Effect of graphene oxide (GO) and polyvinylpyrollidone (PVP) additives on the hydrophilicity of composite polyethersulfone (PES) membrane

Membrane based separation system is considered as a promising technology to purify water, owing to its simplicity and efficiency in operation. However, the application is limited by membrane fouling, which can lead to the declination of water flux and premature failure of membrane. The fouling can be controlled through membrane surface modification by blending hydrophilic materials during the casting solution preparation. Polyethersulfone (PES) membrane is naturally hydrophobic due to lack of oxygen functional group, which limits its application in the filtration of water. Therefore, modification of PES-based membranes is required. In this work, modification of the PES membrane was carried out by incorporating carbon-based nanomaterials (graphene oxide (GO)) and a well-known organic polymer (polyvinylpyrrolidone (PVP)). The effect of each additive toward the hydrophilicity of composite PES membrane was then investigated. GO was synthesized using modified Hummers method due to its simpler and shorter process. Each additive was added during the casting solution preparation and the amount added was varied from 0.5 to 1.0 wt%. The resultant composite PES membranes were characterized using XRD, FTIR and TGA prior to hydrophilicity and pure water flux (PWF) measurement. It was observed that the additives (PVP and GO) have significantly affected the membranes hydrophilicity, resulting in lower contact angle and higher pure water flux. The highest value of PWF (230 L/m2.h) with lowest contact angle (42 °) were observed for PES-1.0GOPVP membrane due to high amount of GO and PVP. Improved PWF performance of composite PES-1.0GOPVP membrane was attributed to the better dispersibility of the PVP and GO and increased surface hydrophilicity of the modified composite membranes. This study indicated that PVP and GO are effective modifiers to enhance the performance of PES membrane

Adsorption of anionic surfactant on surface of reservoir minerals in alkaline-surfactant-polymer system

Alkaline-surfactant-polymer (ASP) flooding is significant to the oil and gas industry due to synergistic interaction between alkaline, surfactant and polymer. However, chemical losses due to adsorptions of surfactant and polymer on the rock surface could lead to inefficiency of the process. There are also significant uncertainties on adsorption mechanism when surfactant is flooded with presence of alkaline and polymer. This study highlights the static adsorption tests using anionic sodium dodecyl sulphate (SDS), hydrolysed polyacrylamide (HPAM) and sodium carbonate (Na2CO3) as the surfactant, polymer and alkaline, respectively. Sand particles and kaolinite clay were used as the reservoir minerals. The adsorption tests were conducted at various surfactant concentrations ranging from 50 to 2000 ppm. Sodium chloride (NaCl) concentration was investigated from 0 to 2 wt.%, while the local sand and kaolinite was mixed in surfactant solution at a fixed mass to volume ratio of 1:5. The static adsorption test was conducted by shaking the mixture samples and centrifugation before analysing the supernatant liquid using UV-Visible spectrophotometer. The results showed that the surfactant adsorption was higher on kaolinite compared to sand particle. The higher the salinity, the higher the adsorption of surfactant due to higher ionic strength. The adsorption of SDS surfactant on sand particles and kaolinite was lesser in ASP system compared to the presence of surfactant solution alone. Thus, it can be concluded that the presence of polymer and alkaline in ASP solution have great potential to reduce the surfactant adsorption on both sand particle and kaolinite

Energy integrated distillation columns sequence (EIDC) of 5-component alcohol mixture via driving force and thermal pinch analysis approach

Distillation column is a well-known unit operation to perform the intended separation task in chemical and petrochemical industries. However, the common issue for distillation column is the large energy requirement especially for multicomponent processes. Therefore, the sequence determination could be a key to solve the problem. This paper provides a methodology to produce energy integrated distillation columns sequence via driving force sequence approach. Then, it is supported by the thermal pinch analysis for further the energy saving in the process. The case study selected is distillation process of 5-component alcohol mixture. Based on the input data, two sequences for distillation columns namely direct sequence and driving force sequence were firstly simulated. Then, the resulting information such as target temperature, supply temperature and energy from condensers and reboilers have been extracted for thermal pinch analysis. Lastly, the energy requirements from the analysis (before and after pinch analysis) were compared for energy saving calculation. Based on the analysis results, the driving force sequence with pinch analysis successfully enhanced the 35% of the overall energy saving. Thus, it can be said that the driving force sequence and thermal pinch analysis approach namely energy integrated distillation columns sequence has a potential for further the energy saving of the distillation columns sequence for the selected case study

Energy Analysis and Remixing Effect of Thermal Coupling Petlyuk Column for Natural Gas Liquid (NGL) Fractionation Train

In this work, a non-conventional distillation sequence with thermal coupling (Petlyuk Column) was presented as a technique to perform the separation of the NGL consist of ethane, propane, butane or other higher alkanes. The improvements were investigated through the energy analysis and remixing effect. From the result obtained, it was found that the Petlyuk arrangement consumes less amount of energy and able to reduce the remixing effects as compared to the conventional column sequencing. The Petlyuk arrangement saved about 44.49% and 12.83% in terms of cooling and heating duty, respectively. The overall annual energy saving shown by this arrangement is 39.22%. This arrangement proved to be able to prevent the remixing effect occurrence that contributes to thermal and separation inefficiency. The desired separation efficiency also obtained by this arrangement as all the product specifications are met. The ability in avoiding remixing effect by the Petlyuk column permits a significant reduction in CO2 emission with an average of 29.43 % of each equipment involved. Hence, it can be concluded that the Petlyuk arrangement model is a better alternative to be implemented in the NGL fractionation train

In-Situ Catalytic Surface Modification of Micro-Structured La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) Oxygen Permeable Membrane Using Vacuum-Assisted technique

This paper aims at investigating the means to carry out in-situ surface modification of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) oxygen permeable membrane by using vacuum assisted technique. The unique structure of the LSCF hollow fibre membrane used in this study, which consists of an outer dense oxygen separation layer and conical-shaped microchannels open at the inner surface has allowed the membrane to be used as oxygen separation membrane and as a structured substrate for where catalyst can be deposited. A catalyst solution of similar material, LSCF was prepared using sol-gel technique. Effects of calcination temperature and heating rate were investigated using XRD and TGA to ensure pure perovskites structure of LSCF was obtained. It was found that a lower calcination temperature can be used to obtain pure perovskite phase if slower heating rate is used. The SEM photograph shows that the distribution of catalyst onto the membrane microchannels using in-situ deposition technique was strongly related to the viscosity of LSCF catalytic sol. Interestingly, it was found that the amount of catalyst deposited using viscous solution was slightly higher than the less viscous sol. This might be due to the difficulty of catalyst sol to infiltrate the membrane and as a result, thicker catalyst layer was observed at the lumen rather than onto the conical-shaped microchannels. Therefore, the viscosity of catalyst solution and calcination process should be precisely controlled to ensure homogeneous catalyst layer deposition. Analysis of the elemental composition will be studied in the future using energy dispersive X-ray Spectroscopy (EDX) to determine the elements deposited onto the membranes. Once the elemental analysis is confirmed, oxygen permeation analysis will be carried out

Evaluation of sound comfort in examination hall using acoustical environmental analyses

Acoustics environmental analyses were conducted in the unoccupied examination hall at Universiti Tun Hussein Onn Malaysia (UTHM), in order to determine the acoustical environment which reflects to sound comfort during sitting exam. The acoustic parameters that measured are background noise level, sound pressure level and reverberation time. The analysis result of untreated wall condition (without absorbent material) was revealed poor while treated wall condition (with absorbent material) revealed the improvement result. Installation of absorbent material on the wall and speakers rearrangement had reduced the highest background noise level of examination hall average reverberation times. A minor alteration at examination hall had contributed to better acoustic performance

Adsorption kinetics of methylene blue dyes onto magnetic graphene oxide

Adsorption is one of the most effective methods for the treatment of wastewater containing dyes owing to its low operating cost, simplicity of process design and smaller amounts of harmful substances. In this work, graphene oxide- magnetic iron oxide nanoparticles (GO-MNP) was synthesized using sonomechanical technique and used as effective adsorbent for synthetic methylene blue (MB) dye removal. Batch adsorption experiments were performed with the variation of initial MB dye concentration, pH solution, adsorbent dosage and contact time. The adsorbent showed significant removal efficiency around 99.6% for MB. It was found that the removal rate of MB dye in the solution was higher when higher pH, larger dosage of adsorbent in solution and longer contact time were used. A regenerative study was carried out and minor reduction in adsorption capacity of the regenerated GO-MNP was observed after 2 cycles. Analysis of adsorption equilibrium revealed that the data is well fitted with Langmuir and Freundlich adsorption isotherm model (R2 > 0.97), indicating multi layer adsorption of dye on the surface of adsorbent. In the case of adsorption kinetics, the GO-MNP adsorbent follows pseudo-second order kinetics model showing R2 > 0.999, whereas for pseudo-first order kinetics model, the value of R2 was significantly lower. The finding of the present work highlights simple fabrication of magnetic GO and its application as efficient and magnetically separable adsorbent for environmental clean-up