Lean Condition Procedure for Utilization of Silica from Rice Husk as Zeolite Precursor

Rice husk is rich in Si that makes it applicable as Si source for zeolite synthesis. However, the conventional method to use rice husk as a zeolite precursor has some drawbacks, which are: Si recovery method that involves burning and causing air pollution and carbon resources loss; and the use of severe conditions and sophisticated apparatuses which are not suitable for rural application where rice husk is mainly produced. In this paper, a method to prepare rice husk as zeolite Si source via a non-combustion process was proposed. Furthermore, its utilization as a zeolite precursor via moderate condition was also investigated. Si was recovered directly from rice husk using a sodium hydroxide solution. Si was successfully recovered from rice husk, and the optimum condition for recovery was found to be 1 N of NaOH and 16 hours of contact time. The application of the recovered Si for zeolite precursor at moderate condition was successful, and it was able to produce a product rich in zeolite P and zeolite X depending on the condition. Among zeolites synthesized in this experiment, the sample prepared by treatment time of 15 hours showed the highest cation exchange capacity, which makes it a promising material to be used as an ion-exchange agent.

Influence of Ethanol Concentration and Template Ion Exchange Agent on Template Recycling in Mobil Crystalline Material 41 (MCM-41) Synthesis

Recycling of surfactant template for several subsequent MCM-41 synthesis is necessary to reduce substantial synthesis solution disposal. In MCM-41 synthesis, ethanol concentration and template ion exchange agent are two significant factors that affect the silicate polymerization, solvating effect on micelles formation, and MCM-41 mesostructure formation. In view of that, this study investigates recycling of surfactant template ions in extract solution in Mobil Crystalline Material 41 (MCM-41) synthesis. Effect of the ethanol concentrations in the solution gel and the types of ion exchange agents on the yield of MCM-41 material and its surface morphology were studied. Hexadecyltrimethylammonium bromide was used as template for MCM-41 synthesis using tetraethylorthosilicate (TEOS) as silica reagent with ethanol-water mixture as solvent at different ethanol concentrations. Template ions of synthesis gel was exchanged with an ion exchange agent (i.e., 1-butyl-3-methylimidazolium chloride or ammonium nitrate) before it is extracted using synthesis solution. After extraction, the extracting solution was added with TEOS, used for second synthesis cycle and the process continued in an extraction. The template ions in the extract solution were further recycled up to eight synthesis cycles. Yield of calcined materials significantly influenced by ethanol solvent concentrations and however did not vary with various ion exchange agents. Nitrogen adsorption isotherms showed that the calcined materials exhibit MCM-41 characteristics with surface areas ranging from 600 – 1000 m2/g. It is possible to recycle and reuse the surfactant template for several subsequent times of preparing MCM-41 if the ethanol concentration in the solution gel controlled continuously.

Template Recycling and Reuse in MCM-41 Synthesis: Statistical Study

The recycle and reuse of template in MCM-41 synthesis were analysed using 23 full factorial design in order to study the effect of the template extraction parameters on the mass of MCM-41 powder produced. Four consecutive MCM-41 synthesis cycles utilizing the recycled template were studied with three factors that are ethanol fraction (A), amount of ion exchange agent (B) and the type of ion exchange agent (C). The significant effects contributed by the factors A, B and C and their interactions were identified through the half-normal probability plot and normal probability plot of the residuals. F-test and t-test were carried out to test the contribution of regression coefficients for synthesis cycles of MCM-41 synthesis models. AB interaction showed that larger mass of MCM-41 powder was obtained at high ethanol volume fraction and high quantity of ion exchange agent when either type of ion exchange agent was used.

Trabajo Social en la realidad española en los años 1960 a 1980: a la búsqueda de autodefinición y reconocimiento profesional

Resumen: En este artículo presentamos los análisis, aún preliminares, de los movimientos contestatarios experimentados por el Trabajo social en España en el período de 1960 a 1980, y que mantienen una relación indisociable con el movimiento macro societario interno de la sociedad española, y externamente, a partir del ingreso del Estado Español en los mecanismos de las políticas internacionales desarrollados especialmente por los Estados Unidos desde los años 1950. Dentro de ese período, el Movimiento de Reconceptualización Latinoamericano fue conocido entre los trabajadores sociales españolas, pero su influencia no se generalizó, apareciendo en segmentos de la profesión con posiciones politizadas más progresistas, reconociendo su importancia y buscando una producción teórica e intervencionista de la profesión adaptada a la realidad española. Palabras-clave: movimiento de reconceptualización; trabajo social en España; movimientos contestatarios; agente de cambio; análisis crítico. Resumo Neste artigo apresentamos as análises, ainda preliminares, dos movimentos contestatórios experimentados pelo Serviço Social na Espanha no período de 1960/1980, e que mantêm relação indissociável com o movimento macrossocietário interno da sociedade espanhola, e externamente, a partir do ingresso do Estado Espanhol nos mecanismos de políticas internacionais desenvolvidos especialmente pelos Estados Unidos, desde os anos 1950. Dentro desse período, o Movimento de Reconceituação Latino-americano foi conhecido entre os trabalhadores sociais espanhóis, mas sua influência não se generalizou, aparecendo em segmentos da profissão com posições politizadas mais progressistas, ora reconhecendo sua importância, ora buscando uma produção teórica e interventiva da profissão adaptada à realidade espanhola. Palavras-Chave: movimento de reconceituação; trabalho social em Espanha; movimentos contestatórios; agente de câmbio; análise crítica. Abstract – In this article we present the preliminary analysis of the contestatory movements experimented by social work in Spain in the period of 1960-1980, which is inseparable from, internally, the Spanish macro-society movement, and externally, the adoption by Spain of international policy mechanisms developed especially by the United States since the 1950s. In this period, the Latin American reconstruction movement was known among Spanish social workers, but its influence was not generalized, appearing in segments of the profession with politicized and more progressive stances. These segments recognized its importance, but also sought a theoretical and interventionist production of the profession adapted to the Spanish scenario. Keywords: reconceptualization movement; social work in Spain; contestatory movements; exchange agent; critical analysis.

BENGKEL SASTRA BALAI BAHASA DIY DALAM PERSPEKSTIF SOSIOLOGI PIERE BOURDIEU

Yogyakarta in Indonesia literature is one of the literary arenas that are unseparated from prominent literary writers in Indonesia, such as Korrie Layun Rampan, WS. Rendra, Emha Ainun Nadjib, etc. Those writers are associated to literature community surrounding, such as Korrie Layun Rampan and Emha Ainun Nadjib whose were members of Persada Studi Klub (PSK) in 1969-1977 era. After PSK had dismissed, many literary community appeared to enlighten literary atmosphere in Yogyakarta. In 2000s, Studio Pertunjukan Sastra (SPS) and Sastra Bulan Purnama (SBP) appeared with different ways and styles in activating and appreciating literary works. Before those communities appeared, in 1996, a program (community) had born named Bengkel Sastra (BS) in the initiative of Balai Penelitian Bahasa Yogyakarta (now Balai Bahasa DIY). Bengkel Sastra (BS) offers creative process with applied practices in writing and oral expression through literary performance. BS becomes arena of modal transfer from tutor to participants. The transfer modal enable modal investment of BS's participants in preparing them to be writers in future. This research will focus on modal exchange, agent, and legitimate in BS. To explain those matters, this research used sociology theory of Pierre Bourdieu, particularly modal exchange and legitimate in agents in BS. This research is descriptive. The result shows that BS offers legitimate to agent (participants), although little, to enter literary world through celebrating works (books), and literary works performance orally.

Preparation and Properties of Rectorite/Epoxy Nanocomposites

The Org-rectorite, which was used as a filler in the Rectorite/Epoxy nanocomposites, was prepared by the intercalation and exfoliation of rectorite with dodecyl-bis (2-hydroxyethyl)-methylazanium chloride as the organic cation exchange agent. The two curing agents methyl hexahydrophthalic anhydride (MHHPA) and m-phenylenediamine were employed at working temperature ranging from 70 °C to 190 °C. The samples were characterized by Fourier Transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) analysis. The results show that the d001 (55.9 Å) of Rectorite/Epoxy composites cured with MHHPA at 70 °C was larger than the Org-rectorite (28.7 Å), and the Org-rectorite was exfoliated at 90 °C working temperature. While the d001 of Rectorite/Epoxy composites cured with m-phenylenediamine at 70 °C and 90 °C were 40.9 Å and 42.1 Å , and were exfoliated at 140 °C. The apparent activation energy (Ea) of Rectorite/Epoxy composites cured with MHHPA and m-phenylenediamine were obtained to be 74.85 and 59.15 KJ/mol, respectively. The higher apparent activation energy (Ea) of MHHPA systems may be responsible for the lower exfoliation temperature.

THE APPLICATION OF TAPANULI CLAY AS NANOFILLER IN NANOCOMPOSITES: SYNTHESIS AND THEIR CHARACTERIZATION

Organo layered silicates (OLS) were successfully synthesized from Tapanuli clay through an intercalated ultrasonic method using hexadecyltrimethylamonium bromide ( HDTMABr ) as a cation exchange agent. Tapanuli clay–epoxy nanocomposites were also successfully synthesized with an in-situ polymerization. X-Ray Diffraction and Transmission Electron Microscope (TEM) results demonstrated a pattern of clay morphology typically found in nanocomposite systems. Although the nanocomposites' diffractogram showed an exfoliation structure, the TEM findings confirmed that the OLS d -spacing is between 2.58 nm (the minimum value) up to 14.74 nm (the maximum value); which indicates the nanocomposites posses a mixed structure between intercalated and exfoliated structures. It was found that the presence of 1wt% Tapanuli organo clay in the epoxy systems provides higher stiffness and higher Heat Deflection Temperature by 30 % and 7 % respectively.