Nanocomposite ultrafiltration membranes incorporated with zeolite and carbon nanotubes for enhanced water separation

The objective of this work is to develop a new class of nanocomposite ultrafiltration (UF) membranes with excellent solute rejection rate and superior water flux using zeolitic imidazolate framework-8 (ZIF-8) and multi-walled carbon nanotubes (MWCNTs). The effect of ZIF-8 and MWCNTs loadings on the properties of polyvinyldifluoride (PVDF)-based membrane were investigated by introducing respective nanomaterial into the polymer dope solution. Prior to filtration tests, all the membranes were characterized using several important analytical instruments, i.e., SEM-EDX and contact angle analyzer. The addition of the nanoparticles into the membrane matrix has found to increase the membrane pore size and improve its hydrophilicity compared to the pristine membrane. The separation performance of membranes was determined with respect to pure water flux and rejections against bovine serum albumin (BSA) and humic acid (HA).The experimental findings indicated that the nanocomposite membranes in general demonstrated higher permeation flux and solute rejection compared to the pristine membrane and the use of ZIF-8 was reported to be better than that of MWCNTs in preparing nanocomposite UF membranes owing to its better flux and high percentage of solute rejection

Development of Copper-Aluminum Layered Double Hydroxide in Thin Film Nanocomposite Nanofiltration Membrane for Water Purification Process

This study aims to fabricate a thin film composite (TFC) membrane, modified with copper-aluminium layered double hydroxide (LDH) nanofillers via interfacial polymerization technique for nanofiltration (NF) processes. It was found that Cu-Al LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape and positive surface charge. The study revealed that TFN membrane exhibits a relatively smooth surface and a less nodular structure compared to pristine TFC membrane. The contact angle of TFN progressively decreased from 54.1° to 37.25°, indicating enhancement in surface hydrophilicity. Moreover, the incorporation of LDH nanofillers resulted in a less negative membrane as compared to the pristine TFC membrane. The best NF performance was achieved by TFN2 membrane with 0.1° of Cu-Al LDH loading and a water flux of 7.01 Lm-2h-1.bar. The addition of Cu-Al LDH resulted in excellent single salt rejections of Na2SO4 (96.8%), MgCl2 (95.6%), MgSO4 (95.4%), and NaCl (60.8%). The improvement in anti-fouling properties of resultant TFN membranes can be observed from the increments of pure water flux recovery and normalized water flux by 14% and 25% respectively. The findings indicated that Cu-Al LDH is a promising material in tailoring membrane surface properties and fouling resistance. The modification of the LDH-filled TFN membrane shows another alternative to fabricating a high-performance composite membrane, especially for water softening and partial desalination process

Development of copper-aluminum layered double hydroxide in thin film nanocomposite nanofiltration membrane for water purification process

This study aims to fabricate a thin film composite (TFC) membrane, modified with copper-aluminium layered double hydroxide (LDH) nanofillers via interfacial polymerization technique for nanofiltration (NF) processes. It was found that Cu-Al LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape and positive surface charge. The study revealed that TFN membrane exhibits a relatively smooth surface and a less nodular structure compared to pristine TFC membrane. The contact angle of TFN progressively decreased from 54.1° to 37.25°, indicating enhancement in surface hydrophilicity. Moreover, the incorporation of LDH nanofillers resulted in a less negative membrane as compared to the pristine TFC membrane. The best NF performance was achieved by TFN2 membrane with 0.1° of Cu-Al LDH loading and a water flux of 7.01 Lm-2h-1.bar. The addition of Cu-Al LDH resulted in excellent single salt rejections of Na2SO4 (96.8%), MgCl2 (95.6%), MgSO4 (95.4%), and NaCl (60.8%). The improvement in anti-fouling properties of resultant TFN membranes can be observed from the increments of pure water flux recovery and normalized water flux by 14% and 25% respectively. The findings indicated that Cu-Al LDH is a promising material in tailoring membrane surface properties and fouling resistance. The modification of the LDH-filled TFN membrane shows another alternative to fabricating a high-performance composite membrane, especially for water softening and partial desalination process

Catalytic chelation technique for the removal of toxic and heavy metals from green mussel, perna viridis

Malaysian mussels can be contaminated with toxic and heavy metals which are cumulative poison through long term ingestion. Currently, no commercially viable technology has been developed for the removal of these toxic and heavy metals from contaminated mussels. Therefore, the purpose of the study is to develop method that safely removes metals from contaminated mussels so as to comply with the permissible limit set by the Malaysian Food Regulations (1985) and Commission Regulation of EU (2006) for human consumption. The removal of toxic and heavy metals in mussels by catalytic chelation method was studied using three types of chelating agent salts, namely trisodium citrate, disodium oxalate and sodium acetate. Three types of catalysts supported on Al2O3, namely MgO, BaO and CaO were used. The preliminary treatment conditions was carried out using trisodium citrate at a concentration of 500 mg/L, one hour treatment time, treatment temperature of 32.5±0.5oC and pH 7-8. All metals analysis were carried out using inductively coupled plasma mass spectrometry technique. The study shows that female mussel accumulates higher concentration of toxic and heavy metals as compared to male mussel. The results indicated that sodium acetate gave the highest percentage removal of toxic and heavy metals (As 59.50%, Pb 88.57%, Cd 68.01% and Ni 79.67%) followed by disodium oxalate (As 46.89%, Pb 85.46%, Cd 60.41% and Ni 47.80%) and trisodium citrate (As 38.13%, Pb 68.90%, Cd 70.49% and Ni 36.92%). Thus, all treatment conditions were optimized according to sodium acetate in subsequent study. The presence of catalysts improved toxic and heavy metals removal in mussels. Among the three catalysts studied, CaO catalyst gave the highest percentage removal (As 46.89%, Pb 85.46%, Cd 60.41% and Ni 47.80%) followed by BaO and MgO at an optimum calcination temperature of 1000oC. XRD analysis revealed the active sites were due to the presence of orthorhombic Al2O3, monoclinic CaAl4O7/CaO.2Al2O3 and cubic Ca12Al14O33 species. Meanwhile, FESEM analysis displayed the formation of homogeneous particles with undefined shape, aggregated and agglomerated on the catalyst surface. BET surface area study gave a surface area of 33.22 m2/g. EDX analysis showed a weight percentage of O=57.43%; Al=35.93%; Ca=6.64%. FTIR analysis showed total removal of metal precursor by CaO/Al2O3 catalyst at 1000oC calcinations temperature

Novel environmentally friendly catalytic oxidation approaches on elemental mercury removal from carbon steel surface

To date, technology for the removal of elementary mercury adsorbed on carbon steel surfaces with very minimum iron (Fe) leaching is apparently missing. In this study, the oxidation reaction of mono-peroxyacetic acid (PAA) was used in the presence of Ru/Mn/Al2O3 catalyst to enhance the treatment removal. The obtained results revealed that the PAA alone could reduce 91% of Hg° removal in 3 h. Interestingly, with the presence of Ru/Mn/Al2O3 catalyst calcined at 1000°C, the PAA managed to remove almost 99% of Hg° at the same treatment time with the lowest Fe leaching of 17 ppm

Chelation technique for the removal of heavy metals (As, Pb, Cd and Ni) from green mussel, Perna viridis

Present research was carried out to study the efficiency of chelation method to remove heavy metals like arsenic (As), lead (Pb), cadmium (Cd) and nickel (Ni) from P. viridis. Chelation method was studied using three types of chelating agents, namely trisodium citrate, disodium oxalate and sodium acetate. Metals concentrations were analysed using ICP-MS technique. Results showed that the sodium acetate gave the highest percentage removal of heavy metals (As 59.50%, Pb 88.57%, Cd 68.01% and Ni 79.67%) followed by disodium oxalate (As 46.89%, Pb 85.46%, Cd 60.41% and Ni 47.80%) and trisodium citrate (As 38.13%, Pb 68.90%, Cd 70.49% and Ni 36.92%). The findings showed that sodium acetate was able to chelate and remove all the studied heavy metals to levels below the permissible limit set forth by Malaysian Food Regulations (1985) and EU Commission Regulation (2006)

Development of thin film nanocomposite embedded with graphene oxide for MgSo4 removal

Thin film nanocomposite (TFN) membrane with graphene oxide (GO) embedded into the polyamide (PA) selective top layer has been developed for salt removal. 0.1 wt% of GO were dispersed in the trimesoyl chloride (TMC) organic solution and incorporated into the PA layer during interfacial polymerization with piperazine. The fabricated TFN membrane was characterized in terms of the membrane morphological structure and surface hydrophilicity. The divalent magnesium sulfate (MgSO4) salt removal performance of the TFN was evaluated and compared with the thin film composite (TFC) counterpart. The surface morphology of the TFN membranes was altered and the surface hydrophilicity was increased with the presence of GO. The incorporation of GO has improved the permeate water flux, in which maximum improvement of 140% compared to that of TFC has been obtained, without sacrificing much on the salt rejection properties. Although further investigation is required, this study has experimentally verified the potential application of GO to heighten the salt separation performance of TFN membranes

The Modification of PVDF Membrane via Crosslinking with Chitosan and Glutaraldehyde as the Crosslinking Agent

Poly(vinylidene fluoride) (PVDF) has outstanding properties such as high thermal stability, resistance to acid solvents and good mechanical strength. Due to its properties, PVDF is widely used as a membrane matrix. However, PVDF membrane is hydrophobic properties, so as for specific applications, the surface of membrane needs to be modified to become hydrophilic. This research aims to modify PVDF membrane surface with chitosan and glutaraldehyde as a crosslinker agent. The FTIR spectra showed that the modified membrane has a peak at 1655 cm-1, indicating the imine group (–N=C)- that was formed due to the crosslink between amine group from chitosan and aldehyde group from glutaraldehyde. Results showed that the contact angle of the modified membrane decreases to 77.22° indicated that the membrane hydrophilic properties ( 90°). The results of porosity, Ɛ (%) for unmodified PVDF membrane was 55.39%, while the modified PVDF membrane has a porosity of 81.99%. Similarly, by modifying the PVDF membrane, pure water flux increased from 0.9867 L/m2h to 1.1253 L/m2h. The enhancement of porosity and pure water flux for the modified PVDF membrane was due to the improved surface hydrophilicity of PVDF membrane

Zeolite zsm5-filled pvdf hollow fiber mixed matrix membranes for efficient carbon dioxide removal via membrane contactor

ZSM5 zeolite-filled PVDF mixed matrix membranes were wet spun and used for CO2 absorption in contactor system. The properties of ZSM5 were analytically characterized. SEM images revealed the fully asymmetric structure of membranes, in which the creation of finger-like macrovoids was promoted with the increasing filler loading. A significant increase in gas permeance was observed, which was associated with the porosity increase of the membrane surface despite the decrease in surface pore size. The surface roughness, wettabilite resistance and mechanical stability of membranes were also considerably improved by filler loading. CO2 absorption test with water revealed higher CO2 flux of MMMs than that of the plain membrane. Peak absorption flux of 5.80 × 10-3 molm-2 s-1 was achieved at liquid velocity of 1.2 ms -1 for 5 wt%ZSM5/PVDF membrane(MZ5), which was nearly 177% higher than neat PVDF and also surpassed that of several commercial and in - house made membranes. The mass transfer resistance of the MMMs was also considerably lower than that of PVDF

Enhanced desalination of polyamide thin film nanocomposite incorporated with acid treated multiwalled carbon nanotube-titania nanotube hybrid

Polyamide (PA) thin film nanocomposite (TFN) membrane incorporated with multiwalled carbon nanotubes-titania nanotube (MWCNT-TNT) hybrid was successfully fabricated. The hybrid was introduced to the PA selective layer during the interfacial polymerization (IP) of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) monomers over porous commercial polysulfone (PS) ultrafiltration support. The resultant TFN was characterized and applied for desalination. The results revealed that the acid treated MWCNT-TNT, which act as filler in the PA membrane, improved the surface properties of the membrane in term of surface charge, surface roughness and contact angle. Consequently, the water permeability increased significantly without compromising the salt rejection performance. The highest water permeability of 0.74 L/m2 h bar was achieved for the TFN membrane containing 0.05 wt% acid treated MWCNT-TNT, which is approximately 57.45% than that of the neat PA membrane. The NaCl and Na2SO4 rejection of this membrane was 97.97% and 98.07%, respectively that is almost similar to the neat membrane