Ahmad N. Hakim

Combined ultrafiltration-electrodeionization technique for production of high purity water

Electrodeionization (EDI) is the most common method to produce high purity water used for boiler feed water, microelectronic, and pharmaceutical industries. Commonly, EDI is combined with reverse osmosis (RO) to meet the requirement of EDI feed water, with hardness less than 1 ppm. However, RO requires a relatively high operating pressure and ultrafiltration (UF) as pretreatment which results in high energy consumption and high complexity in piping and instrumentation. In this work, UF was used as the sole pretreatment of EDI to produce high purity water. Tap water with conductivity 248 μS/cm was fed to UF-EDI system. The UF-EDI system showed good performance with ion removal more than 99.4% and produced water with low conductivity from 0.2 to 1 μS/cm and total organic compounds less than 0.3 ppm. Generally, product conductivity decreased with the increase of current density of EDI and the decrease of feed velocity and UF pressure. The energy consumption for UF-EDI system in this work was 0.89-2.36 kWh/m3. These results proved that UF-EDI system meets the standards of high purity water for pharmaceutical and boiler feed water with lower investment and energy consumption than RO-EDI system.

The role of ion-exchange membrane in energy conversion

Ion-exchange membrane (IEM) may play an important role in the future of electrical energy generation which is considered as renewable and clean energy. Fell cell (FC) is one of the promising technologies for solving energy issues in the future owing to the interesting features such as high electrical efficiency, low emissions, low noise level, and modularity. IEM-based processes, such as microbial fuel cell (MFC) and reverse electrodialysis (RED) may be combined with water or wastewater treatment into an integrated system. By using the integrated system, water and energy could be produced simultaneously. The IEM-based processes can be used for direct electricity generation or long term energy storage such as by harnessing surplus electricity from an existing renewable energy system to be converted into hydrogen gas via electrolysis or stored into chemical energy via redox flow battery (RFB). In this paper, recent development and applications of IEM-based processes in energy conversion are reviewed. In add...

The Bubble Gas Transport Method

Abstract Pore size and pore size distribution are important parameters used to determine characteristics and performances of porous membranes. There are several methods which have been developed for determining these properties. Bubble gas transport, which is also called bubble point, is one of the standard methods that have been frequently used for pore size estimation of many commercial membranes due to its simplicity and convenience. However, this method has a limitation in determining pore size distribution. The combination of the bubble gas transport method with gas permeation can be a useful method for characterizing pore size distribution. In this book section, the principles, experimental setup and procedure, and some critical aspects to be considered in the bubble gas transport method, as well as its extended method, are presented.

Study on the influence of applied voltage and feed concentration on the performance of electrodeionization in nickel recovery from electroplating wastewater

Wastewaters from electroplating industries are usually contaminated with nickel up to 1000 mg/L. According to environmental regulations worldwide, nickel concentration on wastewaters must be controlled to an acceptable level before being discharged to the environment. This paper offers an alternative way to develop an efficient effluent-free technology to reduce the nickel content of rinse water so that the treated water could be recycled for rinsing and subsequently to workout methodology to recover nickel by electrodeionization (EDI). Electrical voltage and initial nickel concentration were varied to study the effect of the parameters. Results showed that EDI could remove nickel effectively which gives an outstanding result in terms of product quality. Nickel concentration on diluate chamber decreased up to 99% after 60 and 180 minutes for nickel concentration of 300 and 1000 mg/L, respectively. Meanwhile, the increase of electrical voltage led to faster nickel removal.

Determination of thermodynamic properties of polysulfone/PEG membrane solutions based on Flory-Huggins model

Flory-Huggins (F-H) model was used to study thermodynamic properties of polysulfone-based membrane solution that consists of water, dimethylacetamide (DMAC), polysulfone (PSf), and polyethylene glycol (PEG400). The thermodynamic properties of membrane solution were examined based on equilibrium composition in a ternary diagram of the membrane system, which known as binodal curve. The binary interaction parameters of each component in F-H model were predicted based on cloud point experiment at various PSf and PEG400 concentrations and used to calculate the binodal curve in ternary diagram. It was obtained that the binary interaction parameters in the membrane solution are: X13 (water–PSf) = 6.76, g14 (water–PEG400) = 0.51, g23 (DMAc–PSf) = 0.46, g24 (DMAc–PEG400) = 0.46, and g34 (PSf–PEG400) = −0.53. Based on the thermodynamic analysis in the ternary diagram, low solubility of membrane solution was achieved when 20 wt% of PSf was blended with a high concentration of PEG400 (20–30%). It means that the membr...

Nano-silica/polysulfone asymmetric mixed-matrix membranes (MMMs) with high CO2 permeance in the application of CO2/N2 separation

ABSTRACT Nano-sized silica/polysulfone (PSf) flat sheet asymmetric MMMs with high CO2 permeance for CO2/N2 separation were fabricated by dry/wet phase inversion method using N, N-dimethylacetamide (DMAc) and tetrahydrofuran (THF) as solvents and ethanol as additives. The results indicated that the addition of nano-silica on the polymer matrix resulted on reduced membrane performance due to void formation and particle agglomeration. Optimum membrane performance was obtained at the following fabrication parameters: 22 wt.% PSf, 31.8 wt.% DMAc, 31.8 wt.% THF, 14.4 wt.% ethanol, 20 s evaporation time, and 0 wt.% silica loading, with CO2/N2 selectivity of 15.6 and CO2 permeance of 14.2 GPU. Graphical Abstract