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Glycerol carbonate (GC) was synthesized by transesterification of glycerol with dimethyl carbonate (DMC) using calcium oxide (CaO) derived from eggshell as a catalyst. The best results of 96% glycerol conversion and 94% GC yield were achieved under the following reaction conditions: 0.08 mole ratio of CaO to glycerol, 1:2.5 mole ratio of glycerol to DMC, 60 degrees C reaction temperature, and 3 hours reaction time. As expected, CaO showed deteriorated catalytic performance when recycling as observed by a rapid decrease in GC yield. This research showed that the active CaO phase first was converted to calcium methoxide (Ca[OCH3](2)) and calcium diglyceroxide (Ca[C3H7O3](2)) and finally to carbonate phase (CaCO3) which can be confirmed by XRD patterns. According to the phase transformation, the basicity decreased from 0.482 mmol/g to 0.023 mmol/g, and basic strength altered from strong basic strength (15.0 < H_ < 18.4) to weak basic strength (7.2 < H_ < 9.8), resulting in the lower catalytic activity of the consecutive runs. Despite the fact that the GC selectivity was almost 100%, the reaction products (methanol and GC) were not obtained in their stoichiometric ratio and their extents corresponded with that of the catalyst phase transformation to CaCO3. The mechanism of CaO catalyzed transesterification based on the condensation reaction of glycerol and catalyst was proposed, and in situ formation of water-derivative species was hypothesized as a cause of CaO transformation. CaO could react with DMC and water, generating methanol and CaCO3. This enabled unconventional monitoring of catalyst deactivation by checking if the mole ratio of methanol to GC was higher than 2:1 of its reaction stoichiometric ratio. It was also demonstrated that calcination of post-run catalyst at 900 degrees C to CaO exhibited almost constant catalytic activity, and the mole ratio of methanol to GC was constant at its reaction stoichiometry (2:1) for at least 4 times use.

The purpose of this research was to learn the formation of biomedical scaffold material from gelatin by using titanate (Na

The process and energy intensifications for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate (DMC) using an eggshell-derived CaO heterogeneous catalyst were investigated. The transesterification reaction between glycerol and DMC was typically limited by mass transfer because of the immiscible nature of the reactants. By varying the stirring speed, it was observed that the mass transfer limitation could be neglected at 800 rpm. The presence of the CaO solid catalyst made the mass transport-limited reaction process more prominent. Mass transfer intensification using a simple kitchen countertop blender as an alternative to overcome the external mass transfer limitation of a typical magnetic stirrer was demonstrated. A lower amount of the catalyst and a shorter reaction time were required to achieve 93% glycerol conversion or 91% GC yield, and the turnover frequency (TOF) increased almost 5 times from 1.5 to 7.2 min−1 when using a conventional magnetic stirrer and countertop blender, respectively. In addition, using a simple kitchen countertop blender with 7200 rpm, the reaction temperature of 60 °C could be reached within approximately 3 min without the need of a heating unit. This was the result of the self-frictional heat generated by the high-shear blender. This was considered to be heat transfer intensification, as heat was generated locally (in situ), offering a higher homogeneity distribution. Meanwhile, the trend toward energy intensification was promising as the yield efficiency increased from 0.064 to 2.391 g/kJ. A comparison among other process intensification techniques, e.g., microwave reactor, ultrasonic reactor, and reactive distillation was also rationalized.

Biopharmaceuticals are commonly present in relatively low concentrations in aqueous solutions, making their detection and purification detrimental. In this work, we used novel aqueous biphasic systems based on glycerol formal (GF) to extract an important antibiotic - tetracycline. We report cloud points (solubility curve) and tie-lines for three ternary systems, containing GF, water, and inorganic salt (either K 3PO 4, K 2HPO 4, or K 2CO 3) at constant temperature of 298 K and at 0.1 MPa. The tie-line data of these ternary systems were correlated using the nonrandom two-liquid model, and binary interaction parameters of activity coefficients were estimated. The experimental and correlated tie-line data were compared in terms of average root-mean-square deviation and showed satisfactory agreements. The partition coefficients of tetracycline between two phases were measured, and corresponding extraction efficiencies were calculated. The maximum value of partition coefficient was 1551 for the system containing K 3PO 4, followed by values of 1145 and 927 for systems containing K 2CO 3 and K 2HPO 4, respectively. The calculated extraction efficiencies were very high - greater than 98.8%, demonstrating high potential for using aqueous biphasic systems based on GF for separation and purification processes.

The valorization of sewage sludge by black soldier fly larvae (BSFL) has gained attentions for sewage sludge management since the sludge can be reduced securely as well as larval biomass can be used for biorefineries application. Nevertheless, the BSFL growth was impeded while assimilating nutrition from sewage sludge due to the presence of extracellular polymeric substances (EPS) that had entrapped the essential nutrients inside. Accordingly, the pre-treatment of sewage sludge via anaerobic digestion at different pH was employed in this work to rupture the EPS structure and release more nutrients for larval growth. The results showed that larvae fed with raw sewage sludge had attained the lowest final larval weight (2.05 ± 0.38 mg/larva) as opposed to batches fed with pre-treated sewage sludges. This was because the soluble carbohydrate (more than 6.81 ± 1.31 mg of glucose/g sewage sludge) in EPS was released after anaerobic pre-treatment, facilitating larval assimilation for growth. Furthermore, it was observed that further increasing of pH for sewage sludge pre-treatment had led to lower final larval weight gained due to the inhibitory effect stemming from ammonia production at higher pH. The anaerobic pre-treatment of sewage sludge being executed at pH 3 for 8 days had achieved the highest final larval weight at 7.34 ± 0.97 mg/larva. The still low quality of sewage sludges after the pre-treatment also offered benefit, where high sewage sludge reduction and waste reduction index were recorded due to the necessity of BSFL to consume more sewage sludge in compensating the nutrients destitution in sludge. Lastly, the possibility of predicting final larval weight was successfully materialized via a statistical model derived from the multiple linear regression method. The derived model incorporated the interactive parameters of anaerobic pre-treated pH and durations at various combinations could predict the final larval weight.

Coconut endosperm waste (CEW) was treated by Rhizopus oligosporus via in situ and ex situ fermentations together with bioconversion into valuable black soldier fly larval biomass. The ex situ fermentation could overall enrich the nutritional compositions of CEW by hydrolyzing its complex organic polymers and exuding assimilable nutrients to enhance the black soldier fly larvae (BSFL) growth. Nevertheless, the larval gut bacteria were competing with Rhizopus oligosporus in in situ fermentation, derailing the hydrolysis processes and larval growth. Accordingly, the highest growth rates achieved were around 0.095 g/day, as opposed to only 0.065 g/day whilst using 0.5 wt% of Rhizopus oligosporus to perform ex situ and in situ fermentations, respectively. These were also underpinned by the greater amount of total CEW consumed when employing ex situ fermentation, with comparable metabolic costs to feeding on in situ-fermented CEW. The mature BSFL were subsequently harvested and the amounts of protein and lipid produced were assessed in terms of their feasibility for biodiesel production. While the statistical analyses showed that the larval protein yields derived from both fermentation modes were insignificant, the BSFL could attain higher lipid and protein productivities upon feeding with ex situ- rather than in situ-fermented CEW mediums. Better yet, the larval biodiesel quality measured in terms of the fatty acid methyl ester composition were not varied significantly by Rhizopus oligosporus through the fermentation process. Thereby, the presence of 1.0 wt% Rhizopus oligosporus was considered optimum to perform ex situ fermentation, giving rise to the acceptable growth of BSFL loaded with the highest lipid yield and productivity for producing biodiesel and protein simultaneously.

The potentiality of a microalgal-bacterial culture system was explored in bioremediating wastewater while generating biomass for biodiesel production. A pre-determined optimal activated sludge and microalgal ratio was adopted and cultivation performance was evaluated in both synthetic and municipal wastewater media for nitrogen removal along with biomass and lipid generation for biodiesel production. The microalgal-bacterial consortium grown in the municipal wastewater medium produced higher biomass and lipid yields than those in the synthetic wastewater medium. The presence of trace elements in the municipal wastewater medium, e.g., iron and copper, contributed to the upsurge of biomass, thereby leading to higher lipid productivity. Both the microbial cultures in the synthetic and municipal wastewater media demonstrated similar total nitrogen removal efficiencies above 97%. However, the nitrification and assimilation rates were relatively higher for the microbial culture in the municipal wastewater medium, corresponding to the higher microbial biomass growth. Accordingly, the feasibility of the microalgal-bacterial consortium for bioremediating real municipal wastewaters was attested in this study by virtue of higher biomass and lipid production. The assessment of fatty acid methyl esters (FAME) composition showed the mixed microbial biomasses comprised 80–93% C16 to C18 FAME species, signifying efficient fuel combustion properties for quality biodiesel requirements.

Carbon dioxide (CO2) has been anticipated as an ideal carbon building block for organic synthesis due to the noble properties of CO2, which are abundant renewable carbon feedstock, non-toxic nature, and contributing to a more sustainable use of resources. Several green and proficient routes have been established for chemical CO2 fixation. Among the prominent routes, this review epitomizes the reactions involving cycloaddition of epoxides with CO2 in producing cyclic carbonate. Cyclic carbonate has been widely used as a polar aprotic solvent, as an electrolyte in Li-ion batteries, and as precursors for various forms of chemical synthesis such as polycarbonates and polyurethanes. This review provides an overview in terms of the reaction mechanistic pathway and recent advances in the development of several classes of catalysts, including homogeneous organocatalysts (e.g., organic salt, ionic liquid, deep eutectic solvents), organometallic (e.g., mono-, bi-, and tri-metal salen complexes and non-salen complexes) and heterogeneous supported catalysts, and metal organic framework (MOF). Selection of effective catalysts for various epoxide substrates is very important in determining the cycloaddition operating condition. Under their catalytic systems, all classes of these catalysts, with regard to recent developments, can exhibit CO2 cycloaddition of terminal epoxide substrates at ambient temperatures and low CO2 pressure. Although highly desired conversion can be achieved for internal epoxide substrates, higher temperature and pressure are normally required. This includes fatty acid-derived terminal epoxides for oleochemical carbonate production. The production of fully renewable resources by employment of bio-based epoxy with biorefinery concept and potential enhancement of cycloaddition reactions are pointed out as well.

The purpose of this review is to reveal the lipid and protein contents in black soldier fly larvae (BSFL) for the sustainable production of protein and energy sources. It has been observed from studies in the literature that the larval lipid and protein contents vary with the rearing conditions as well as the downstream processing employed. The homogenous, heterogenous and microbial-treated substrates via fermentation are used to rear BSFL and are compared in this review for the simultaneous production of larval protein and biodiesel. Moreover, the best moisture content and the aeration rate of larval feeding substrates are also reported in this review to enhance the growth of BSFL. As the downstream process after harvesting starts with larval inactivation, various related methods have also been reviewed in relation to its impact on the quality/quantity of larval protein and lipids. Subsequently, the other downstream processes, namely, extraction and transesterification to biodiesel, are finally epitomized from the literature to provide a comprehensive review for the production of unconventional protein and lipid sources from BSFL feedstock. Incontrovertibly, the review accentuates the great potential use of BSFL biomass as a green source of protein and lipids for energy production in the form of biodiesel. The traditional protein and energy sources, preponderantly fishmeal, are unsustainable naturally, pressingly calling for immediate substitutions to cater for the rising demands. Accordingly, this review stresses the benefits of using BSFL biomass in detailing its production from upstream all the way to downstream processes which are green and economical at the same time.

This work aims to enhance the photocatalytic antibacterial performance of plastics according to the JIS Z 2801:2010 standard, and to determine their mechanical properties by studying: (i) the influence of calcination on titanium dioxide (TiO2), (ii) modification with different TiO2 concentrations, and, (iii) the effect of silane as a coupling agent. Acrylonitrile-butadiene-styrene plastics (ABS) and Escherichia coli (E. coli) were chosen as the model plastic and bacteria, respectively. The 500 &deg, C calcined TiO2 successfully provided the best photoantibacterial activity, with an approximately 62% decrease of E. coli colony counts following 30 min of exposure. Heat treatment improved the crystallinity of anatase TiO2, resulting in low electron-hole recombination, while effectively adsorbing reactants on the surface. ABS with 500 &deg, C-calcined TiO2 at the concentration of 1 wt % gave rise to the highest performance due to the improved distribution of TiO2. At this point, blending silane coupling agent could further improve the efficacy of photoantibacterial activity up to 75% due to greater interactions with the polymer matrix. Moreover, it could promote a 1.6-fold increase of yield strength via increased adherent bonding between TiO2 and the ABS matrix. Excellent photocatalytic and material stability can be achieved, with constant photocatalytic efficiency remaining for up to five reuse cycles without loss in the yield strength.

This work aims to enhance the photocatalytic antibacterial performance of plastics according to the JIS Z 2801:2010 standard, and to determine their mechanical properties by studying: (i) the influence of calcination on titanium dioxide (TiO2); (ii) modification with different TiO2 concentrations, and; (iii) the effect of silane as a coupling agent. Acrylonitrile-butadiene-styrene plastics (ABS) and Escherichia coli (E. coli) were chosen as the model plastic and bacteria, respectively. The 500 °C calcined TiO2 successfully provided the best photoantibacterial activity, with an approximately 62% decrease of E. coli colony counts following 30 min of exposure. Heat treatment improved the crystallinity of anatase TiO2, resulting in low electron-hole recombination, while effectively adsorbing reactants on the surface. ABS with 500 °C-calcined TiO2 at the concentration of 1 wt % gave rise to the highest performance due to the improved distribution of TiO2. At this point, blending silane coupling agent could further improve the efficacy of photoantibacterial activity up to 75% due to greater interactions with the polymer matrix. Moreover, it could promote a 1.6-fold increase of yield strength via increased adherent bonding between TiO2 and the ABS matrix. Excellent photocatalytic and material stability can be achieved, with constant photocatalytic efficiency remaining for up to five reuse cycles without loss in the yield strength.

Anaerobic co-digestion (ACD), where two or more substrates are digested simultaneously, is able to prevent the problems associated with mono-digestion. The aim of this study is to develop a simulation model of ACD of food waste (FW) with sewage sludge (SS) for biogas production coupled with pre-treatment, sludge handling and biogas upgrading using SuperPro Designer v9.0. The Design Expert v13 is employed to perform optimization and evaluate the effect of hydraulic retention time (HRT), sludge recycle ratio, water to feed ratio (kg/kg) and SS to FW ratio (kg/kg) on the methane flow, chemical oxygen demand (COD) and volatile solids (VS). The results show that the methane yield of 0.29 L CH4/g COD removed, COD removal efficiency of 81.5% and VS removal efficiency of 69.2% are obtained with a HRT of 38.8 days, water to feed ratio (kg/kg) of 0.048, sludge recycle ratio of 0.438 and SS to FW ratio (kg/kg) of 0.044. Economic analysis has shown this study is feasible with a payback time of 6.2 years, net present value (NPV) of $5,283,000 and internal return rate (IRR) of 10.2%. This indicates that the ACD of FW and SS is economically feasible in a larger scale.

The purpose of this research was to learn the formation of biomedical scaffold material from gelatin by using titanate (Na2Ti3O7), which is a newly synthesized derivative of titanium dioxide (TiO2) with gelatin. It was prepared by mixed several solutions and cross-linked molecules by heating and salt-leaching. The biomedical scaffold was formed, and its porosity depended on the size of the salt crystal. The mixture was designed by using a mixture design with three factors: gelatin, titanate, and deionized water to determine the optimal mixture for the tensile strength of the biomedical scaffold. The microstructure of the biomedical scaffold was studied using scanning electron microscopy (SEM). The findings revealed that Na2Ti3O7 thoroughly pen-extracted the biomedical scaffold, and the tensile strength of the gelatin/titanate scaffold was higher than the biomedical scaffold, which was formed using pure gelatin. By using the mixture design technique, the 14.73% gelatin, 0.2% Na2Ti3O7, and 85.07% DI water got the highest yield of tensile strength (1508.15 kP). This was an about 4.88% increase in the tensile strength property when compared with using TiO2.

The Office of the National Broadcasting and Telecommunications Commission has reported that, from 2014 to 2018, Thailand’s internet usage has grown six-fold to 3.3 million terabytes per annum. This market trend highlights one of the policies of Thailand 4.0, with the aim of making Thailand a hub for information transfer in ASEAN. As a result, there will be a massive demand growth for data storage facilities in the near future. Data centres are regarded as the brain and heart of the digital industry and are essential for facilitating businesses in organising, processing, storing and disseminating large amounts of data. As the energy demand for equipment cooling contributes to over 37% of the total energy consumption, the data centres of the world’s leading companies, such as Amazon, Google, Microsoft and Facebook, are generally located in cold climate zones, such as Iceland, in order to reduce operating costs for cooling. Due to this reason, the possibility of data centres in Thailand is limited. Beneficially, PTTLNG, as the first liquified natural gas (LNG) terminal in Thailand, has processed the import, receiving, storage and regasification of LNG. The high abundance of cold energy inherently presented in LNG is normally lost to the surroundings during regasification. Presently, PTTLNG’s LNG receiving terminal utilises a heat exchanger with propane as an intermediate fluid to transfer cold energy from LNG to water. This cold energy, in the form of cold water, is then used in several projects within the LNG receiving terminal: (1) production of electricity via an organic Rankine cycle capacity of 5 MWh, (2) cooling the air inlet of gas turbine generators to increase the generator efficiency, (3) replacing refrigerant heating, ventilation and air conditioning systems within buildings, (4) development of winter plantations with precision agriculture to replace imported products. Therefore, this study focuses on the potential and future use for LNG cold energy by performing a thermodynamic and economic analysis of the use of LNG cold energy as a source to produce cold water at 7 °C, with the total cold energy of 27.77 to 34.15 MW or 7934 t to 9757 t of refrigeration depending on the target pressure of the natural gas to replace the conventional cooling system of data centres. This research has the potential to reduce the cooling operation costs of data centres by more than USD 9.87 million per annum as well as CO2 emissions by 34,772 t per annum. In an economic study, this research could lead to a payback period of 7 years with IRR 13% for the LNG receiving terminal and a payback period of 2.21 years with IRR 45% for digital companies.

Direct use of syngas, a cheaper hydrogen-rich gas, instead of pure hydrogen, as a deoxygenating agent for biohydrogenated diesel (BHD) production is presented in this study. Low-cost palm fatty acid distillate (PFAD), an inedible byproduct from refining palm oil, is used as a feedstock in the presence of a Pd/C catalyst. The results indicate that syngas can be effectively used in BHD production, while the achieved BHD yield is slightly lower than that obtained from pure hydrogen. The liquid products contain mostly n-C15 and n-C17, which fall into a diesel range. Decarbonylation is a prominent pathway under both hydrogen and syngas atmospheres. It was found that CO in syngas can act as a reducing agent, which can remove an oxygen atom from fatty acid molecules to form alkenol that could be further reduced to alkene and then cyclized to cycloparaffins. After reactivation, the activity of the catalyst could be fully recovered for at least 4 reused cycles. Reaction pathways for the catalytic deoxygenation und...

A series of nickel catalysts i.e. nickel sulfide (NiS), nickel phosphide (NiP) and nickel carbide (NiC) was investigated for hydrotreating of spent coffee oil to produce bio-hydrotreated fuel (BHF). Catalytic tests were carried out at 375–425 °C and 20–40 bar of initial H 2 pressure (before heating) with reaction time of 0–3 h. The activity of the catalysts are in the order of NiC > NiP > NiS; however NiC tended to promote cracking reaction resulting in high gasoline and gaseous yields. On the other hand, although NiS gives the lowest oil conversion, it is favorable to diesel yield with lowest methanation and cracking activity. Compared with decarboxylation (DCO 2 ) and hydrodeoxygenation (HDO), decarbonylation (DCO) was the major route for deoxygenation of coffee oil for all the catalysts. The ratio of (DCO + DCO 2 ) to HDO (as represented by C n-1 /C n ) decreased in the order NiS > NiC > NiP. Ketones as intermediate products (ca. 3 wt%) were detected in case of NiP. They could be generated via rearrangement of alcohol and keto-enol tautomerism. Significant amount of aromatics (4 wt%) with some isomerization products (0.9 wt%) can also be observed in NiS catalyzed liquid products while trace amount of these compounds were detected for NiP and NiC catalysts. Physiochemical analysis of the diesel fraction exhibited satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL. Since main products are straight chain hydrocarbons, high cetane index (>110) could be achieved.

High-value chemicals can be converted from biomass and its derivatives by various methods. In this work, gluconic acid was obtained from photocatalytic conversion of glucose with synthesized TiO2. Moreover, another high-value chemical, xylitol, was firstly found from the photocatalysis in this work. Arabinose and formic acid are other co-products obtained from the reactions. Two surfactants, polyethylene glycol (PEG) and cetyltrimethylammonium bromide (CTAB), were used in conventional sol-gel (SG), ultrasonication sol-gel (US), and hydrothermal (HD) methods to fabricate TiO2 with different structural and textural properties. Appropriate surface area and phase composition of TiO2 for production of the highest yields of gluconic acid and xylitol were investigated. It was found that all surfactant-assisted fabrications increased surface area and anatase content of TiO2 photocatalysts, resulting in high glucose conversion and high yields of xylitol, arabinose and formic acid. The highest yield of xylitol (6.45%) was obtained from US/CTAB-TiO2. Unfortunately, the yield of gluconic acid did not increase by increasing time, because it was also decomposed during photocatalysis. The moderate photocatalysis was found from SG/PEG-TiO2 (100% anatase, surface area 5.93 m2/g) that provided the highest yield of gluconic acid (7.6%) in 120 min.

Titanate Ribbon (Na2Ti3O7) used in ABS plastic was synthesized to study the mechanical properties and to conduct test on the E-coli bacteria inhibition performance. The polymer blends of ABS/Na2Ti3O7 by Na2Ti3O7, was synthesized through alkaline hydrothermal reaction with 0.5 grams of titanium dioxide as a precursor with 20 ml. of sodium hydroxide (NaOH) at the concentration of 10 molar under the alkalinity at 200 ° c for 24 hours. The study on the microstructure by scanning electron microscope revealed that the Layered structure was shaped as a complete ribbon. The mechanical testing activities on the E-coli bacteria inhibition polymer mixed ABS/Na2Ti3O7; it was found that the mechanical properties for ABS/Na2Ti3O7, The results showed that tensile modulus and tensile strength of blending Na2Ti3O7 at 0.5 %wt was the highest. The result showed that E.coli could reduce up to 66.01%.

The aim of this present work is to enhance photoantibacterial performance on a surface of Acrylonitrile-Butadiene-Styrene (ABS) by mixing titanium dioxide (TiO2). The influences of different ratios for TiO2 under UV light irradiation were investigated according to JIS Z 2801: 2010 standard. 0.5%, 1% and 2% TiO2/ABS were formed by melting process with internal mixer and compression molding process. E.coli were chosen as a model of bacteria. The best photoantibacterial activity was provided by 0.5% TiO2/ABS. The result showed that E.coli could reduce up to 46.95%. However, a higher amount of TiO2 (i.e., 1% and 2% TiO2/ABS) obstructed the reaction, and E.coli was reduced to 42.6% and 36.08%, respectively. This was due to its aggregation observed from SEM image. For mechanical properties for TiO2/ABS, The results showed that tensile modulus and tensile strength of blending TiO2 at 0.5 %wt was the highest but the tensile was decreased when increasing TiO2 in polymer blended.

In the present work, a catalytic coated-wall microreactor was developed and tested for producing epoxidized methyl oleate in a solvent-free system. TiO 2 was coated inside the microcapillary reactor wall by a static method, while H 2 O 2 and ethylenediaminetetraacetic acid (EDTA) were used as oxidant and stabilizer, respectively. The weight percent of oxirane oxygen was determined according to ASTM D1652 and the reaction performance was evaluated as oxirane oxygen yield and selectivity. Without TiO 2 coated catalyst or formic acid, trace oxirane yield were obtained. Without EDTA as stabilizer, decomposition of H 2 O 2 occurred as bubbles formation causing system operation failure. The results indicated that TiO 2 coated catalyst as well as the presences of EDTA and formic acid were crucial for epoxidation reaction, and oxirane yield of 43.1% could be achieved at the optimal reaction temperature of 60 °C and residence time of 2.7 min. The results were compared with the data obtained from a batch reactor. Microcapillary reactor offers continuous operation with 23 times higher reaction rate of epoxide production than batch reactor. However, TiO 2 coated layer was partially peeled off over 3 h lead to decrease in epoxide yield.

The performances of sodium titanate nanotubes (Na-TT), hydrogen titanate nanotubes (H-TT), sodium titanate nanoribbons (Na-TR) and hydrogen titanate nanoribbons (H-TR) on adsorption, photodegradation of methylene blue (MB) and sedimentability were investigated. The intrinsic property of Na-TT with high hydroxyl groups (anionic) provided a strong electrostatic interaction between the MB (cationic) under dark condition. The equilibrium and kinetic adsorption were fitted with Langmuir isotherm models and the pseudo-second-order model, respectively. That is, Na-TT showed the best maximum adsorption capacity of 178.6 mg/g and adsorption kinetics of 0.119 g/mg·min. When the light is turned on, H-TT showed advance its photocatalytic reaction rate of 1.16 × 10 −2 min −1 compared with Na-TT (the reaction rate of 1.02 × 10 −2 min −1 ). This attributed the saturated MB adsorption on Na-TT obstructed capacity to absorb photons, and thus the reaction gradually occurred. For the separation of photocatalysts from the suspension by adding alum as coagulant, Na-TT afforded the best sedimentability of which remaining Na-TT in water was approximately 5%. This study demonstrates that adsorption, degradation and sedimentability were governed by the surface area and crystal structure, which revealed increasing the performance in the order TiO 2

The influence of TiO2 nanoparticles with different volume concentrations in water on heat transfer, friction and thermal performance is explored, and finite volume method is used to clarify the heat transfer in a tube inserted with twisted tape (TT). In the experiment, swirling tubes are generated by TT insert with the twisted ratio (y/w) of 3.0 in the range of Reynolds number between 5400 and 15,200. The mathematical modeling which involves the prediction of flow behaviors in a tube is also conducted. The concentration of nanofluid (ϕ) was varied from 0.07 % to 0.21 % by volume. The results revealed that TiO2 nanoparticles suspended in water enhanced thermal conductivity, and movement of TiO2 nanoparticles delivered energy exchange. Although an increase of TiO2 concentration led to an increase in friction due to small particles suspending in fluid, the heat transfer and thermal performance could enhance significantly. As compared to pure water, the presence of TT with TiO2 nanoparticles at ϕ = 0.07 %, ϕ = 0.14 % and ϕ = 0.21 % indicated a 0.7 %, 1.7 % and 3.1 % higher thermal performance, respectively. With a higher Reynolds number, the thermal performance would be less pronounced due to high flow friction. From the experimental results, the understanding in relation to the effects of TiO2 concentration and Reynolds number on Nusselt number (Nu), friction factor (f) and thermal performance factor (η) is presented for a wide range of thermophysics and heat transfer application.

Catalytic hydrotreating of algae bio-crude oil from hydrothermal liquefaction (HTL) of Nannochloropsis sp. was performed. Different Ni-based catalysts, including Ni/γ-Al2O3, Ni-Cu/γ-Al2O3, Ni-Re/γ-Al2O3, and Ni-Cu-Re/γ-Al2O3, (10%Ni, 5%Cu, 2.5%Re) were used in upgrading of the bio-crude oil. Most catalytic systems could effectively eliminate S and decrease the N and O contents, and enhance more than 20% improvement in the higher heating value (HHV) of the bio-oil (34 to 41–45 MJ/kg). Introducing only Cu could enhance the C O hydrogenation resulting in higher aromatic and alcohol compounds. While the addition of Re is effective for hydrodeoxygenation, it lowers denitrogenation due to amination reaction. Ni-Cu-Re/γ-Al2O3 ternary alloy offered the best results on the overall performance, achieving the highest upgraded bio-oil yield of 58 wt% and the highest energy recovery in the upgrading process (ERupgrade) of 64.6%. As ER in HTL process (ERHTL) was ca. 71.8%, the overall ER (ERoverall) from algae biomass to upgraded bio-oil of 46.4% can be achieved for Ni-Cu-Re/γ-Al2O3 catalyst. Carbon efficiency approx. 47.7% can be attained as the carbon in the algae biomass feedstock was retained in the upgraded bio-oil. In addition, reaction pathways for the formation of different hydrotreated products catalyzed by mono-, bi-, and tri- metallic Ni-Cu-Re have been proposed.

Oftentimes, the employment of entomoremediation to reduce organic wastes encounters ubiquitous shortcomings, i.e., ineffectiveness to valorize recalcitrant organics in wastes. Considering the cost-favorability, a fermentation process can be employed to facilitate the degradation of biopolymers into smaller organics, easing the subsequent entomoremediation process. However, the efficacy of in situ fermentation was found impeded by the black soldier fly larvae (BSFL) in the current study to reduce coconut endosperm waste (CEW). Indeed, by changing into ex situ fermentation, in which the fungal Rhizopus oligosporus was permitted to execute fermentation on CEW prior to the larval feeding, the reduction of CEW was significantly enhanced. In this regard, the waste reduction index of CEW by BSFL was almost doubled as opposed to in situ fermentation, even with the inoculation of merely 0.5 wt % of Rhizopus oligosporus. Moreover, with only 0.02 wt % of fungal inoculation size to execute the ex situ fermentation on CEW, it could spur BSFL growth by about 50%. Finally, from the statistical correlation study using principal component analysis, the presence of Rhizopus oligosporus in a range of 0.5–1.0 wt % was regarded as optimum to ferment CEW via ex situ mode, prior to the valorization by BSFL in reducing the CEW.

Oil extracted from spent coffee grounds is utilized as a renewable source for bio-hydrotreated fuel production. In the present work, oil yield up to 13% can be obtained by Soxhlet extraction with hexane as a solvent. As the extracted oil contained high content of free fatty acids (6.14%), therefore one step alkali-catalyzed for ester based biodiesel production is impractical. Hydrotreating of extracted oil was performed over two catalysts i.e. NiMo/γ-Al2O3 and Pd/C with different operating parameters i.e. reaction time, operating temperature, and H2/oil. It was found that the reaction time of 2 h and the reaction temperature of 400 °C are favorable operating conditions. The liquid products mostly consisted of n-pentadecane and n-heptadecane, which contain one carbon atom shorter than the corresponding fatty acid (Cn−1) i.e. palmitic and stearic acid, respectively. Unfavorable cracking of diesel product is pronounced at high temperature and prolonged reaction time. In addition, although increased H2/oil promoted overall reaction and hydrodeoxygenation activity (Cn−1/Cn decreased) for both catalysts, hydrocracking is enhanced over Pd/C, leading to significant increase in gasoline yield. Moreover, Pd/C gave higher olefin content in liquid product (22.3 wt%) than NiMo/γ-Al2O3 (4.8 wt%). However, NiMo/γ-Al2O3 shows higher isomerization activity. The amount of isoparaffins catalyzed by NiMo/γ-Al2O3 and Pd/C were 10.8 and 1.7 wt%, respectively. Physiochemical analysis of the diesel fraction exhibit satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL, while the cetane index was much higher than conventional diesel.

The increase of annual organic wastes generated worldwide has become a major problem for many countries since the mismanagement could bring about negative effects on the environment besides, being costly for an innocuous disposal. Recently, insect larvae have been investigated to valorize organic wastes. This entomoremediation approach is rising from the ability of the insect larvae to convert organic wastes into its biomass via assimilation process as catapulted by the natural demand to complete its lifecycle. Among the insect species, black soldier fly or Hermetia illucens is widely researched since the larvae can grow in various environments while being saprophagous in nature. Even though black soldier fly larvae (BSFL) can ingest various decay materials, some organic wastes such as sewage sludge or lignocellulosic wastes such as waste coconut endosperm are destitute of decent nutrients that could retard the BSFL growth. Hence, blending with nutrient-rich low-cost substrates such as palm kernel expeller, soybean curd residue, etc. is employed to fortify the nutritional contents of larval feeding substrates prior to administering to the BSFL. Alternatively, microbial fermentation can be adopted to breakdown the lignocellulosic wastes, exuding essential nutrients for growing BSFL. Upon reaching maturity, the BSFL can be harvested to serve as the protein and lipid feedstock. The larval protein can be made into insect meal for farmed animals, whilst the lipid source could be extracted and transesterified into larval biodiesel to cushion the global energy demands. Henceforth, this review presents the influence of various organic wastes introduced to feed BSFL, targeting to reduce wastes and producing biochemicals from mature larvae through entomoremediation. Modification of recalcitrant organic wastes via fermentation processes is also unveiled to ameliorate the BSFL growth. Lastly, the sustainable applications of harvested BSFL biomass are as well covered together with the immediate shortcomings that entail further researches.

The suspended microalgal cultivation systems targeting the production of lipid for biodiesel is still unable to meet the commercial and economic feasibility due to high energy and cost inputs during the harvesting process. Currently, the attached microalgal cultivation systems are known as an innovative technology to resolve the problematic aspects of suspended cultivation as the biomass can be easily separated from the culture medium with negligible energy input and no chemical need. Accordingly, this paper is focusing on reviewing various support materials utilized by researchers in growing the attached microalgal biomass in either fixed bed or fluidized bed bioreactor to ensure sustainable biomass production prior for biodiesel. An extensive review of the cultivation conditions impacting the growth of attached microalgal biomass is conducted in determining the optimized condition to enhance biomass productivity. The novelty of this paper is presented through in-depth analyses and discussions concerning the kinetic models and mechanisms study in selecting the suitable support materials for attached microalgal growth system. The incorporation of the cultivation condition parameter in predicting the growth of attached microalgae biomass via kinetic study is crucial in proffering new directions for technological developments and microalgal industry application. The ability of attached microalgal biomass in efficiently assimilate the nutrients available in the nutrient-rich wastewater for the microalgae growth is considered as an economical feasible approached. The suitable photobioreactor designs for growing the attached microalgal biomass are also discussed in detail in ensuring the sustainability of attached microalgal biomass production.

This review presents the extractions, characterisations, applications and economic analyses of natural coagulant in separating pollutants and microalgae from water medium, known as microalgae harvesting. The promising future of microalgae as a next-generation energy source is reviewed and the significant drawbacks of conventional microalgae harvesting using alum are evaluated. The performances of natural coagulant in microalgae harvesting are studied and proven to exceed the alum. In addition, the details of each processing stage in the extraction of natural coagulant (plant, microbial and animal) are comprehensively discussed with justifications. This information could contribute to future exploration of novel natural coagulants by providing description of optimised extraction steps for a number of natural coagulants. Besides, the characterisations of natural coagulants have garnered a great deal of attention, and the strategies to enhance the flocculating activity based on their characteristics are discussed. Several important characterisations have been tabulated in this review such as physical aspects, including surface morphology and surface charges; chemical aspects, including molecular weight, functional group and elemental properties; and thermal stability parameters including thermogravimetry analysis and differential scanning calorimetry. Furthermore, various applications of natural coagulant in the industries other than microalgae harvesting are revealed. The cost analysis of natural coagulant application in mass harvesting of microalgae is allowed to evaluate its feasibility towards commercialisation in the industrial. Last, the potentially new natural coagulants, which are yet to be exploited and applied, are listed as the additional information for future study.

Waste eggshell is proposed as a highly active catalyst for glycerol carbonate production from dimethyl carbonate (DMC) and glycerol. The effect of reaction temperature, reaction time and catalyst loading on the reaction performance were investigated in order to find a suitable operating condition. CaO derived from waste eggshell exhibits catalytic activity comparable to commercial CaO. By using CaO eggshell, glycerol conversion of 96% can be achieved within 90 min of reaction time under 2.5:1 feed molar ratio of DMC to glycerol, 0.08 mole ratio of CaO to glycerol and reaction temperature of 60°C. The catalyst was examined by XRD, TGA/DSC, SEM, N2 adsorption-desorption and Hammett indicators method. Utilization of eggshell as a catalyst for glycerol carbonate production not only provides a cost-effective and value-added of waste eggshell as a green catalyst, but also decrease amount of waste and its treatment cost which is ecologically friendly.

Titanium dioxide (TiO 2 ) in water as nanofluid was employed for heat transfer enhancement together with overlapped dual twisted tapes (O-DTs). The study encompassed Reynolds numbers from 5400 to 15,200, O-DTs with overlapped twist ratios ( y o / y ) of 1.5, 2.0 and 2.5 and nanofluids with TiO 2 volume concentrations ( ϕ ) of 0.07%, 0.14% and 0.21%. The experimental and numerical results indicated that O-DTs with smaller overlapped twisted ratio delivered a stronger swirl intensity and higher turbulent kinetic energy (TKE). The use of O-DTs at the smallest overlapped twist ratio of 1.5 enhanced heat transfer rates up to 89%, friction factor by 5.43 times and thermal performance up to 1.13 times as compared to those of plain tube. In addition, heat transfer increased as TiO 2 volume concentration of nanofluid increased, owing to the increases of contact surface and thermal conductivity. The simultaneous use of the O-DTs having twist ratios 1.5 with the nanofluid with TiO 2 volume concentration of 0.21% resulted in heat transfer enhancement around 9.9–11.2% and thermal performance improvement up to 4.5% as compared to the use of O-DTs alone. The empirical correlations of heat transfer rate ( Nu ), friction factor ( f ) and thermal performance ( η ) in a constant wall heat flux tube equipped O-DTs at different overlapped twist ratios ( y o / y ) and volume concentrations of TiO 2 nanoparticles ( ϕ ) are also reported for heat transfer applications.

The aim of this present work is to enhance thermal performance characteristics in a heat exchanger tube by studying: (i) multiple twisted tapes in different arrangements; (ii) TiO 2 nanoparticles with different concentrations as the working fluid. The tube inserted the multiple twisted tapes showed superior thermal performance factor when compared with plain tube or the tube inserted a single twisted tape, due to continuous multiple swirling flow and multi-longitudinal vortices flow along the test tube. The higher number of twisted tape inserts led to an enhancement of thermal performance that resulted from increasing contact surface area, residence time, swirl intensity and fluid mixing with multi-longitudinal vortices flow. Moreover, arrangement of twisted tapes in counter current was superior energy saving devices for the practical use, particularly at low Reynolds number. This was especially the case for quadruple counter tapes in the cross directions (CC-QTs) where heat transfer enhancement with relatively low friction loss penalty was deserved. The use of CC-QTs led to the highest thermal performance factor up to 1.45. Using water with TiO 2 nanoparticle as a working fluid yielded a higher thermal performance than using pure water. The tube inserted CC-QTs with TiO 2 /water nanofluid at concentration of 0.21% by volume provided the highest thermal performance factor 1.59, where heat transfer rate and friction factor increased to 3.52 times and 11.7 times of those in the plain tube with water as the working fluid.

The catalytic performance of nickel catalysts supported on La 2 O 3 , α -Al 2 O 3 , γ-Al 2 O 3 , ZrO 2 , and YSZ for supercritical water reforming of glycerol was investigated. Experiments were conducted in a tubular reactor made of Inconel-625 with the temperature range of 723–848 K under a pressure of 25 MPa. Carbon formation causing operation failure was observed for α -Al 2 O 3 , γ-Al 2 O 3 and ZrO 2 at temperatures higher than 748, 798 and 823 K, respectively. Ni/La 2 O 3 exhibited the highest H 2 yield where almost complete conversion was obtained at 798 K. Moderate space velocities ( WHSV = 6.45 h −1 ) and glycerol feed concentration (5wt.%) favor high hydrogen selectivity and yield. Methanation is favored at a low WHSV or high glycerol feed concentration, resulting in a lower H 2 yield. Increasing Ni loading on the Ni/La 2 O 3 catalyst strongly promoted the reforming, water–gas shift, and methanation reactions, which contributed significantly to the product species distribution.

This paper demonstrates the initiated use of relevant refining palm oil for bio-hydrogenated diesel production. The conversions of crude palm oil (CPO) and its physical refining including degummed palm oil (DPO) and palm fatty acid distillate (PFAD) to diesel fuel by hydroprocessing were studied. The effects of operating parameters (i.e. reaction time, operating temperature, and pressure) and catalyst (i.e. Pd/C and NiMo/γ-Al 2 O 3 ) were examined in order to determine suitable operating condition for each feedstock. It was found that the hydroprocessing of CPO with Pd/C catalyst at 400 °C, 40 bar, and reaction time of 3 h provides the highest diesel yield of 51%. When gum which contains phospholipid compounds is removed from CPO, namely DPO, the highest diesel yield of 70% can be obtained at a shorter reaction time (1 h). In the case of PFAD, which consists mainly of free fatty acids, a maximum diesel yield of 81% could be observed at milder conditions (375 °C with the reaction time of 0.5 h). The main liquid products are n -pentadecane and n -heptadecane, having one carbon atom shorter than the corresponding fatty acids according to decarboxylation/decarbonylation pathways. Pd/C catalyst shows good catalytic activity for fatty acid feedstocks but becomes less promising for triglyceride feedstocks when compared to NiMo/γ-Al 2 O 3 .

Glycerol reforming under catalytic supercritical water at temperatures in the range of 723–848 K using Co catalyst deposited on various supports including ZrO 2 , yttria-stabilized zirconia (YSZ), La 2 O 3 , γ-Al 2 O 3 , and α-Al 2 O 3 was investigated. An increase in operating temperature promoted the continued increase in glycerol conversion; however, carbon formation causing system operation failure was observed for γ-Al 2 O 3 and α -Al 2 O 3 at high operating temperatures (i.e. 748–798 K). Co supported on YSZ provided the most efficient performance for hydrogen production. 10 wt.% Co loading on YSZ support was an optimum amount to enhance the reaction. The increase in glycerol conversion and reduction of the amount of liquid products were observed for lower weight hourly space velocity (WHSV), higher operating temperature or higher cobalt loading. On Co/YSZ catalyst, glycerol conversion of 0.94 and hydrogen yield of 3.72 was obtained with WHSV of 6.45 h −1 at 773 K.

The photocatalytic activity of sodium titanate (Na 1.48 H 0.52 Ti 3 O 7 ), sodium hexatitanate (Na 2 Ti 6 O 13 ), and hydrogen titanate (H 2 Ti 3 O 7 ) nanoribbons and anatase TiO 2 nanorods were compared for water splitting, oxalic acid photodegradation and H 2 and O 2 generation using sacrificial agents. The intrinsic properties of the materials were found to affect their performance depending on the particular reaction system. The Na 2 Ti 6 O 13 nanoribbons, in the presence of RuO 2 co-catalyst, outperformed the anatase nanorods, for the water splitting reaction, generating over 10 times more H 2 /O 2 . This was thought to derive from their tunnel-like structure which provided better electron/hole separation when compared with TiO 2 . However, the efficient holes and electrons scavenging in the presence of sacrificial agents, methanol or AgNO 3 , to generate H 2 or O 2 , respectively, overwhelmed the tunnel-like structure effect. In this case photoactivity was governed by the crystal structure, with observed decreasing activity in the order TiO 2 >Na 2 Ti 6 O 13 >H 2 Ti 3 O 7 ∼Na 1.48 H 0.52 Ti 3 O 7 , and by the band gap of the semiconductor which determined its capacity to absorb photons in producing electron/hole pairs.

The role titanate particle structure plays in governing its characteristics upon calcining and their ensuing influence on photocatalytic performance was investigated. Titanate nanotubes and nanoribbons were prepared by hydrothermal treatment of Aeroxide P25 and then calcined at temperatures in the range 200 - 800 °C. Heat treatment directly transformed the nanotubes to anatase while nanoribbon transformation to anatase occurred via a TiO(2)(B) intermediate phase. The nanoribbon structure also provided an increased resistance to sintering, allowing for retention of the original {010} facet of the titanate nanosheets up to 800 °C. The changing material properties with calcining were found to influence the capacity of the particles to photodegrade oxalic acid and methanol. The nanotubes provided an optimum photoactivity following calcination at 500 °C with this point representing a transition between the relative dominance of crystal phase and surface area on performance. The comparatively smaller initial surface area of the nanoribbons consigned this characteristic to a secondary role in influencing photoactivity with the changes to crystal phase dominating the continually improving performance with calcination up to 800 °C. The structural stability imparted by the nanoribbon architecture during calcination, in particular its retention of the {010} facet at temperatures700 °C, advanced its photocatalytic performance compared with the nanotubes. This was especially the case for methanol photooxidation whose primary degradation mechanism relies on hydroxyl radical attack and was facilitated by the {010} facet. The effect was not as pronounced for oxalic acid due to its higher adsorption on TiO(2) and therefore greater susceptibility to oxidation by photogenerated holes. This study demonstrates that, apart from modulating sintering effects and changes to crystal phase, the titanate nanostructure influences particle crystallography which can be beneficial for photocatalytic performance.

Titanate nanoribbons were prepared by hydrothermal treatment of neat TiO2 P25 with 10 M NaOH at 200 °C. Hydrothermal aging times were varied to assist with understanding the transformation process while the impact of postsynthesis acid washing on nanoribbon formation kinetics was assessed. Nanoribbon evolution was observed to occur via the formation of intermediate amorphous titanate particles. The final nanoribbon product was found to comprise a layered titanate framework with sodium cations interspersed between the sheets. Acid washing served to exchange the Na+ with H+ to give H2Ti3O7. Moreover, acid washing accelerated nanoribbon formation, providing a well-defined (i.e., no amorphous particles) nanoribbon sample after 15 h compared to 40 h when acid washing was not used. The difference in formation rates was attributed to interlayer formation of the intermediates in the hydrogen bond array (i.e., Ti−O−H) during H2Ti3O7 being faster than intermediate formation in the sodium bond array (i.e., Ti−O−Na)....

The evolution of titanium oxide nanoribbons following different hydrothermal treatment times and acid washing was investigated. Titanium oxide nanoribbons could be obtained by hydrothermally treating TiO 2 with concentrated NaOH and with or without HCl post treatment. Without acid washing nanoribbon formation, without the co-existence of nanoparticles in the final sample, took 40 hrs. The hydrothermal treatment time required to form nanoribbons was halved when the sample was washed with HCl demonstrating acid washing accelerated nanoribbon formation. However, acid washing samples which were hydrothermally treated for 40 hrs was detrimental to the final nanoribbon structure. In this instance acid washing led to fragmentation of the nanoribbon morphology.