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Plastic waste poses a significant environmental threat. To address this issue and mitigate water pollution caused by heavy metals, this study repurposed HDPE plastic waste into functional membranes. To enhance the membrane's properties, HDPE was blended with EVA to improve hydrophilicity and flexibility, and then coated with PDMS to reduce pore size. These membranes were fabricated using a sustainable and cost-effective TIPS process with mineral oil as a solvent. Characterization techniques, including SEM, FTIR, EDX, contact angle measurement, AFM, and stress-strain analysis, were employed to investigate the morphological, chemical, and mechanical properties of the membranes. Zeta potential measurements were also conducted to assess the surface charge. The performance evaluation revealed that PDMS coating significantly increased the rejection of Ni(II) and Pb(II) ions (up to 63 % and 78 %, respectively), while EVA addition improved the pure water flux (from 16 to 44 L/(m2·h)). The membranes exhibited good performance over a range of pH, contact time, and metal ion concentrations. Additionally, the membranes demonstrated excellent cleaning efficiency with NaOCl and citric acid, maintaining high flux recovery and metal removal rates after multiple cycles. The study's findings highlight the potential of repurposing plastic waste into functional membranes for water treatment applications, contributing to a more sustainable and circular economy.

Cellulose nanofibrils (CNF) are promising renewable materials due to their high surface area, abundance, and ease of modification. This study explores the impact of source material on CNF properties for diverse applications like drug delivery and composites. CNF were prepared from corn cob (CC), bagasse (BG), waste wood (WW), and bacterial cellulose (BC) using TEMPO-mediated oxidation. Microcrystalline cellulose (MCC) was also oxidized (MCC-ox) for comparison. The transparency, chemical structure, crystallinity index, and surface charge of the resulting CNF were investigated. As a result, all CNF yields ranged from 25 % to 34 %. FT-IR analysis confirmed successful TEMPO oxidation by detecting carboxyl groups on all CNF surfaces. BC-derived CNF displayed the second-highest transparency after MCC. Surface charge analysis revealed the highest carboxyl content in MCC-ox (8828.39 mmol/kg), followed by CNF-BC (8438.84 mmol/kg), CNF-CC (7687.24 mmol/kg), CNF-WW (6720.43 mmol/kg), and CNF-BG (5505.61 mmol/kg). XRD analysis indicated the highest crystallinity index in MCC-ox (83.40 %) due to its high purity, followed by CNF-BC (82.52 %) likely due to its nanostructure and high purity, and CNF-CC (78.14 %) potentially due to the rigid and dense structure of corn cobs. These findings provide valuable insights into selecting CNF with the desired characteristics for various fields such as material science, nanotechnology, and biomedicine.

The demand for efficient and sustainable gas separation technologies is ever-increasing in various industries, including petrochemicals, natural gas processing, and carbon capture. Polymer-based membranes offer a promising solution due to their potential for high selectivity and energy efficiency. However, achieving optimal gas separation performance often requires overcoming the limitations of individual polymers through modifications such as polymer blending. In this study, PSf/P84 blended membranes with low P84 content were fabricated using the phase separation technique with a mixture of N-methyl-2-pyrrolidone and tetrahydrofuran as solvents. The effect of varying the mass ratio of PSf to P84 on membrane characteristics and gas separation performance was investigated. Characterization techniques included FTIR, XRD, SEM, TGA, Water Contact Angle (WCA) measurement, and mechanical property testing. Gas permeation tests were conducted with single gases at room temperature and 1 bar pressure. The results revealed that the addition of P84 increased membrane thickness, Young's modulus, and thermal stability, while decreasing d-spacing, dense layer thickness, hydrophilicity, tensile strength, and elongation. The Findex values, indicating the competence of the blended membranes compared to the ideal quality, demonstrated the positive impact of P84 addition on gas separation performance compared to pure PSf membranes. The optimal gas separation selectivity was achieved with the PSf/P84 1:0.025 blended membrane for H2/CH4 (11.28, 58 % increase), H2/CO2 (6.25, 193 % increase), and H2/N2 (5.25, 35 % increase). The highest N2/CH4 selectivity (6.29, 253 % increase) was observed with the 1:0.10 composition. Regarding commercially relevant separations based on the 2008 Robeson curve, the PSf/P84 1:0.20 blend showed promise for H2/CO2 separation, while the 1:0.05 and 1:0.10 blends were suitable for N2/CH4 separation.

High-density polyethylene (HDPE), a widely used polymer globally, notably found in plastic bags, presents an environmental concern due to its non-biodegradable nature. Transforming non-biodegradable HDPE waste into a valuable resource presents a formidable ecological challenge. This research aims to study CO2 and H2 gases toward HDPE-based membranes through the adsorption process with pressure and temperature variation. The highest CO2 and H2 adsorption capacities of 14.19 mmol.g − 1 (62.43 %wt) and 18.04 mmol.g−1 (3.61 %wt) were obtained by pressure feeding 3 bar at 30°C. The adsorption capacity decrease as the temperature increase. At an adsorption temperature of 50°C, the adsorption capacity of CO2 and H2 decrease, respectively by 75.86 % and 69.81 %. The adsorption kinetics were evaluated using pseudo-first order, pseudo-second order, and intraparticle diffusion models. The kinetic study shows that adsorption at 30°C follows the pseudo-second order. The adsorption at elevated temperatures reveals the intraparticle diffusion mechanism, indicating that the gas is adsorbed directly into the polymer matrix. Thermodynamic results include enthalpy of adsorption (ΔH), standard entropy of adsorption (ΔS), energy Gibbs (ΔG), and energy activation (Ea). ΔH CO2 and H2 are -22.339 and -23.654 kJ mol−1, respectively, which indicates that the process is exothermic and physisorption. The ΔS value shows that the irregularity and randomness of gas movement during the adsorption process, with the respective values for CO2 and H2 are -0.069 and -0.072 kJ mol−1 K−1, respectively. ΔG for adsorption of CO2 and H2 with increasing temperature becomes less spontaneous, which results in decreased adsorption capacity. Ea of CO2 is greater than H2, so the adsorption capacity of CO2 is smaller than H2. The thermodynamic study shows that the adsorption process is preferable at lower temperatures.

Dialysate fluid is a vital component in hemodialysis therapy. Processing and reusing spent dialysate in hemodialysis significantly reduces costs and produces environmentally friendly hemodialysis. In this research, mixed matrix membrane adsorbers (MMMAs), which have the potential to recycle spent dialysate, have been developed. MMMA is composed of cellulose acetate (CA)-based polymers synthesized from cellulose isolated from oil palm empty fruit bunches (OPEFB) and integrated with silica (Si) bio-adsorbent from rice husk ash waste. The membrane was cast using the phase inversion method to form MMMAs CA-Si. The MMMAs CA-Si has a porous structure with evenly distributed silica particles. The pristine CA membranes had swelling and porosity degrees of 38.89 % and 21.23 %, while the MMMAs CA-Si had swelling and porosity degrees of 41.43 % and 27.81 %, respectively. The pristine CA membrane had a clean water flux of 86.86 L/m2h, while the MMMAs CA-Si membrane had a 96.25 L/m2h clean water flux. The MMMAs CA-Si has a tensile strength of 15.89 (Kgf/mm2) and an elongation of 14.01 %. The pristine CA membrane had a creatinine adsorption capacity of 2.8 mg/g, while the CA-Si MMMAs membrane had a maximum adsorption capacity of 9.98 mg/g. The maximum adsorption capacity (qm) is 9.98 mg/g MMMAs, equivalent to 24.95 mg creatinine/g silica in MMMAs and the dissociation constant (Kd) value is 1.91 mg/L. Creatinine can be removed from the dialysate through a continuous flow dialysis process using MMMAs CA-Si with a total removal of 10.48 mg/g or above 66.45 %. Creatinine can also be filtered by cross-flow circulation, and the total creatinine removal is above 81.0 %. MMMAs CA-Si can be an alternative separation medium to remove creatinine in the dialysate.

The main challenge with membrane bioreactors is fouling, which leads to decreased flux performance and a shortened membrane lifespan. This study aims to provide a solution for the flux recovery and removal of irreversible fouling on Polyvinylidene Fluoride (PVDF) membranes without damaging their structure using sulfate radicals. Sulfate radicals are formed via peroxodisulfate precursors that are activated by Fe2+. The membrane flux recovery and irreversible fouling ratio were 88.45-99.04% and 11.60-0.96%, respectively, at operating temperatures of 298-308 K. The PVDF membrane has been tested for microfiltration and washed up to 6 times per cycle. The mechanical properties, XRD, SEM-EDX, and ATR-FTIR characterization of the PVDF membrane after washing with PDS/Fe2+ did not show a negative effect on the PVDF structure. Additionally, the results of the kinetic and thermodynamic studies showed that washing with PDS/Fe2+ inhibited the formation of fouling particles on the membrane surface. Based on this study, sulfate radical oxidants with PDS precursors activated by Fe2+ can be applied as cleaning chemicals for PVDF membranes without damaging their structures.

In response to global clean energy demands, this study develops mixed matrix membranes (MMMs) for gas separation in renewable energy applications. MMMs are produced through phase inversion by employing polysulfone and bimetallic-ZIF (Ni–Co-ZIF-67). Bimetallic-ZIF, formed in-situ by Co and Ni metals in water solvent with triethylamine, enhances gas selectivity. MMMs with 4 wt% bimetallic-ZIF, Co: Ni ratio of 9:1 (4Ni10Z67), exhibit remarkable selectivity: CO2/CH4 (21.19), H2/N2 (1.47), H2/CH4 (44.82), and N2/CH4 (30.40). Strong interactions between bimetallic-ZIF and CO2, facilitated by molecular sieving and Ni–Co sites, contribute to these results.

The development of transforming Belulang grass (Eleusine indica) fiber into high-value-added products has not been explored. Microcrystalline cellulose (MCC) is a promising natural material that has been widely used in several sectors. This study is focused on the MCC isolation from Belulang grass fibers using alkalization, bleaching, and acid hydrolysis. The effects of these treatments on the chemical composition, surface morphology, crystallinity, and thermal stability of the fibers were evaluated using various techniques. Fourier-transform infrared (FTIR) analysis confirmed the removal of lignin and hemicellulose content through treatments like alkalization and acid hydrolysis. Scanning electron microscopy (SEM) revealed a transformation in the fiber surface from a bundled structure to individual rods with average lengths of 15.64 μm after acid hydrolysis. Acid hydrolysis significantly increased the cellulose content by 119.2 %, while simultaneously reducing hemicellulose and lignin contents by 72.6 % and 84.1 %, respectively. X-ray diffraction (XRD) analysis demonstrated a remarkable increase in crystallinity index from 51.87 % to 75.76 % following hydrolysis. Moreover, thermogravimetric analysis (TGA) confirmed the enhanced thermal stability of MCC, with a decomposition temperature reaching up to 366.53 °C. These findings suggest that MCC derived from Belulang grass has the potential to be a sustainable alternative to synthetic materials for reinforcing biocomposites.

Nannochloropsis sp., which is abundant in the ocean and has a high carbohydrate content, has great potential if used as a raw material for bioethanol. However, the low concentration of microalgae in the culture medium (0.5-2 µg/L) and the small size of the microalgae Nannochloropsis sp. (2-8 µm) become problems in the harvesting process. This study aims to increase the concentration of Nannochloropsis sp. during the harvesting process using a LiCl-modified polyvinylidene fluoride (PVDF) membrane. In addition, a computational approach was used to select the best solvent for PVDF and explain the conformational changes of PVDF. The results showed that N-Methyl-2-pyrrolidone is the best solvent for PVDF polymer (the lowest solvation energy is -86.25 Kjmol−1, and the highest binding energy is 1.8 Kjmol−1). The membrane, with the addition of 2% LiCl, had the best performance, increased the microalgae concentration ten times (from 596.4 to 5098 ppm), flux (150 Lm−2h−1bar−1), and rejection (100%). Adding LiCl to the dope solution increased the water flux (from 516 to 614 Lm−2h−1bar−1), changed the PVDF conformation from alpha to beta, and decreased the hydrophobicity of the membrane (from 94.89 to 81.68 °). Layer pore fouling is the fouling that plays a role in reducing microalgae flux during microalgae filtration by Nannochloropsis sp. Meanwhile, the type of washing recommended to overcome layer pore fouling is rinsing by increasing the speed of the filtration flow and immersion in chemical compounds.

Functionalization of graphite by alkali activation and oxidation by chemical treatment has not been explored. The hydrophobic nature of carbon poses a particular challenge when used as an agent in water treatment applications in particular. Modification with hydrophilic groups on carbon makes carbon a promising material because of its good properties and used in various sectors. This study focused on the synthesis of hydrophilic activated carbon (HAC) from graphite by activation using sodium hydroxide (NaOH) and hydrophilization with ammonium persulfate (APS). The effects of functionalization on the surface chemical properties, wettability, and morphology were evaluated using various techniques. Fourier transform infrared (FTIR) analysis confirmed the functionalization results with the appearance of hydroxyl groups. X-ray photoelectron spectroscopy (XPS) analysis confirmed the carbon surface properties by total survey scan, showing the presence of N 1s and S 2p peaks on HAC. Contact angle values showed an increase in hydrophilicity from 88 ± 1.5° to 39 ± 1.0° for graphite and HAC, respectively. The absorption time also showed that HAC has active hydrophilic groups that can absorb water droplets in less than 0.60 s. The scanning electron microscopy (SEM) results also showed an increase in the number of pores on HAC. The methylene blue (MB) adsorption study showed that HAC had an adsorption capacity of 49.399 mg/g with a removal percent of 98.798 % at optimum conditions with an initial MB concentration of 50 mg/L, contact time of 240 minutes, and adsorbent dose of 0.1 g/100 mL. The adsorption kinetics of MB, AC, and HAC fitted well with the pseudo-second-order model. The Langmuir model provided the best fit to the experimental data, indicating a homogeneous and monolayer adsorbent surface. Accordingly, the synthesized HAC can effectively and reliably remediate wastewater contamination with organic pollutant.

CO2 hydrogenation as sustainable route for generation of value-added carbon feedstock is identified as green pathway for mitigation of greenhouse gasses emission. CO2 methanation is one of the promising solutions, which only requires reactions at atmospheric pressure while utilizing metal catalysts to overcome kinetic limitations. Metal catalysts can be promoted to alter reducibities, CO2 adsorption capacities, and H2CO2 dissociation potential. The role of metal promoter such as rare earth elements (Ce, Mn, Co, and La) and alkali and alkali earth metal (Li, Na, Ca, and K) will be discussed within the scope of CO2 methanation. The aspect of catalysts modification towards hydrogen dissociation potential and surface oxygen vacancy will be emphasized to enhance selectivity for methane. Another pathway for CO2 hydrogenation is via further conversion into longer chain molecules such as olefin and ethanol. The benefit of metal promoter will be discussed in this review on the effect towards promoting CC coupling reaction for producing longer chain alcohol and light olefin. The strategies to develop active catalysts for the coupling reaction of CC will be emphasized with the promoter introduction. For the hydrogenation of CO2 to longer chain molecules, the main metal catalysts Ni, Pd, Rh, and Co, and their modification with promoter such as Ga, Cu, and alkali metal Na, K will be discussed. A critical analysis of the CO2 methanation mechanism and further CC reaction to longer chain molecules will be discussed, particularly the effect of metal promoters to stabilize the intermediate and maneuver the catalytic reaction pathway into the desired products.

In an effort to further improvement of LSCF hollow fiber membrane properties in oxygen purification applications, this work studied the use of polyethylene glycol (PEG) with a different molecular weights of 2000, 3400 and 6000 Da as a pore former. A well-prepared hollow fiber membrane was successfully fabricated via extrusion followed by a sintering method. The results showed that the addition of PEG increased the viscosity of the dope suspension and formed a constant asymmetric pore configuration of the membrane after sintering at 1250 °C. The increasing molecular weight of PEG also leads to a decrease in the mechanical strength of the membranes, indicating that finger-like pores were sacrificed by forming irregular pores. The gas tightness was also examined under room temperature which showed that membrane with PEG 3400 achieved the best tightness with the nitrogen permeability of 3.55 × 10−5 mol·m−2·s−1·Pa−1. The oxygen permeation of the membranes was also influenced by the addition of PEG, where the highest oxygen permeation flux of 6.07 × 10−8 mol·cm−2·s−1 was obtained using a hollow fiber membrane with PEG 3400 due to the existence of the lowest dense layer thickness.

Membrane bioreactor (MBR) deteriorates due to fouling on the membrane pores, which can reduce the membrane performance. To reduce membrane fouling, the addition of inorganic filler can enhance the antifouling properties. This study investigates two different membrane preparation by thermally induced phase separation (TIPS) and dip coating methods to modify hollow fiber membrane with Silver Nanoparticles (AgNPs)-Zeolites used in MBR for industrial wastewater treatment. Performance was evaluated by analyzing the flux of water and wastewater, rejection, water content, and antifouling properties. Characterization result represented the synthesized silver nanoparticles had similar diffraction peak with commercial AgNPs, then the micrograph of AgNPs and zeolites addition membrane showed that the inorganic material had an octahedral shape representing zeolite crystal and irregular shape representing AgNPs. The addition of zeolites and AgNPs resulted in satisfying performance, increased flux, rejection, and antifouling properties.

This research aims to study the comprehensive identification of the synthesis, characterisation and performance tests of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and La0.7Sr0.3MnO3-δ (LSM) granule-form catalysts with a CeO₂ and NiO addition for the POM reaction. The LSCF and LSM powder were firstly prepared using the solid-state reaction method. The granules were firstly prepared in a form of pellet, then crushed and sieved into a size of ± 1mm. The performance study begins with a pre-treated process, by flowing 5% O₂ gas (30 mL.min-1) in the fixed-bed reactor at 600 °C. The product was analysed using Agilent HP 6890 gas chromatography equipped with an Agilent HP 19095P-Q04 column and a FID detector. The results showed that the LSCF achieved 50.03% methane conversion which is lower than the LSM performance of 56.41%. The CeO₂ addition in both the LSCF and LSM revealed an increasing performance by increasing the reaction time. NiO addition resulted in a slower increase in the reaction time, which can be caused by the rate of carbon deposition formation. Based on the obtained results, the bifunctional catalyst has the potential to be developed into another module with a larger effective surface area, such as a multiple-thin layer membrane or hollow fibre membrane.

Recently, natural gas (mostly methane) is frequently used as fuel, while hydrogen is a promising renewable energy source. However, each gas produced contains impurity gases. As a result, membrane separation is required. The mixed matrix membrane (MMM) is a promising membrane. The huge surface area and well-defined pore structure of zeolite templated carbon (ZTC)-based MMM allow for effective separation. However, the interfacial vacuum in MMM is difficult to avoid, contributing to poor separation performance. This research tries to improve separation performance by altering membrane surfaces. MMM PSF/ZTC was modified by annealing at 120, 150, and 190°C; coating using 0.01, 0.03, and 0.05 mol tetramethyl orthosilicate (TMOS); and a combination of both, i.e. annealing at 190°C and coating using 0.03 mol TMOS. MMM PSF/ZTC successfully significantly improved CO2/CH4 selectivity by a combination of annealing at 190°C and coating 0.03 mol TMOS from 1.37 to 5.90 (331%), and H2/CH4 selectivity by coating with 0.03 mol TMOS from 4.58 to 65.76 (1378%). The enhancement of selectivity was due to structural changes to the membrane that became denser and smoother, which SEM and AFM observed. In this study, annealing and coating treatments are the methods investigated for improving the polymer matrix and filler particle adhesion.

One of the biggest challenges in implementing microalgae-based biofuels is the effective harvesting process. Filtration membrane has become one of the flexible methods in microalgae harvesting. This study investigated the harvesting of Nannochloropsis sp. using a modified PVDF membrane at various LiCl as an additive with N-methyl-2-pyrrolidone (NMP) solvent. Harvesting of Nannochloropsis sp. with PVDF membrane has never been reported before. The addition of LiCl can improve the performance of PVDF membrane due to LiCl has a great affinity for water, resulted in inducing the formation of the pore structure of membrane. The optimum membrane composition was determined at various LiCl additive from 1% to 3% (w/w). The hydrophilicity of the membrane increased as indicated by the increasing of water permeance, which were 516, 546, 660, and 614 l m ^−2 h ^−1 bar ^−1 for neat PVDF, PVDF/LiCl-1, PVDF/LiCl-2, and PVDF/LiCl-3 membrane, respectively. PVDF/LiCl-2 membrane showed the highest water permeance and the highest total average permeance (150 l m ^−2 h ^−1 bar ^−1 ) with 100% rejection of Nannochloropsis sp. harvesting. The membranes was cleaned using sodium hypochlorite, citric acid, and nitric acid. The SEM results showed that the membrane after cleaning appears the algae particles in the membrane pore. Furthermore, algae particles were almost not visible on cleaned membrane. The FTIR results showed an absorption at 3401 cm ^−1 , which was a characteristic of the hydrogen N–H bond, also including a typical amide uptake (C=O) at 1648 cm ^−1 indicating protein appearance. Moreover, the cleaned membrane did not appear any absorption that indicates the foulant.

The hydrogen adsorption, kinetic and thermodynamic of adsorption onto the zeolite templated carbon (ZTC) were examined at the temperature range of 30-50 °C and ambient pressure. The ZTC was prepared from zeolite-Y template and sucrose carbon precursor by impregnation method and showed its specific surface area of 932 m2/g as well as 0.97 cm3/g for total pore volume. Analysis of physical and chemical characteristics for materials were performed using XRD, SEM, TEM and N2 isotherm. The results indicated that the ZTC has some ordered network structure of carbon and also exhibits the formation of carbon layer outside the zeolite micropore. We observed the ZTC for hydrogen adsorption both gravimetric and volumetric method up to 1.72 and 1.16 wt.% at the lowest temperature, respectively. The kinetic process at all studied temperature was best approximated by pseudo second order kinetic model. The aspects of thermodynamic such as heat of adsorption and the entropy change were -14.41 kJ/mol and -40.93 J/K mol, respectively. Both values was negative, indicating an exothermic reaction and low disorder at the hydrogen and ZTC interface, when the adsorption process took place. While, the enthalpy change value exhibits characteristic of physical process. The Gibbs energy change calculated at 30, 40 and 50 °C were -1.99, -1.59 and -1.19 kJ/mol, respectively, indicating a spontaneous adsorption process.

Penelitian ini bertujuan untuk menentukan kapasitas adsorpsi metilen biru dan kongo merah pada zeolit-X yang disintesis dari abu dasar. Adsorben zeolite-X disintesis dari abu dasar dengan metode peleburan menggunakan NaOH pada suhu 750oC dalam atmosfer udara. Hasil karakterisasi zeolit-X dari abu dasar dibandingkan dengan zeolit-X yang disintesis dari bahan murni. Kristalinitas dan luas permukaan zeolit-X dari abu dasar masih lebih rendah dibandingkan zeolit-X yang disintesis dari bahan murni. Luas permukaan zeolit-X dari abu dasar adalah 250,850 m2/g, sedangkan zeolit-X dari bahan murni sebesar 472,471 m2/g. Hasil uji kapasitas adsorpsi zeolit-X dari abu dasar untuk metilen biru dan kongo merah adalah 131,6973 mg/g dan 38,12684 mg/g, berturut-turut. Proses adsorpsi mengikuti persamaan isothermal Langmuir dengan mengikuti model kinetika adsorpsi orde kedua semu. Studi termodinamika mengindikasikan bahwa proses adsorpsi terjadi secara eksoterm dan bersifat spontan pada masing-masing temperatur

A preliminary study of the effect of magnesium-doped into betanine-sensitized TiO2 thin layers has been carried out computationally and experimentally. The computational calculation was performed to observe the effect of magnesium on the interaction molecular of betanine onto TiO2 surface, using Ti12O28H8 model cluster. It was found out that the distance of the oxygen on the anchoring site betanine with the Ti in TiO2/Mg cluster is shortercompare to that one in TiO2 cluster. This result confirms the bond between betanine and TiO2 is stronger in the case of Mg2+ incorporation. The Natural Population Calculation also confirms that the electron transport from betanine to the TiO2 is more facilitated after Mg2+ incorporation. These results are also supported by the HOMO-LUMO profile of TiO2-betanine and TiO2/Mg. The XRD and SEM measurement confirm those are no effect on the TiO2 structure and morphology with the incorporation of Mg2+. The thin-film UV-Vis measurement confirms there is a bandgap sift after the incorporation of Mg.

Mixed Matrix Membranes (MMMs) which consist of 0.3 wt.% Zeolite-Carbon Composite (ZCC) dispersed in BTDA-TDI/MDI (P84 co-polyimide) have been prepared through phase inversion method by using N-methyl-2-pyrrolidone (NMP) as a solvent. Membranes were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared (FTIR). Membrane performance was measured by a single gas permeation of CO2 and CH4. The maximum permeability of CO2 and CH4, which up to 12.67 and 6.03 Barrer, respectively. P84/ZCC mixed matrix membrane also showed a great enhancement in ideal selectivity of CO2/CH4 2.10 compared to the pure P84 co-polyimide membrane.

Harvesting microalgae is an important process to be carried out in the production of biodiesel from microalgae. The method of harvesting by filtration technique provides many advantages over other methods. Polymer is a membrane material that is often used for harvesting microalgae. However, polymer membranes have limited hydrophobic properties, thus, modification was needed to improve the hydrophilic properties and performance of polymer membranes. The polyvylene fluoride (PVDF) flat-sheet membrane has advantages over other membrane materials which are rated with a flux rate of 67.3 L / m2h and a rejection value of 100%. Then, the development with hollow fiber modulation on the PVDF membrane was considered very suitable, which was reported to have succeeded in increasing the membrane flux in the harvest of Scenedemus Acuminatus reaching up to 5136 L / m2h. The addition of PVDF with the inorganic additive LiCl was successful in increasing its hydrophilicity as the water permeation size increased up to 542 L / m2h. In addition, the use of triethyl phosphate (TEP) as a solvent is more environmentally friendly and compatible with PVDF membranes. As a result, it can increase membrane porosity by up to 92.7%. Apart from improving the membrane material, this review also reports the design and economic analysis to produce an effective and efficient of polymeric membranes for microalgae harvesting.

This research involved carrying out a unique micro-mesoporous carbon particle incorporation into P84 co-polyimide membrane for improved gas separation performance. The carbon filler was prepared using a hard template method from zeolite and known as zeolite-templated carbon (ZTC). This research aims to study the loading amount of ZTC into P84 co-polyimide toward the gas separation performance. The ZTC was prepared using simple impregnation method of sucrose into hard template of zeolite Y. The SEM result showing a dispersed ZTC particle on the membrane surface and cross-section. The pore size distribution (PSD) of ZTC revealed that the particle consists of two characteristics of micro and mesoporous region. It was noted that with only 0.5 wt% of ZTC addition, the permeability was boosted up from 4.68 to 7.06 and from 8.95 to 13.15 barrer, for CO2 and H2 respectively when compared with the neat membrane. On the other hand, the optimum loading was at 1 wt%, where the membrane received thermal stability boost of 10% along with the 62.4 and 35% of selectivity boost of CO2/CH4 and H2/CH4, respectively. It was noted that the position of the filler on the membrane surface was significantly affecting the gas transport mechanism of the membrane. Overall, the results demonstrated that the addition of ZTC with proper filler position is a potential candidate to be applicable in the gas separation involving CO2 and H2.

Oilfield produced water (OPW) has become a primary environmental concern due to the high concentration of dissolved organic pollutants that lead to bioaccumulation with high toxicity, resistance to biodegradation, carcinogenicity, and the inhibition of reproduction, endocrine, and non-endocrine systems in aquatic biota. Photodegradation using photocatalysts has been considered as a promising technology to sustainably resolve OPW pollutants due to its benefits, including not requiring additional chemicals and producing a harmless compound as the result of pollutant photodegradation. Currently, titanium dioxide (TiO2) has gained great attention as a promising photocatalyst due to its beneficial properties among the other photocatalysts, such as excellent optical and electronic properties, high chemical stability, low cost, non-toxicity, and eco-friendliness. However, the photoactivity of TiO2 is still inhibited because it has a wide band gap and a low quantum field. Hence, the modification approaches for TiO2 can improve its properties in terms of the photocatalytic ability, which would likely boost the charge carrier transfer, prevent the recombination of electrons and holes, and enhance the visible light response. In this review, we provide an overview of several routes for modifying TiO2. The as-improved photocatalytic performance of the modified TiO2 with regard to OPW treatment is reviewed. The stability of modified TiO2 was also studied. The future perspective and challenges in developing the modification of TiO2-based photocatalysts are explained.

The selection of the solvent during the membrane preparation process significantly affects the characteristics of the resulting membrane. The large number of organic solvents available for dissolving polymers renders this experimental approach ineffective. A computational approach can select a solvent using the solvation energy value approach. In addition, no organic waste is generated from the computational approach, which is a distinct advantage. A computational approach using the DFT/B3LYP/def2-TZVP RIJCOSX method was used to optimize the structure of polyethylene terephthalate (PET). The PET for the experiment was obtained from the utilization of plastic bottle waste. In addition, a review of the thermodynamics, geometry, HOMO-LUMO orbitals, and vibrational frequencies was conducted to validate the PET molecule against the experimental results. A conductor-like polarizable continuum model was used to determine the best solvent for dissolving the PET plastic waste. The results demonstrated that the Fourier Transform Infra-Red and Fourier Transform Raman spectra obtained from computational calculations were not significantly different from the experimental results. Based on a thermodynamic approach, computationally the Gibbs free energy (−724.723), entropy (0.0428), and enthalpy (−724,723 Kjmol ^−1 ) values of the PET dimer molecule are not much different from the experimental values (−601, 0.042, and −488 Kjmol ^−1 ). The computational approach was successful in selecting solvents that can dissolve PET plastic bottle waste. Phenol solvent has the lowest solvation energy value (−101.879 Kjmol ^−1 ) and the highest binding energy (2.4 Kjmol ^−1 ) than other solvents. Computational and experimental results demonstrated that the phenol solvent was able to dissolve PET plastic bottle waste better than the other solvents.

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°) were enhanced. Prior to the modification, the contact angle of the PVDF membrane was 90.24°, which shows hydrophobic 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.

Hollow fiber membranes of polyvinylidene fluoride (PVDF) were prepared by incorporating varying concentrations of hydrophilic surface-modifying macromolecules (LSMM) and a constant amount of polyethylene glycol (PEG) additives. The membranes were fabricated by the dry-wet spinning technique. The prepared hollow fiber membranes were dip-coated by hydrophobic surface-modifying macromolecules (BSMM) as the final step fabrication. The additives combination is aimed to produce hollow fiber membranes with high flux permeation and high salt rejection in the matter of seawater desalination application. This study prepares hollow fiber membranes from the formulation of 18 wt. % of PVDF mixed with 5 wt. % of PEG and 3, 4, and 5 wt. % of LSMM. The membranes are then dip-coated with 1 wt. % of BSMM. The effect of LSMM loading on hydrophobicity, morphology, average pore size, surface porosity, and membrane performance is investigated. Coating modification on LSMM membranes showed an increase in contact angle up to 57% of pure, unmodified PVDF/PEG membranes, which made the fabricated membranes at least passable when hydrophobicity was considered as one main characteristic. Furthermore, The PVDF/PEG/4LSMM-BSMM membrane exhibits 161 °C of melting point as characterized by the DSC. This value indicates an improvement of thermal behavior shows so as the fabricated membranes are desirable for membrane distillation operation conditions range. Based on the results, it can be concluded that PVDF/PEG membranes with the use of LSMM and BSMM combination could enhance the permeate flux up to 81.32 kg·m−2·h−1 at the maximum, with stable salt rejection around 99.9%, and these are found to be potential for seawater desalination application.

Zeolite-X is a potential material for CO2 adsorption. To increase the performance of zeolite-X, kapok fiber was used as a support material. The growth of zeolite-X on the surface of kapok was affected by activation of the surface. This research aims to optimize the immersion time of kapok fiber using NaOH in order to achieve high crystallinity of the zeolite-X. The Zeolite-X supported on kapok fiber was synthesized by the simple hydrothermal method at immersion time variation of 12 to 36 h. XRD results show that zeolite-X on kapok surface has the highest crystallinity at immersion time of 24 h. The topography of kapok surface from AFM indicates that the surface was damaged due to peeling reaction of NaOH. SEM results show that zeolite-X has grown on the kapok surface in considerable amounts. From TGA analysis, it was shown that the thermal stability of zeolite-X supported on kapok surface was up to 300 °C. Adsorption of CO2 measured by gravimetric method shows that CO2 adsorption capacitywas up to 15.097 wt.% at room temperature.

A series of carbon with ZSM-5 mesoporous (ZMC) and Ni/ZMC ZSM-5 templates were synthesized and gravimetrically known its adsorption capacity to H2 gases. ZMC carbon was synthesized using a hard template method at a carbonation temperature of 900 oC with sucrose as a source of carbon. A mesoporous ZSM-5 template was synthesized by using a hydrothermal method at an aging and crystallization temperature of respectively 60oC and 150oC for as long as 24 hours. The characterized result of ZMC carbon using XRD powder has shown a diffracted pattern of amorphous carbon. Impregnating Ni with ZMC carbon each resulted in 5%, 15% and 25% of weight, which in turn also resulted in a diffractogram pattern of Ni/ZMC-5, Ni/ZMC-15, and Ni/ZMC-25, where each patterns were uniform and had no additional peaks. The results of SEM-EDAX showed that Ni had been successfully impregnated on the surface of ZMC carbon with a random morphology surface of ZMC carbon. The isothermal results of adsorption – desorption of N2 showed that the larger the Ni loading on the supporting ZMC carbon, the smaller the surface area of the ZMC specific carbon. The distribution of the pore size that was counted by using the BJH method, which was applied to all the samples, was as big as 3,8 nm. The adsorption capacity of H2 was measured by using the gravimetry method at ambient temperature for Ni/ZMC-5, Ni/ZMC-15, and Ni/ZMC-25, which each gave a weight percentage of 0,331%; 0,663% and 0,649% respectively, whilst the ZMC carbon has a weight of 2,18%.

Zeolite X supported on fiber material (glasswool) was successfully synthesized using a simple hydrothermal method. Variation of immersion time and NaOH concentration were used for glasswool activation. Activation process of glasswool has effects toward crystallinity and growth of zeolite X on glasswool surface. The results of characterization using XRD, SEM and AFM showed that zeolite X crystal grew on glasswool surface with high crystallinity using NaOH concentration 4M for 24 h. BET surface area and pore characteristics were analyzed by N2 isothermal adsorption. Carbon dioxide adsorption measurement using gravimetric method showed that zeolite X supported on glasswool has capability to capture carbon dioxide at room temperature up to 2.83 weight %.

This research introduces zeolite carbon composite (ZCC) as a new filler on polymeric membranes based on the BTDA-TDI/MDI (P84) co-polyimide for the air separation process. The separation performance was further improved by a polydimethylsiloxane (PDMS) coating to cover up the surface defect. The incorporation of 1 wt% ZCC into P84 co-polyimide matrix enhanced the O2 permeability from 7.12 to 18.90 Barrer (2.65 times) and the O2/N2 selectivity from 4.11 to 4.92 Barrer (19.71% improvement). The PDMS coating on the membrane further improved the O2/N2 selectivity by up to 60%. The results showed that the incorporation of ZCC and PDMS coating onto the P84 co-polyimide membrane was able to increase the overall air separation performance.

This research is aimed to reveal the kinetics of Cd2+ and Pb2+ leaching from fly ash geopolymer as a promising and sustainable method to solve the problems of heavy metals contamination. The geopolymer was made by using fly ash of PT. IMPOMI in East Java, Indonesia and the ratio of SiO2/Al2O3 = 6.5, Solid/Liquid (S/L) = 3.59 and Na2SiO3/NaOH = 2.5. A solution of Cd (NO3)2 or Pb(NO3)2 were added at 1,000, 4,000, 8,000 or 16,000 ppm relative to the weight of fly ash. Compressive strength test of geopolymers was carried out at the end of day 7 after curing the geopolymer mixture at room temperature. Leaching tests for the kinetics and mechanisms studies were carried using TCLP method by immersing the resulted geopolymers into 0.01 M acetic acid solution. The ratio of geopolymer mass to the volume of acetic acid solution was 1:25. ICP-OES was used to measure the leached Cd2+ and Pb2+ while SEM-EDS was used to study the morphology and heavy metal distribution on the polished geopolymer cross section. It was found that the compressive strength of Cd2+ geopolymer was slightly higher than those of Pb2+-geopolymer. The strength of geopolymer decreased at higher concentration of heavy metal cations. The maximum strength (24.4 MPa) was shown by 4,000 ppm Cd2+ geopolymer while SEM-EDX images showed that Cd2+ and Pb2+ were distributed uniformly from the surface to the core of geopolymers. The leaching test reveals that more than 99.5 % of Cd2+ and Pb2+ were retained by geopolymer while in depth kinetics investigation of both Cd2+ and Pb2+ leaching shows that the leaching rate follows the first order rate law with two step leaching processes. The first originates from cations at the surface followed by cations from the bulk of geopolymer.

The aim of this study is to improve the performance of zeolite-A as an adsorbent material using cellulose acetate (CA) addition as a support membrane, for Ni2+ ions adsorption. The membrane is called as Cellulose Acetate/Zeolite-A (CA/ZA) membrane, which was prepared by a phase inversion-immersion method. The CA/ZA membrane was prepared in 12.5 wt% CA at various ZA loading of 0, 1, 2, 3, 4 wt%. The CA membrane with 3 wt% zeolite-A addition has the best performance with flux of 366.9 L.m 2h 1 at 2 bar of pressure and has 73.46 % porosity. The best CA/ZA membrane was used for Ni2+ adsorption at various pH of metal ion solution. It was found that the optimum pH condition for Ni2+ adsorption was 10, which can adsorb Ni2+ ion up to 66.11% with an adsorption capacity of 0.26 mg.cm-2. SEM-EDX characterization showed that Ni2+ ion was distributed in the CA/ZA membrane. FTIR spectra showed no new peak on the used membrane for adsorption, indicating the physical adsorption between Ni2+ ion and the membrane.

Zeolite-Y templated carbon (ZTC) has been activated with K2CO3 and ZnCl2. This research aims to compare the characteristics of ZTC with K2CO3 and ZnCl2 activation. ZTC was synthesized via impregnation method followed by carbonization. In this research, activation process was conducted at variation of activator/carbon weight ratio of 1 and 1.50. The activation was carried out by heating up impregnated carbon at 800 °C for 1 h followed by washing to remove inorganic salt. XRD and SEM results indicate that the use of different activator produce ZTC with varied structure and morphology. Diffractogram results showed that the graphitic peak decreased due to K2CO3 activation, whereas graphitic peak increased owing to ZnCl2 activation. Decreasing the graphitic peak indicates that ZTCs have higher pore structure formation. In addition, surface formation of ZTC activated by K2CO3 was higher than by ZnCl2 activation. The higher pore structure formation means the amount of carbon deposited on external surface material was decreased.