Biological, chemical and mathematical sciences

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Browsing Biological, chemical and mathematical sciences by Subject "Adsorption—Materials"

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    Adsorption of lead (II) from aqueous solution using nano-papaya peel
    (Universiti Teknologi Malaysia, 2017) Abbaszadeh, Sahar
    The presence of toxic heavy metals like lead (Pb(II)) in water resources due to industrialization is known to be a major environmental concern in many communities. Agrowaste has been the focus of studies as a reliable source of sustainable adsorbents for heavy metal removal from aqueous solutions. In this study, papaya peel has been introduced as a new source of agro-waste. The high annual papaya production in Malaysia potentially provides a good base to use its waste to develop an inexpensive adsorbent. Most of previous studies only consider the raw or carbon-active form of bioadsorbents. The present study aims to develop potential adsorption media for the removal of Pb(II) from contaminated water. While raw and carbon-activated adsorbents from papaya peel agro-waste are considered, a new nano adsorbent has been developed and evaluated in this research. The equilibrium sorptions of Pb(II) from an aqueous solution using synthesized adsorbents of activated carbon papaya peel (AC-PP) and nano-papaya peel (Nano-PP) were investigated. The synthesized adsorbents were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, field emission scanning electron microscopy, x-ray diffractometery and x-ray photoelectron spectroscopy. The batch experiments were carried out considering various Pb(II) concentrations of 10, 20, 50, 100, 200, and 400 mg/L, by changing variables of pH, adsorbent dosage, initial metal concentration, and temperature and contact time. The removal efficiency of the adsorbed amount of metal ions was considered relative to the equilibrium parameters. Desorption and regeneration studies were additionally conducted to evaluate reusability. The developed adsorbents showed excellent performance. Pb(II) was removed after 2 h of agitation, reaching optimal removal percentages of 82.6% using AC-PP (100 mg dosage) and 99.39 % using Nano-PP (50 mg dosage) after 3 h, at pH=5, in ambient condition. Equilibrium adsorption isotherms and kinetics were reviewed using the different isotherm models of Langmuir, Freundlich, and Temkin and kinetic models of the pseudo-first order, pseudo-second order, and intra-particle diffusion. The adsorption processes of Pb(II) onto Nano-PP and AC-PP were better described by the Langmuir isotherm model indicating monolayer Pb(II) adsorption onto the surface of the developed adsorbents and the adsorption kinetics was well fitted with the pseudo second-order kinetic model. Additionally, thermodynamic results confirmed the spontaneous adsorption processes with exothermic and endothermic nature onto surface of AC-PP and Nano-PP, respectively. The results obtained, especially for Nano-PP, confirm the capability of papaya peel adsorbents as a new, low-cost, efficient and environmentally friendly alternative for Pb(II) removal from contaminated water.
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    Polyethersulfone mixed matrix membrane containing imprinted zeolite for cresol removal in hemodialysis application
    (Universiti Teknologi Malaysia, 2020) Raharjo, Yanuardi
    The adequacy of uremic toxins removal on hemodialysis treatment is essential to be achieved for kidney failure disease patient, as poor removal leads to heart failure, hypertension, and stroke. The combination of adsorption and diffusion process has become very advantageous for hemodialysis membrane. By this mechanism, the urea as water soluble uremic toxins (WSUT) and p-cresol as protein-bounded uremic toxins (PBUT) could be removed at one time. Therefore, this study aimed to develop the novel imprinted zeolite by p-cresol (IZC) then incorporated into polyethersulfone (PES) and poly(vinyl pyrollidone) (PVP) to produce hollow fiber mixed matrix membrane (HF-MMM). IZC was synthesized from sodium aluminate, NaOH, H2O and SiO2 through aging and hydrothermal process with an initial composition of 10SiO2:Al2O3:4Na2O:180H2O by using imprinting technology and p-cresol as a template. Based on the properties and performance achieved, IZC could increase the selectivity to adsorb p-cresol 4.30 times greater compared to synthesized Zeolite Y (ZeoY-S). Adsorption study proved that IZC could adsorb p-cresol 2.5 and 3.5 times higher than ZeoY-S and commercialized zeolite Y (ZeoY-C), respectively. This is because the pore size of IZC had been successfully printed to p-cresol. The Brunauer-Emmet-Teller and transmission electron microscopy characterization proved that imprinting process was successfully applied. The investigation by isotherm and kinetics models showed that IZC was sensitive to attract the adsorbate, classifying it as having a strong adsorption behavior. Accordingly, the IZC is very promising to be applied as adsorbent in hemodialysis treatment. In the second phase, IZC as p-cresol’s adsorbent was incorporated into PES-based polymeric membrane with small addition of PVP to produce HF-MMM by using dry/wet spinning process. The effect of air gap distance between spinneret and coagulant bath and percentage loading for PES, PVP, and IZC were studied and optimized to obtain the best performance of HF-MMM. The 40 cm of air gap distance, 16 wt.% of PES, 2 wt.% of PVP, and 1 wt.% of IZC loading were able to produce superior hemodialysis membrane. These optimized parameters showed sufficient uremic toxins removal i.e. 60.74% of urea, 52.35% of p-cresol in phosphate buffer saline solution and 66.29% of p-cresol in bovine serum albumin solution for 4 hours permeation by using dialysis system. These HF-MMMs also achieved pure water flux of 67.57 Lm-2h-1bar-1 and bovine serum albumin rejection of 95.05%. Therefore, this membrane has been proven to be able to clean up WSUT and PBUT through an one-step process. Moreover, as compared neat PES membrane, MMM was able to remove p-cresol 186.22 times higher. Then, capability of IZC to adsorb p-cresol decreased to around 69% by changing the form of adsorbent from powder to composite in the membrane. By leaching study, it was obtained that percentage of zeolite leaching was less than 1 mgL-1 and categorized safe. In the final phase of the study, the HF-MMM developed was evaluated in terms of biocompatibility test, that is hemocompatiblity by using protein adsorption, platetels adhesion, blood clotting time test, activated partial thromboplastin time, prothrombin time, and cytotoxicity evaluation by using 3-(4,5-dimethylthiazol-2yl)-5(3-carboxymethoxy phenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTT assays). From the biocompatibility evaluation HF-MMM was observed to possess less protein adsorption, less activated state of the adhered platelets, non-toxic quality for red blood cells, and can prolong the clotting time and percentage of viability for more than 60%. These results proved that HF-MMM developed is safe for hemodialysis application.
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    The application of lattice gas automata for simulating polymer injection porous media
    (Universiti Teknologi Malaysia, 2006) Fathaddin, Muhammad Taufiq
    The simulation of polymer displacement in a reservoir is one of the important techniques in petroleum engineering that is used to predict the performance of oil production. Modeling of polymer flow through a porous medium is often derived by a macroscopic scale approach. In order to gain better insight of the polymer flow, a pore scale (mesoscale) model is applied in this thesis to determine the macroscopic properties. The objectives of this research are to develop the Frisch-Hasslacher-Pomeau (FHP) III models of lattice gas automata to simulate microscopic polymer and oil flow for the study of macroscopic properties of adsorption, gelation and polymer displacement phenomena. In the single-phase flow simulation, collision rules of interactions between polymer and solid material for adsorption and gelation processes were proposed. Correlations between various macroscopic properties such as polymer concentration, porosity, surface length, pore width were obtained. In general, the lattice gas automata simulations were in good agreement with previous studies, where the differences between them were between 2.0% to 17.4%. In the two-phase flow simulation, the displacement mechanism for various mobility ratio and adsorption rate was estimated. The change of saturation in dead-end pores during the displacement was analyzed. The results of the two-phase flow simulations were in good agreement with those of laboratory experiments, where differences of all parameters were between 3.1% to 18.4%. The computation time is a crucial factor influencing the feasibility of a mesoscale model application in simulating large porous media. Due to the nature of lattice gas automata, the simulation can run using parallel computers effectively. The use of parallel computers is able to reduce the computation time problem. In this thesis, a parallel computation technique has been proposed to run the lattice gas automata simulation. A cluster system and standalone computers were used to simulate communicating and non-communicating flow in porous media, respectively. The results of the parallel simulations were in good agreement with those of single simulations, where maximum difference of all parameters was 3.93%. The computation time was reduced by a factor that ranged from 1.9083 to 14.3411.