Membrane distillation (MD) is an advantageous separation process compared with pressure-driven technologies and was subsequently introduced to treat aquaculture wastewater. Harnessing a superhydrophobic membrane in an MD process is of extreme importance to prevent membrane wetting. In this work, the electrospun polypropylene (PP) membrane was surface modified by depositing an additional coating of PP via the solvent-exchange method, thereby improving the membrane's superhydrophobicity. Layer-by-layer deposition of PP caused the formation of uniform polymer spherulites on the membrane surface, which levelled up the membrane's surface roughness. A superhydrophobic surface was achieved by applying a single-layered PP coating, with static water contact angle of 152.2° and sliding angle of 12.5°. While all membranes achieved almost perfect salt rejection (up to 99.99%), the MD permeate flux improved by 30%, average of 13.0 kg/m2h, when the single-layered PP-coated membrane was used to treat the high salinity water in both 2 and 60 hr MD processes. Further layers of coating resulted in larger size of PP spherulites with higher sliding angle, followed by lowered flux in MD. The evenness of the surface coating and the size of the aggregate PP spherulites (nano-scaled) are two predominant factors contributing to the superhydrophobicity character of a membrane.
Surging growth of aquaculture industry has alarmed the public when the wastewater discharged had an adverse effect on the environment. This current study is a pioneer in the use of membrane distillation (MD) to treat real aquaculture wastewater. In addition to excellent hydrophobicity, the slippery surface of membrane used for MD is another key factor that enhances the performance of MD. The slippery surface of the membrane was tuned by layering high-viscosity and low-viscosity polypropylene (PP) polymers on the electrospun membrane by solvent-exchanged method. While the high-viscosity PP coating (PP/HV) rendered the membrane surface slippery, the low-viscosity PP coating (PP/LV) caused the fish farm wastewater to have stick-slip movement on the membrane surface. In the long-term 70-hour direct contact membrane distillation (DCMD) separation, PP/HV and PP/LV membranes can perfectly eliminate the undesirable components in the fish farm wastewater. The PP/HV membrane has registered a flux of 19.1 kg/m2·h, while the flux of PP/LV membrane was only 7.3 kg/m2·h. The PP/HV membrane also showed excellent anti-scaling properties in relative to the PP/LV membrane. This is because the PP/HV membrane promotes effortless gliding of the feed water along the surface of the membrane, while the surface of the PP/LV membrane has a static water boundary. Therefore, it can be concluded that the application of MD using the membrane coated with high-viscosity PP polymer is a feasible technology for the treatment of aquaculture wastewater.
Lemongrass leaves are often under-utilised and unexploited. In this study, lemongrass leaves were used to produce water soluble essential oil using a steam distillation system. Water steam was passed through the lemongrass leaves which were placed and supported on a grid above the water in a distiller. The steam distillation system was fabricated and optimised using Response Surface Methodology (RSM). The maximum oil yield with optimal relative citral content is obtained at 6.69 of plant-to-water ratio, 26.68 minutes of distillation time using air-dried lemongrass leaves left under the shade for two days. At the optimum conditions, the predicted oil yield was 0.6719% of lemongrass (C. citratus) oil which contains 71.79% of citral content.
Researchers in recent years have utilized a broad spectrum of treatment technologies in treating bakers' yeast production wastewater. This paper aims to review the treatment technologies for the wastewater, compare the process technologies, discuss recent innovations, and propose future perspectives in the research area. The review observed that nanofiltration was the most effective membrane process for the treatment of the effluent (at >95% pollutant rejection). Other separation processes like adsorption and distillation had technical challenges of desorption, a poor fit for high pollutant load and cost limitations. Chemical treatment processes have varying levels of success but they are expensive and produce toxic sludge. Sludge production would be a hurdle when product recovery and reuse are targeted. It is difficult to make an outright choice of the best process for treating the effluent because each has its merits and demerits and an appropriate choice can be made when all factors are duly considered. The process intensification of the industrial-scale production of the bakers' yeast process will be a very direct approach, where the process optimisation, zero effluent discharge, and enhanced recovery of value-added product from the waste streams are important approaches that need to be taken into account.
Rhodinol is a mixture of geraniol and citronellol. It is the second fraction in fractional distillation of commercially grown Cymbopogon nardus. The physical and chemical similarities of these two compounds made them inseparable. The individual use of each compound is of great importance. A selective oxidation (hydrogen peroxide activated by platinum black) of geraniol (in rhodinol) to geranial was done while remaining citronellol intact in order to separate the two compounds into different chemical functionality. A yield of 81% geranial achieved while minimizing citronellal formation from citronellol to 17%. Chemical separation using sodium hydrogen sulfite (NaHSO3) was done to separate the aldehydes from the unreacted citronellol. Purification using fractional distillation was done to obtain pure geraniol and remove minor fraction of citronellal.
Membrane distillation (MD) is a thermally driven technology applied in desalination and water reuse with utilisation of sustainable energy. However, algal organic matter (AOM) could foul membrane critically and plague MD's long-term operational stability. In this study, the soluble extracellular polymeric substance (sEPS) and intracellular organic matter with bound extracellular polymeric substance (IOM + bEPS) of two algal species (Amphora coffeaeformis and Navicula incerta) were exposed to 60 °C, 70 °C and 80 °C for 8 h with polypropylene hydrophobic membrane, simulating heated AOMs contacted with membrane inside MD unit, to study the temperature effect on membrane fouling. The dissolved carbohydrate and protein in the sEPS and IOM + bEPS samples generally increased after being heated. Heating caused cell lysis and the release and dissolution of carbohydrate and protein from sEPS, IOM and bEPS into water. As heating temperature increased, the carbohydrate release from the AOM usually increased. The contact angle of membrane contacted with sEPS and IOM + bEPS reduced significantly after heat treatment. The reduction in IOM + bEPS was larger than sEPS, in line with SEM analysis, indicating membrane surfaces and pores with IOM + bEPS fouled more severely than sEPS. It is due to higher hydrophobicity in IOM + bEPS causing adherence to membrane and presence of amphiphiles. High protein, lipid, and saturated fats proportions also cause severe fouling. SEM-EDX analysis indicated presence of O, Na, Cl and Mg elements, pointing to carbohydrate and lipids, and salt trapped in foulants. AOM heating and composition had direct effect to the membrane integrity, dictating severity of fouling in MD operations.
Membrane distillation (MD) frequently deals with membrane biofouling caused by deposition of algal organic matter (AOM) from algal blooms, hampering the treatment efficiency. In this study, AOMs, which are soluble extracellular polymeric substance (sEPS), bounded EPS (bEPS), and internal organic matter (IOM) from three benthic species (Amphora coffeaeformis, Cylindrotheca fusiformis, and Navicula incerta) were exposed to a temperature range to resemble the MD process. Results showed that EPS had higher polysaccharide fraction than protein with 85.71%, 68.26%, and 71.91% for A. coffeaeformis, N. incerta, and C. fusiformis, respectively. Both the EPS polysaccharide and protein concentration linearly increase with temperature, but the opposite was true for IOM and high-molecular-weight (HMW) polysaccharide. At 80°C, 5812.94 μg/g out of 6304.28 μg/g polysaccharide in A. coffeaeformis was of low molecular weight (LMW); hence, these findings suggested that they were the major foulants to clog the narrow pores within virgin hydrophobic membrane, forming a conditioning layer followed by deposition of HMW and hydrophilic polysaccharides onto the macropores to cause irreversible fouling. Cell lysis occurring at higher temperature increases the total protein content about 25% within the EPS matrix, inducing membrane plugging via hydrophobic-hydrophobic interactions. Overall, the AOM composition at different temperatures will likely dictate the fouling severity in MD. PRACTITIONER POINTS: EPS production of three benthic diatoms was the highest at 80°C. EPS from diatoms consists of at least 75.29% of polysaccharides. Small molecular weight carbohydrates (<12 kDa) were potential foulants. Proteins of internal organic matter (>56%) give irreversible attachment towards membranes. A. coffeaeformis was considered as the most fouling diatoms with highest EPS amount of 6304.28 μg/g.
Kaffir lime or “limau purut” (Citrus hystrix) is a popular traditional herbal plant with aromatic leaves. It produces fruits which are commonly used in Asian cuisines as a flavouring agent. Essential oil has been a popular and valuable product applicable in various industries, but its availability is scarce. Essential oil from the leaves of Citrus hystrix is a complex mixture of volatile and semi-volatile compounds. It is rich in bioactive molecules that act synergistically to improve the well-being of an individual. Essential oil is extracted from Citrus hystrix leaves using a few extraction methods; however, the most excellent extraction methods have yet to be ascertained. This review paper highlights several extraction methods that determined the final yield of Citrus hystrix leaves’ essential oil and the comparison of advantages and disadvantages between each method. Two types of methods are discussed, which are conventional and modern methods. Conventional methods include hydro-distillation, steam distillation, Soxhlet distillation and solvent extraction, while the modern method includes pressurized liquid extraction (PLE). In addition, pre- treatment processes are also included as they can significantly affect the performance of other important processes and production yield. This paper also found that the highest yield of 56.16% was obtained using PLE method. Essentially, each of the extraction and pre-treatment methods has its own pros and cons; hence choosing a suitable method depends heavily on the producer's demand and requirement.
Industrial heat pumps are heat-recovery systems that allow the temperature of waste-heat stream to be increased to a higher, more efficient temperature. Consequently, heat pumps can improve energy efficiency in industrial processes as well as energy savings when conventional passive-heat recovery is not possible. In this paper, possible ways of saving energy in the chemical industry are considered, the objective is to reduce the primary energy (such as coal) consumption of power plant. Particularly the thermodynamic analyses of integrating backpressure turbine of a power plant with distillation units have been considered. Some practical examples such as conventional distillation unit and heat pump are used as a means of reducing primary energy consumption with tangible indications of energy savings. The heat pump distillation is operated via electrical power from the power plant. The exergy efficiency of the primary fuel is calculated for different operating range of the heat pump distillation. This is then compared with a conventional distillation unit that depends on saturated steam from a power plant as the source of energy. The results obtained show that heat pump distillation is an economic way to save energy if the temperature difference between the overhead and the bottom is small. Based on the result, the energy saved by the application of a heat pump distillation is improved compared to conventional distillation unit.
The total mass attenuation coefficients (μ/ρ) of stainless steel (SS316L) and carbon steel (A516) that are widely used as petrochemical plant components, such as distillation column, heat exchanger, boiler and storage tank were measured at 662, 1073 and 1332 keV of photon energies. Measurements of radiation intensity for various thicknesses of steel were made by using transmission method. The γ-ray intensity were counted by using a Gamma spectrometer that contains a Hyper-pure Germanium (HPGe) detector connected with Multi Channel Analyzer (MCA). The effective numbers of atomic (Zeff) and electron (Neff) obtained experimentally were compared by those obtained through theoretical calculation. Both experimental and calculated values of Zeff and Neff were in good agreement.
In this study, simulation and optimisation of the purification of bioethanol from an azeotropic mixture was done using the Aspen HYSYS and the Response Surface Methodology (RSM), respectively, to achieve an acceptable bioethanol content with minimal energy use. The objective of this study is to develop the simulation process of bioethanol production from a fermentation effluent. Additionally, the effects of parameters such as solvent temperature, number of entrainer feed stage, mass flow rate and third components of the process for production of bioethanol were studied. As bioethanol is a product of biofuel production, the main challenge facing bioethanol production is the separation of high purity ethanol. However, the separation of ethanol and water can be achieved with the addition of a suitable solvent such as 1,3-butylene glycol (13C4Diol), mixture 13C4Diol and ethylene glycol (EGlycol) and mixture 13C4Diol and glycol ethyl ether (DEG) in the extractive distillation process. For the 13C4Diol mixture, the temperature of entrainer is 90oC with 1500 kg/hr of entrainer rate, while the number of entrainer feed stage is one. The optimum conditions for mixture 13C4Diol and EGlycol require a temperature of entrainer of 90.77oC with an entrainer rate of 1500 kg/hr, while the number of entrainer feed stage is one. Lastly, for optimum conditions for the mixture 13C4Diol and DEG, the temperature of entrainer should be 90oC with an entrainer rate of 1564.04 kg/hr, while the number of entrainer feed stage is one. This study shows that process simulation and optimisation can enhance the removal of water from an azeotropic mixture.
The fractions of fatty acid methyl esters (FAME) i.e. crude palm oil methyl esters (CPOME), RBD palm olein methyl esters (RBD Palm Olein ME) and used frying oil methyl esters (UFOME) rich in unsaturated fatty esters were used to prepare alkenyl succinic anhydrides (ASA). The fractions were obtained via fractional distillation that separated the unsaturated fatty esters from the saturated fatty esters. The fractions with the highest content of unsaturated fatty esters were reacted with maleic anhydride (MA) for 8 hours at 240oC with the MA/FAME ratio of 1.5. The reaction was conducted without catalyst and solvent. The crude alkenyl succinic anhydride (ASA) obtained was purified by column chromatography. The purified compound was characterised by FTIR.
In this work, poly(MBAAm-co-SBMA) zwitterionic polymer nanoparticles were synthesized in one-step via distillation-precipitation polymerization (DPP) and were characterized. [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) as monomer and N, N'-methylene bis(acrylamide) (MBAAm) as cross-linker are used for the synthesis of nanoparticles. As far as our knowledge, this is the first such report on the synthesis of poly(MBAAm-co-SBMA) nanoparticles via DPP. The newly synthesized nanoparticles were further employed for the surface modification of polysulfone (PSF) hollow fiber membranes for dye removal. The modified hollow fiber membrane exhibited the improved permeability (56 L/ m2 h bar) and dye removal (>98% of Reactive Black 5 and >80.7% of Reactive orange 16) with the high permeation of salts. Therefore, the as-prepared membrane can have potential application in textile and industrial wastewater treatment.
Functional surfaces and polymers with branched structures have a major impact on physicochemical properties and performance of membrane materials. With the aim of greener approach for enhancement of permeation, fouling resistance and detrimental heavy metal ion rejection capacity of polyetherimide membrane, novel grafting of poly (4-styrenesulfonate) brushes on low cost, natural bentonite was carried out via distillation-precipitation polymerisation method and employed as a performance modifier. It has been demonstrated that, modified bentonite clay exhibited significant improvement in the hydrophilicity, porosity, and water uptake capacity with 3 wt. % of additive dosage. SEM and AFM analysis showed the increase in macrovoides and surface roughness with increased additive concentration. Moreover, the inclusion of modified bentonite displayed an increase in permeation rate and high anti-irreversible fouling properties with reversible fouling ratio of 75.6%. The humic acid rejection study revealed that, PEM-3 membrane having rejection efficiency up to 87.6% and foulants can be easily removed by simple hydraulic cleaning. Further, nanocomposite membranes can be significantly employed for the removal of hazardous heavy metal ions with a rejection rate of 80% and its tentative mechanism was discussed. Conspicuously, bentonite clay-bearing poly (4-styrenesulfonate) brushes are having a synergistic effect on physicochemical properties of nanocomposite membrane to enhance the performance in real field applications.
A biosurfactant-producing and hydrocarbon-utilizing bacterium, Pseudomonas aeruginosa USM-AR2, was used to assist conventional distillation. Batch cultivation in a bioreactor gave a biomass of 9.4 g L(-1) and rhamnolipid concentration of 2.4 g L(-1) achieved after 72 h. Biosurfactant activity (rhamnolipid) was detected by the orcinol assay, emulsification index and drop collapse test. Pretreatment of crude oil TK-1 and AG-2 with a culture of P. aeruginosa USM-AR2 that contains rhamnolipid was proven to facilitate the distillation process by reducing the duration without reducing the quality of petroleum distillate. It showed a potential in reducing the duration of the distillation process, with at least 2- to 3-fold decreases in distillation time. This is supported by GC-MS analysis of the distillate where there was no difference between compounds detected in distillate obtained from treated or untreated crude oil. Calorimetric tests showed the calorie value of the distillate remained the same with or without treatment. These two factors confirmed that the quality of the distillate was not compromised and the incubation process by the microbial culture did not over-degrade the oil. The rhamnolipid produced by this culture was the main factor that enhanced the distillation performance, which is related to the emulsification of hydrocarbon chains in the crude oil. This biotreatment may play an important role to improve the existing conventional refinery and distillation process. Reducing the distillation times by pretreating the crude oil with a natural biosynthetic product translates to energy and cost savings in producing petroleum products.
Introduction: This is a proto-type product which is based on Frankincense essential oil and hydrosol. Methods: Three oleo gum resin species, namely; Boswellia carterii (BC), Boswellia frereana (BF), and Commiphora myrrha (CM) of Burceraceae family were extracted for their essential oil by hydro-distillation. They were screened for their poten-tial of anti-cariogenic activity by in-vitro experimental study of two main bacterial species (Streptococcus mutans and Lactobacillus spp), which are considered the main cause of dental and mouth diseases. Results: Methanol and acetone extracts of the three plants inhibited the growth of the bacteria. However, BF-methanol extract shows the greatest inhibition followed by BC and CM respectively. Hence, the obtained result encourages proceeding further thorough investigation to benefit the positive outcomes of these plant extracts in terms of introducing new potential antimicrobial formulations, such as mouth wash which can be used for mouth cleansing and protection from the diseases such as mouth ulcers, gingivitis, sinusitis, glandular fever and brucellosis as well as dental caries. This result can be converted to Boswellia Mouthwash Essential Oil (BosMEO) and Boswellia Mouthwash Hydrosol (BosMoHy) based products. This new plant extract product can be exploited for further research for its potential used as moth infection natural treatments such as mouth ulcers, gingivitis, sinusitis, glandular fever, brucellosis as well as respi-ratory problem. It is free of synthetic chemicals, organic, natural, plant based, and halal with no major health side effects. Conclusion: Plant-based product which is free from synthetic chemicals and with minimal side effects will satisfy its quality efficiency.
Membrane distillation (MD) is an attractive technology for the separation of highly saline water used with a polytetrafluoroethylene (PTFE) hollow fiber (HF) membrane. A hydrophobic coating of low-density polyethylene (LDPE) coats the outer surface of the PTFE membrane to resolve membrane wetting as well as increase membrane permeability flux and salt rejection, a critical problem regarding the MD process. LDPE concentrations in coating solution have been studied and optimized. Consequently, the LDPE layer altered membrane morphology by forming a fine nanostructure on the membrane surface that created a hydrophobic layer, a high roughness of membrane, and a uniform LDPE network. The membrane coated with different concentrations of LDPE exhibited high water contact angles of 135.14 ± 0.24 and 138.08 ± 0.01° for membranes M-3 and M-4, respectively, compared to the pristine membrane. In addition, the liquid entry pressure values of LDPE-incorporated PTFE HF membranes (M-1 to M-5) were higher than that of the uncoated membrane (M-0) with a small decrease in the percentage of porosity. The M-3 and M-4 membranes demonstrated higher flux values of 4.12 and 3.3 L m-2 h-1 at 70 °C, respectively. On the other hand, the water permeation flux of 1.95 L m-2 h-1 for M-5 further decreased when LDPE concentration is increased.
The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect.
Ethylene glycol is a super commodity chemical and it has vital roles in various applications. Its co-production with other chemicals, such as ethylene carbonate and glycerol carbonate, has promised cheaper production cost. Its quantification presents a challenge as its contaminants, such as ethylene carbonate, produce a signal-reducing effect in flame ionized detector. The aim of this study is to evaluate external standard to quantify the composition of glycol mixture. Measurement system analysis was employed on the external standard method. Reliability of the external standard is statistically significant with low p-values, excellent capability indices, and high F-values. The external standard is found to have remarkable precision and trueness as both capability indices are mirroring each other. Furthermore, the capability analysis has a strong correlation with quality measurement. Based on capability indices, the limit of detection is recommended at S/N = 25 and the limit of quantification is recommended at S/N = 100 for a reliable measurement. A high degree of reliability is achieved coherently as almost all uncertainties of coefficients of variations are less than 5%. The established method was validated and successfully applied to glycol mixture at azeotropic distillation pilot plant.
Two geometric shape turbulence promoters (circular and square of same areas) of different array patterns using three-dimensional (3D) printing technology were designed for direct contact membrane distillation (DCMD) modules in the present study. The DCMD device was performed at middle temperature operation (about 45 °C to 60 °C) of hot inlet saline water associated with a constant temperature of inlet cold stream. Attempts to reduce the disadvantageous temperature polarization effect were made inserting the 3D turbulence promoters to promote both the mass and heat transfer characteristics in improving pure water productivity. The additive manufacturing 3D turbulence promoters acting as eddy promoters could not only strengthen the membrane stability by preventing vibration but also enhance the permeate flux with lessening temperature polarization effect. Therefore, the 3D turbulence promoters were individually inserted into the flow channel of the DCMD device to create vortices in the flow stream and increase turbulent intensity. The modeling equations for predicting the permeate flux in DCMD modules by inserting the manufacturing 3D turbulence promoter were investigated theoretically and experimentally. The effects of the operating conditions under various geometric shapes and array patterns of turbulence promoters on the permeate flux with hot inlet saline temperatures and flow rates as parameters were studied. The distributions of the fluid velocities were examined using computational fluid dynamics (CFD). Experimental study has demonstrated a great potential to significantly accomplish permeate flux enhancement in such new design of the DCMD system. The permeate flux enhancement for the DCMD module by inserting 3D turbulence promoters in the flow channel could provide a maximum relative increment of up to 61.7% as compared to that in the empty channel device. The temperature polarization coefficient (τtemp) was found in this study for various geometric shapes and flow patterns. A larger τtemp value (the less thermal resistance) was achieved in the countercurrent-flow operation than that in the concurrent-flow operation. An optimal design of the module with inserting turbulence promoters was also delineated when considering both permeate flux enhancement and energy utilization effectiveness.