thermally analyzed for determination of accessible silanol groups. A 15 g of rehydroxylated mesoporous silica (containing 0.0483 mol of OH) was dispersed in 150 ml of CH2Cl2 in a two-neck round bottom flask. Chlorosulfonic acid (0.0161 mol, being equivalent to one third of accessible OH groups on silica surface) was dissolved in 100 ml CH2Cl2 and added over a period of 30 min under stirring, by using a constant-pressure dropping funnel. The evolved HCl gas was absorbed in cold water adopting a gas-washing bottle. After the complete addition, the mixture was stirred for further 1h. The brown functionalized silica was collected by filtration and washed with 150 ml methyl t-butyl ether and left in the open air to dry (Zolfigol et al. 2013). The prepared solid acid was denoted as BTZ-MS-S1.
Preparation of synthetic composite nano-catalyst for oxidative desulfurization of kerosene
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Hamin Jafaar Mohammed, Aysar T. Jarullah, Ban A. Al-Tabbakh, Hala M. Hussein
The nano silica support and catalysts chemistry of the surface especially surface acidity and the materials incorporation confirmed successfully via FT-IR spectroscopy technique. The outcomes of nano silica depicted in Figure 5. The peaks represent Si–O–Si asymmetric extending of bridging oxygen within the tetrahedral at 1060.7 cm−1, and the peak of Si–O–Si symmetric extending methods of bridging oxygen between tetrahedral is at 798.4 cm−1. At 443.5 cm−1, the band centered because of the bending frequency of Si-–O–Si. Also, the peak for the silanol (Si-OH) group at 956.5 cm−1 was detected. The FT-IR results for both prepared CAT-1 and CAT-2 are shown in Figure 6. The results indicated that the bands appeared in the region between 3397 and 3800 cm−1 reported depending on the nano silica support surface that there is –OH stretched vibration of adsorbed water particles or silanol. Characteristic bands at 1640 cm−1 detected the bending vibration of the water particles trapping in nano silica. The peaks represent Si–O–Si asymmetric extending of bridging oxygen within the tetrahedral at region 1060.7 cm−1, and the peak of S–-O–Si symmetric extending methods of bridging oxygen between tetrahedral is noticed between 802.2–794.5 cm−1. At 447.4–431 cm−1, the band centered because of the bending. The presence of a band between 990 and 1000 cm−1 indicates the Si–O stretching vibration of the silanol group frequency of Si–O–Si is found. As explained above, it may be inferred that the results of FT-IR for synthesized catalysts match the usual absorption peaks of a commercia behavior (Ali and Disher 2019).