310 research outputs found
Proceeding of the National Conference Design and Application of Technology 2010. section 3 : industrial engineering : 15th July 2010 Surabaya/ Edit. : Julius Mulyono; Yuliati; Suryadi Ismadji
No full textvii, 160 hal.: ill, tab.; 29 cm
Insights on the statistical physics modeling of the adsorption of Cd2+ and Pb2+ ions on bentonite-chitosan composite in single and binary systems
No full textIn this study, a bentonite-chitosan composite was tested for the single and binary adsorption of Cd2+ and Pb2+ ions at constant pH (6) and different temperatures (30, 40, and 50 degrees C). For both adsorbates, the adsorption capacities decreased in binary systems due to an antagonistic adsorption effect. Statistical physics models were used to analyze the adsorption isotherms and to attribute microscopic interpretations to the experimental evidences at a molecular level. Specifically, a monolayer model with one energy and an exclusive extended monolayer model were applied to single and binary adsorption data, respectively. The crossing of the experimental and modelling results proved that Cd2+ ion was more adsorbed in the binary system. The modelling analysis allowed determining that the numbers of ions linked per adsorbent site varied significantly in binary system with respect to single-compound ones, thus confirming that an inhibition effect occured. Finally, the adsorption energy was estimated for both adsorption systems indicating the occurrence of an endothermic adsorption. Moreover, adsorption energies showed concordant trends with the corresponding adsorption capacities of both Cd2+ and Pb2+, hence being able to describe the adsorption phenomena
Periodic mesoporous silica and organosilica with controlled morphologies as carriers for drug release
No full textIn this paper, we report the effects of morphology, wall composition of mesoporous materials and different buffer solutions on drug delivery profiles. Hollow spheres of periodic mesoporous organosilica (PMO) were prepared and used as drug carriers which exhibited higher loading capacity and slower release rate compared to the conventional periodic mesoporous silica (PMS) spheres and solid spheres of PMO. This hollow PMO showed promising properties as a reservoir to encapsulate and store larger quantities of guest molecules within its "empty" core. Moreover, its organic reactive sites allowed stronger interactions to the hydrophobic guest molecules, in contrast to inorganic wall possessed by PMS materials. Antibiotic tetracycline was used as a model drug to study the effect of framework difference between PMO and PMS materials on the loading and release processes. Two kinds of release medium, simulated body fluid (SBF) solution (pH 7.4) and phosphate buffer (PB) solution (pH 1.5) were used in this study, which revealed very different release profiles. A slower delivery rate was observed in SBF solution, attributed to the different ionic interactions between the guest molecule and the host material in the two different pH solutions. Overall, hollow PMO shows the lowest release rate and the highest loading amount compared to the other two materials studied herein. The kinetic study reveals that drug release from host material follows the second order kinetic model better than the first order mass transfer model. © 2008 Elsevier Inc. All rights reserved.Chun Xiang (Cynthia) Lin, Shi Zhang Qiao, Cheng Zhong Yu, Suryadi Ismadji, Gao Qing (Max) L
New insights into single-compound and binary adsorption of copper and lead ions on a treated sea mango shell: Experimental and theoretical studies
Full text linkHerein, adsorption isotherms of Pb(II) and Cu(II) ions on treated sea mango fruit in both single-compound and binary systems were experimentally realized at different temperatures in the range of 30-50 degrees C. Experimental results show that adsorption of Pb(II) was more as compared to that of Cu(II) ions; however, for both ions, a significant reduction in the adsorption capacity was observed in the binary system as compared to that in the single-compound systems. Moreover, under all the investigated conditions, adsorption seems to be promoted by an increase in temperature. To understand and interpret the experimental evidences, the Hill and competitive Hill models developed on the basis of the grand canonical ensemble were applied for the analysis of adsorption equilibrium data. These models contain some physicochemical parameters that allow an exhaustive analysis of the dynamics of single-compound and binary adsorptions. Based on the fitting results, in particular, through the evaluation of the number of ions bonded per site (n and n(i)), it was found that lead and copper ions interacted by inclined and horizontal positions on treated sea mango in single-compound and binary systems, respectively. In addition, based on the same parameters, a significant interaction between ions was retrieved. A study focused on the saturation adsorption capacity in single-compound and binary systems affirmed that the adsorbent was more selective for lead than for copper. The reduction of the adsorbed capacity ratio between the binary and single-compound systems (i.e. Q(b)/Q(s)) explained and confirmed that an inhibition effect between copper and lead ions at the same receptor site occurred. Finally, based on the energetic investigations, it was deduced that the adsorption energy represented the dominant factor promoting the greater adsorption of lead than that of copper in both systems
Molecular insights through computational modeling of methylene blue adsorption onto low-cost adsorbents derived from natural materials: A multi-model's approach
No full textThe fundamental phenomena involved in methylene blue adsorption onto three different activated car- bons (a raw adsorbent and two samples derived from either chemical or thermal treatment of the raw sample) are elucidated by coupling different multi-physics modeling approaches. Statistical physics ap- proach leads to understand that methylene blue adsorption is mainly affected by the porosity of sorbents rather than their functional groups. Electrostatic interactions, Van der Waals forces or hydrogen bonding might occur between dye cations and carboxylate anions on adsorbent surface. The quantum chemical calculations suggest that dispersive interactions and pore characteristics of the activated carbon derived from thermal treatment predominantly contribute. The investigated reactive sites show that the same preferable sites for both electrophilic and nucleophilic attacks are detected for the sample derived from thermal treatment, allowing explaining the best performances of this adsorbent. Finally, the most sta- ble energy configuration of methylene blue adsorption on activated carbon is obtained by Monte Carlo simulations
Optimization of cellulose nanocrystals from bamboo shoots using Response Surface Methodology Author links open overlay panel
Full text linkCellulose-based advanced materials, such as cellulose nanocrystals (CNC), have high potential application for
drug delivery system. In this study, the CNC were produced from bamboo shoots using acid hydrolysis process.
The delignification of bamboo shoots was conducted using alkali and hydrogen peroxide pretreatment processes.
The operating condition of the production of CNC from bamboo shoots was optimized using Response Surface
Methodology (RSM) based on the yield and crystals recovery as the responses. The optimum CNC yield of 50.67 �
0.74% with a crystals recovery of 77.99 � 1.14% was obtained at the sulfuric acid concentration of 54.73 wt%
and a temperature of 39 �C from the optimization based on the yield. This optimization has been validated to
confirm the accuracy
Current progress on the production, modification, and applications of bacterial cellulose
Full text link58 p.-5 fig.-3 tab.Adoption of biomass for the development of biobased products has become a routine agenda in evolutionary metabolic engineering. Cellulose produced by bacteria is a "rising star" for this sustainable development. Unlike plant cellulose, bacterial cellulose (BC) shows several unique properties like a high degree of crystallinity, high purity, high water retention, high mechanical strength, and enhanced biocompatibility. Favored with those extraordinary properties, BC could serve as ideal biomass for the development of various industrial products. However, a low yield and the requirement for large growth media have been a persistent challenge in mass production of BC. A significant number of techniques has been developed in achieving efficient BC production. This includes the modification of bioreactors, fermentation parameters, and growth media. In this article, we summarize progress in metabolic engineering in order to solve BC growth limitation. This article emphasizes current engineered BC production by using various bioreactors, as well as highlighting the structure of BC fermented by different types of engineered-bioreactors. The comprehensive overview of the future applications of BC, aims to provide readers with insight into new economic opportunities of BC and their modifiable properties for various industrial applications. Modifications in chemical composition, structure, and genetic regulation, which preceded the advancement of BC applications, were also emphasized.This project was supported by the Ministry of Science and Technology, Taiwan [MOST 106-2628-E-002-009-MY3Peer reviewe
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