Hens Saputra

Synthesis of zirconium-containing mesoporous silica Zr-MCM-48 membranes with high alkaline resistance for nanofiltration

Abstract Mesoporous silica containing zirconium (Zr-MCM-48) membranes were synthesized on a porous alumina support. The Zr-MCM-48 membranes showed high stability in the alkaline solution of pH 12, indicating that only 3 % of Zr effectively enhanced the alkaline resistance. The permeation of gases through the calcined Zr-MCM-48 membrane was governed by the Knudsen diffusion mechanism. There was no contribution of viscous flow, which occurs in large pinholes. The result of permporometry measurements suggested the narrow pore size distribution of the membrane.

MFI Zeolite Membrane from Rice Husk for Biofuels Production

High silica MFI zeolite membrane was synthesized by hydrothermal method at 313 K on asymetri pore structure alpha alumina substrate, utilizing natural rice husk as the sources of silica. The top layer of substrate was about 0.1 µm. The calcination was conducted at 773 K to remove the organic template. This membrane has a good stability at high temperature and in organic solvent. The membrane structure was identified by X-ray diffraction (XRD). The permeation of some pure gases was carried out to detect pinhole or cracking by studying mass transfer mechanism in the membrane. The pervaporation performance of as-synthesized membrane showed good results. This process was able to produce fuel grade bioethanol (99.2%) with the separation factor about 14.

Performance Characteristics of Bipolar Zn/MCM-41/ MnO2 Cell

We investigate Zn/MnO2 Leclanché cell employing inorganic MCM-41 membrane separator. MCM-41 membrane is developed onto zinc anode substrate from dip coating procedure, performed at room temperature. The parent solution for synthesis consisted of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB) as the organic template, sodium hydroxide, deionized wateSubscript textr, ethanol and tetraethylorthosilicate (TEOS). Zn/MCM-41/MnO2 cell, about the size of R2025 coin cell, is fabricated both in monopolar and bipolar designs. Bipolar cell configuration enhances the cell performance markedly. The cell demonstrates volumetric energy density - 42 Wh/l for bipolar design and 12 Wh/l for monopolar design, rated at continuous current drain of 1 mA.

Evaluation of Porous Electrode Properties Using Metal-Air Electrochemical System

This work explores the use of metal-air electrochemical system to evaluate porous electrode properties i.e. specific surface area and pore volume density. Porous zinc electrodes are prepared from an acidic, chloride electrolytic bath of varying supporting electrolyte (NH4Cl) formulation to produce electrodeposits of distinctive properties. Nitrogen physisorption at 77 K is utilized to evaluate the specific surface area and pore volume density of the electrodes. The zinc electrodeposits prepared from all electrolytic bath formulations are then assembled into zinc-air cells as the anodic electrode and characterized according to their limiting current density and discharge capacity. It is found that the variation in limiting current density matches that of BET surface area and the trend for discharge capacity follows that of pore volume density.

High energy density zinc–air microbattery utilising inorganic MCM-41 membrane

Abstract An ultrathin, high energy density zinc–air cell has been developed for potential application in microsystems. The key design feature is the utilisation of an inorganic MCM-41 membrane material with three-in-one functional elements. It serves as an insulating layer between the electrodes, as ionic exchange channels and as an electrolyte reservoir matrix. As a result, a feasible, compact cell design with high discharge capability has been demonstrated. The MCM-41 material consists of a hexagonally ordered, nanopore structure. It possesses attractive features of large surface area and pore volume, narrow pore size distribution, tunable pore size, adjustable hydrophobicity and very good thermal stability. The Zn/MCM-41/air cell measuring 1 cm2 area and ∼300 μm thick is able to deliver a maximum discharge current of 30 mA and possesses an optimum capacity of 35 mAh.