China
Africa
Explore chapters and articles related to this topic
Numerical simulations of potential oil spills near Fernando de Noronha archipelago
Published in C. Guedes Soares, T.A. Santos, Trends in Maritime Technology and Engineering Volume 2, 2022
P.G.S.C. Siqueira, J.A.M. Silva, M.L.B. Gois, H.O. Duarte, M.C. Moura, M.A. Silva, M.C. Araújo
The meteo-oceanographic conditions and physico-chemical processes brought a high parcel of the oil that first reaches the FNA within 20h. A total amount of around 63.95% of oil (~5819 t) of oil is on the archipelago shore or sedimented on the shallow water depths by the end of the simulation. This is illustrated in Figure 7F, when little oil is still being transported. The advective transport makes the time window for an effective response very narrow, potentially intensifying the impacts. Furthermore, mitigation actions such as the use of dispersants are very toxic to the environment (Shafir et al., 2007). Thus, preventive actions should be prioritized instead of mitigating measures.
The Processes for Stabilizing Suspensions for Ceramic Thermal Barrier Coatings (TBC)
Published in Navid Hosseinabadi, Hossein Ali Dehghanian, Suspension Plasma Spray Coating of Advanced Ceramics, 2022
Navid Hosseinabadi, Hossein Ali Dehghanian
The repulsive steric potential is dependent on Flory-Huggins parameter χ (wettability of the dispersant in the medium), adsorbed layer volume fraction ϕa, layer thickness δ, molar volume of the solvent v1, and temperature T. The following conditions are required for a good steric dispersion. The complete coverage of particle surface by the steric layer (high ϕa), sufficient thickness of the adsorbed layer (δ > 5 nm), medium as a good solvent for the stabilizing chain (χ < 0.5), and strong attachment of dispersant with the surface particle are achieved with anchor groups of strong affinity with the surface. On the other hand, if the polymer is not attached to the surface but freely moves dissolved in the solvent, it can produce depletion agglomeration instead of dispersion. Therefore, the high affinity of the dispersant with both ceramic particle and solvent medium is fundamental for good dispersion, which can be evaluated with the use of contact angle measurements.
Ceramic Capacitor Technology
Published in Lionel M. Levinson, Electronic Ceramics, 2020
Manfred Kahn, Darnall P. Burks, Ian Burn, Walter A. Schulze
The purpose of dispersion is to keep the particles from reagglomerating. This is necessary to permit an intimate mix of all the ingredients. These include not only the different inorganic ingredients, but also the binders and solvents that form a slip or paint suitable for preparing the green dielectric layer. About 10% of a binder (i.e., PVA or an acrylic resin) is often used. The dispersant is essentially a surfactant that with proper pH control permits intimate wetting of the surfaces of the particles. Fully dispersed slips provide a maximum solids loading with a minimum viscosity.
Sapindus laurifolia: an eco-friendly alternative to synthetic dispersants for limestone transportation
Published in Journal of Dispersion Science and Technology, 2023
Asisha Ranjan Pradhan, Satish Kumar
Dispersants are surface-active substances that improve the wettability of particles by lowering the surface tension of a liquid, hence reducing the interfacial tension between solid particles and the liquid in a slurry system. Using a surface tensiometer, the surface tension of the surfactant in the aqueous extract is being investigated (DCAT-21, Dataphysics, Germany) using the William plate method. Surface tension has been measured by gradually varying the surfactant concentration from 0.01 to 0.03 g/cc. The connection between the concentration of saponin and the surface tension of an aqueous solution is shown in Figure 2. It is clear that the surface tension of the surfactant mixed water rapidly lowers as the concentration of saponin rises. The surface tension decreases with the increase in the exchange of solvent molecules by the surfactant at the interface.[48] When saponin concentration is at 0.018 g/cc (1.8 wt. percent), surface tension saturates to a minimum of 44 ± 0.2 mN/m from pure water’s 72.76 ± 0.2 mN/m. Thus, it was discovered that the saponin’s critical micellar concentration (CMC) was 1.8 wt%.
Effect of comb polymer dispersants with different molecular structures on the performance of LiFePO4 suspensions
Published in Journal of Dispersion Science and Technology, 2023
Yarui Dong, Jian Xu, Ping Du, Zhongjun Feng, Baicun Zheng
Adding polymer dispersant to the slurry can effectively prevent particle agglomeration and improve the dispersion and stability of the suspension.[8–10] The dispersant is adsorbed to the particle surface to improve the particle dispersion performance by transforming the particle/particle and particle/liquid medium interactions. Among all kinds of dispersants commonly used, comb polymer is widely used in cement, dye, ink and coal water slurry[11–14] because of its superior dispersion stability. A typical comb polymer consists of a backbone with anchoring groups and side chains grafted to the backbone at frequent intervals. The anchoring group on the skeleton mainly plays the driving role of adsorption on the surface of inorganic particles, while the side chain mainly plays the role of spatial repulsive force to dominate the dispersion behavior of inorganic particles in suspension system.[15,16] Many studies have revealed the influence of comb polymer on dispersion performance.[17,18] However, most of the reports of comb polymers are focused on studying their performance in aqueous systems.[19–21] Although the inorganic particles such as carbon black, LiFePO4 are well recognized as the important battery materials used in organic composite. Developing comb polymeric dispersants for non-aqueous systems is extremely valuable.
Preparation of stable dispersion of graphene using copolymers: dispersity and aromaticity analysis
Published in Soft Materials, 2019
Sabih Qamar, Saima Yasin, Naveed Ramzan, Tanveer Iqbal, Majid Niaz Akhtar
Structure of polymeric dispersants plays major role in the adsorption of block copolymer dispersants on graphene surfaces. Lugalvan BNO12 adsorbs more on the graphene particles due to the presence of naphthol anchor group having two benzene rings in its structure as compared to other dispersants Triton X100 and Triton X405 which contain one benzene ring in alkyl phenyl anchor chain. The adsorption of polymers on graphene surfaces prevents agglomeration of graphene, and thus improves the quality and the stability of dispersions. Polymeric dispersants having benzene ring in their structure were proved as good stabilizer for aqueous graphene dispersions. FTIR and TGA investigations suggested that the polymer molecules have been grafted to the graphene surface. Dispersants effectiveness was proved from rheological measurements by providing lower values of viscosities at optimum concentration of dispersants. Lugalvan BNO12 showed lowest value of viscosities as compared to that of the other dispersants, and same consistency was observed for electrical conductivity. Therefore, the polymeric stabilized dispersions of graphene may be used for the fabrication of batteries, sensors, and super capacitors applications.