Anita Kusuma Wardani

Preparation of Superhydrophobic Polypropylene Membrane Using Dip-Coating Method: The Effects of Solution and Process Parameters

ABSTRACT Superhydrophobic polypropylene hollow fiber membranes were prepared through two-step dip-coating process. The effects of solution and process parameters were investigated. It was found that polymer solution concentration and temperature were crucial parameters to obtain homogeneous coating. High hydrophobicity could be achieved by controlling the polymer solution concentration and drying temperature. Using methyl ethyl ketone as nonsolvent, the membrane surface roughness was increased, resulting in superhydrophobicity with high contact angle of 151.3°. The modified membrane still exhibited lower flux than unmodified membrane in water–oil separation due to porosity decrease. However, their water rejections were comparable. GRAPHICAL ABSTRACT

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.

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.

Recent progress and challenges in membrane-based O2/N2 separation

Abstract Compared with current conventional technologies, oxygen/nitrogen (O2/N2) separation using membrane offers numerous advantages, especially in terms of energy consumption, footprint, and capital cost. However, low product purity still becomes the major challenge for commercialization of membrane-based technologies. Therefore, numerous studies on membrane development have been conducted to improve both membrane properties and separation performance. Various materials have been developed to obtain membranes with high O2 permeability and high O2/N2 selectivity, including polymer, inorganic, and polymer-inorganic composite materials. The results showed that most of the polymer membranes are suitable for production of low to moderate purity O2 and for production of high-purity N2. Meanwhile, perovskite membrane can be used to produce a high-purity oxygen. Furthermore, the developments of O2/N2 separation using membrane broaden the applications of oxygen enrichment for oxy-combustion, gasification, desulfurization, and intensification of air oxidation reactions, while nitrogen enrichment is also important for manufacturing pressure-sensitive adhesive and storing and handling free-radical polymerization monomers.

Review of hydrophilic PP membrane for organic waste removal

The acceleration of industrialization in developing countries has given an impact of environmental pollution rapidly, such as contamination of groundwater with organic waste. To solve this problem, some membrane techniques have been performed to remove organic waste from water, such as membrane contactors, membrane bioreactors, and supported liquid membranes. Polypropylene (PP) membrane is one of the promising candidates for these membrane processes due to its chemical stability, low cost, good mechanical resistance, and being easily available. However, different processes require membranes with different surface properties. Hydrophobic PP membranes with excellent chemical stability can be directly used in membrane contactors, in which the organic phase wets the porous membrane and slightly excessive pressure applied to the other phase. On the other hand, hydrophilization of PP membrane is necessary for some other processes, such as for fouling reduction on membrane bioreactors due to organic matters depo...