Catalytic Recovery of Elemental Sulfur Using a Novel Catalytic Membrane Reactor at Room Temperature with a Layer of Dispersed Mo-Co/γ-Al₂O₃ Catalyst: Reaction Kinetics and Mass Transfer Study
Pages 28-39

Sujoy Bose, Rishiket Kundu and Chandan Das
DOI: http://dx.doi.org/10.6000/1929-6037.2017.06.01.3

Published: 07 April 2017

Abstract: The mass transfer rate of catalytic recovery of sulfur is investigated, enters through the catalyst-membrane interface (layer), accompanied by pseudo-first order irreversible reaction. Reaction kinetics is measured considering the system as a homogeneous system due to the consideration of mixed flow patterns of the reacting fluids, though the catalysis is a heterogeneous one. The multi-reactant mass transfer behaviour of the catalytic membrane reactor (CMR) is also studied on the basis of Maxwell-Stefan theory to understand the diffusion of reactants inside the membrane reactor. The mass transport behaviour and the performance of the fabricated CMR are strongly influenced by the reaction conditions, such as, reaction equilibrium constant (K_eq) and membrane properties, namely, membrane area and reactor volume. An intermediate value with asymptotic nature of K_eq as a function of time indicates appreciable performance of the catalytic membrane. On the other hand, the minimum value of k_ij indicates a negligible effect on mass transfer over the reactor performance.

Separation Enhancement of Mechanical Filters by Adding Negative Air Ions
Pages 132-139
Shinhao Yang, Yi-Chin Huang, Chin-Hsiang Luo and Chi-Yu Chuang

DOI: http://dx.doi.org/10.6000/1929-6037.2016.05.04.2

Published: 08 February 2017

Abstract: The purpose of this work is to combine negative air ions (NAIs)and mechanical filters for removal of indoor suspended particulates. Various factors, including aerosol size (0.05-0.45 μm), face velocity (10 and 20 cm/s), species of aerosol (potassium chloride and dioctyl phthalate), relative humidity (30% and 70%), and concentrations of NAIs (2 ´ 10⁴, 1 ´ 10⁵, and 2 ´ 10⁵ NAIs/cm³) were considered to evaluate their effects on the aerosol collection characteristics of filters.Results show that the aerosol penetration through the mechanical filter is higher than that through the mechanical filters cooperated with NAIs. This finding implies that the aerosol removal efficiency of mechanical filters can be improved by NAIs. Furthermore, the aerosol penetration through the mechanical filters increased with the aerosol size when NAIs were added. That is due to that the aerosol is easier to be charged when its size gets larger.The results also indicate the aerosol penetration decreased with the NAIs concentration increased. Reversely, aerosol penetration through the mechanical filters increased with the face velocity under the influence of NAIs. The aerosol penetration through the filter with NAIs was no affected with relative humidity. Finally, The penetration through the filter with NAIs against solid aerosol was lower than that against liquid aerosol.

Zeolite A-Carbon Membranes: Possibilities in H₂ Purification and how to Overcome their Shortcomings
Pages 121-131
Francisco J. Varela-Gandía, Dolores Lozano-Castelló, Diego Cazorla-Amorós and Ángel Berenguer-Murcia

DOI: http://dx.doi.org/10.6000/1929-6037.2016.05.04.1

Published: 08 February 2017

Abstract: This work describes the modification of zeolite Na-LTA membranes supported on macroporous carbon materials, prepared by a combination of secondary hydrothermal treatment followed by different alternative post-synthesis procedures, which aim at improving the permeance properties of the as-synthesized Na-LTA membranes with a simulated reformer mixture (H₂, CO, CO₂ and H₂O) towards their use in a hydrogen purification device.These post-synthetic treatments include the deposition of a thin layer of amorphous silica formed by the hydrolysis of a silicon alcoxide, the coating with a thin metallic film by electroless plating, and the deposition of noble metal nanoparticles. Our results indicate that some of these treatments, which may be performed very quickly compared to other treatments which are generally used in order to improve the quality of the membranes, result in membranes which may effectively separate H₂ from CO under simulated reformer conditions. Considering the simple approach employed in some of the cases described in this study, the potential benefits should be considered highly interesting in fields such as membrane recovery and membrane selectivity control.

Response Surface Optimization of Electro-Spun Polyvinyl Alcohol Nano-Fiber Membrane Process Parameters and its Characterization
Pages 140-156
Kibrom Alebel Gebru and Chandan Das

DOI: http://dx.doi.org/10.6000/1929-6037.2016.05.04.3

Published: 08 February 2017

Abstract: An empirical exploration into the effects of time duration, voltage supply, concentration and flow rate on the membrane average fiber diameter and surface pore size distribution were done using response surface methodology (RSM) based on central compact design (CCD). The average fiber diameter and average surface pore diameter of the membrane (i.e. 110 nm and 130 nm, respectively) were obtained at optimum input parameters of 45 min, 10 wt. %, 12 kV and 1.0 mL/h for time duration, concentration, voltage supply, and flow rate, respectively. The optimization study shows that the predicted versus actual values of both membrane fiber diameter and surface pore diameter are at R² = 0.96. In addition, the effect of glutaraldehyde on membrane crosslinking was also assessed for further studies. The results from FESEM images of the fabricated PVA nanofiber membranes using the optimized parameters revealed that the membranes showed smooth morphological structures without formation of beads. The thermo gravimetric analysis (TGA) results displayed an improvement in thermal stability after membrane crosslinking. From this study we have observed that the membrane average fiber diameter and surface pore diameter can be controlled by varying the electro-spinning parameters and can be utilized for wastewater treatment application.