In this study, potassium oxide supported on dolomite adsorbent was used as an adsorbent for free fatty acids (FFAs) treatment in crude palm oil (CPO). The characteristics of the adsorbent were determined by TGA, XRD, SEM, BET and TPD-CO2. Taguchi method was utilized for experimental design and optimum condition determination. There were four parameters and three levels involved in this study: time (30, 60, 90 min), stirring rate (300, 500, 700 rpm), adsorbent dosage (1, 3, 5 wt%) and K2O concentration (5, 10, 15 wt%). The adsorbent had a larger pore size, higher basic strength, and more basic sites in greater efficiency (63%) in FFAs removal from CPO. The optimum conditions were at 30 min time, 700 rpm stirring rate, 5 wt% adsorbent dosage and 15 wt% K2O concentration. Taguchi method simplified determination of experimental parameters and minimized the operating costs.
This paper describes the synthesis of graphene-based activated carbon from carbonaceous rice straw fly ash in an electrical furnace and the subsequent potassium hydroxide extraction. The produced graphene has a proper morphological structure; flakes and a rough surface can be observed. The average size of the graphene was defined as up to 2000 nm and clarification was provided by high-resolution microscopes (FESEM and FETEM). Crystallinity was confirmed by surface area electron diffraction. The chemical bonding from the graphene was clearly observed, with -C=C- and O-H stretching at peaks of 1644 cm-1 and 3435 cm-1, respectively. Impurities in the graphene were found using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The measured size, according to zeta-potential analysis, was 8722.2 ± 25 nm, and the average polydispersity index was 0.576. The stability of the mass reduction was analyzed by a thermogravimetric at 100 °C, with a final reduction of ~ 11%.
Rice is an important staple crop produced and consumed worldwide. However, poor seed emergence is one of the main impediments to obtaining higher yield of rice especially in hot and dry ecosystems of the world that are ravaged by drought. Therefore, this study was carried out to evaluate the effects of potassium nitrate (KNO3), salicylic acid (SA) and silicon dioxide (SiO2) priming in improving emergence, seedling growth, biochemical attributes and antioxidant activities of FARO44 rice under drought conditions. Rice seedlings primed with 2.5% and 5% KNO3, 3% and 3.5% SiO2, and 1 mM and 2.5 mM SA were subjected to three drought levels of low, moderate and severe under the greenhouse. Seed emergence, seedling growth, biochemical attributes and antioxidant activities were thereafter evaluated. Seed priming experiments were laid in a completely randomized design with five replicates per treatment. The results found that rice seedlings responded differently to different priming treatments. However, all primed rice seedlings had significantly (P ≤ 0.05) improved emergence percentage (72-92%), seedling growth, seedling vigor, seedling fresh and dry biomass and shorter emergence time compared with controls. Likewise, total soluble protein content, activities of catalase, ascorbate peroxidase and superoxide dismutase, carbohydrate, soluble sugar and total chlorophyll contents of rice seedlings were increased by more than two-folds by seed priming compared with control. Salicylic acid showed less effect in increasing emergence, seedling growth, antioxidant activities and biochemical attributes of rice. Thus, this study established that seed priming with KNO3 (2.5% and 5%) and SiO2 (3% and 3.5%) were more effective in improving emergence, seedling growth, biochemical attributes and antioxidant activities of FARO44. Thus, priming of FARO44 rice with this chemical is recommended for fast emergence, seedling growth and drought resistance in dry ecosystems.
This study aimed at purification of phycocyanin (PC) from Phormidium tergestinum using an aqueous two-phase system (ATPS) comprised of polyethylene glycol (PEG) and salts. The partitioning efficiency of PC in ATPS and the effect of phase composition, pH, crude loading, and neutral salts on purification factor and yield were investigated. Results showed that PC was selectively partitioned toward bottom phase of the system containing potassium phosphate. Under optimum conditions of 20% (w/w) PEG 4000, 10% (w/w) potassium phosphate, 20% (v/v) crude load at pH 7, with addition of 0.5% (w/w) NaCl, PC from P. tergestinum was partially purified up to 5.34-fold with a yield of 87.8%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the molecular weight of PC was ∼19 kDa. Results from this study demonstrated ATPS could be used as a potential approach for the purification of PC from P. tergestinum.
Zinc-air batteries (ZABs) offer high specific energy and low-cost production. However, rechargeable ZABs suffer from a limited cycle life. This paper reports that potassium persulfate (KPS) additive in an alkaline electrolyte can effectively enhance the performance and electrochemical characteristics of rechargeable zinc-air flow batteries (ZAFBs). Introducing redox additives into electrolytes is an effective approach to promote battery performance. With the addition of 450 ppm KPS, remarkable improvement in anodic currents corresponding to zinc (Zn) dissolution and limited passivation of the Zn surface is observed, thus indicating its strong effect on the redox reaction of Zn. Besides, the addition of 450 ppm KPS reduces the corrosion rate of Zn, enhances surface reactions and decreases the solution resistance. However, excess KPS (900 and 1350 ppm) has a negative effect on rechargeable ZAFBs, which leads to a shorter cycle life and poor cyclability. The rechargeable ZAFB, using 450 ppm KPS, exhibits a highly stable charge/discharge voltage for 800 cycles. Overall, KPS demonstrates great promise for the enhancement of the charge/discharge performance of rechargeable ZABs.
The concern about our dependency on non-renewable resources and overwhelming environmental issues such as pollution caused by non-degradable packaging materials has prompted researchers to come up with alternatives to solve this problem. Thermoplastic polylactic acid (PLA) has been gaining interest due to its versatility and easy processability, thus this study was carried out to find out the properties of PLA reinforced with pineapple fibers. However, surface of the natural fibers need to be treated for better properties enhancement in the polymer matrices. Considering this, fibers were treated with 10% (w/v) concentration of potassium hydroxide (KOH) and then continued for mixing with PLA at a fixed ratio of plasticizer by using internal mixer, and then the composites were prepared into sheet via hot press. Characterization for the mechanical and morphological was conducted by using tensile testing and scanning electron microscopy, respectively. After the analysis, it is found that the surface treated pineapple fiber composite showed better elongation at break compared to untreated fiber composite. The enhance properties of PLA nanocomposites has potential to be used in various packaging materials.
Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.
Liquid biphasic flotation (LBF), an integrated process of liquid biphasic system (LBS) and adsorptive bubbles flotation, was used for the purification of C-phycocyanin from S. platensis microalgae. Various experimental parameters such as type of phase forming polymer and salt, concentration of phase forming components, system pH, volume ratio, air flotation time and crude extract concentration were evaluated to maximise the C-phycocyanin recovery yield and purity. The optimal conditions for the LBF system achieving C-phycocyanin purification fold of 3.49 compared to 2.43 from the initial LBF conditions was in polyethylene glycol (PEG) 4000 and potassium phosphate combination, with 250 g/L of polymer and salt concentration each, volume ratio of 1:0.85, system pH of 7.0, air flotation duration of 7 min and phycocyanin crude extract concentration of 0.625 %w/w. The LBF has effectively enhanced the purification of C-phycocyanin in a cost effective and simple processing.
Microalgae biorefinery is presently receiving a lot of attention as driven by its production of high value-added products. In this study, an oleaginous microalga Aurantiochytrium limacinum SR21 was cultured for docosahexaenoic acid (DHA) production using 20% (w/v) of K2HPO4-waste feedstock to replace 0.005% (w/v) of KH2PO4 in the flask culture. DHA is an essential nutrient for human's brain functionalities. Collectively, the K2HPO4-waste feedstock with working concentration of 0.005% (w/v) in the cultivation prompted a higher lipid content (8.29%) and DHA production (128.81 mg.L-1). Moreover, natural plant pigment products containing stabilised betacyanins were utilised as natural red colourants for hard candy production. This study develops microalgal cultivation using salt-rich waste feedstock for a higher lipid and DHA content as well as application of natural colouring agents in food products.
Adsorption technology has led to the development of promising techniques to purify biogas, i.e., biomethane or biohydrogen. Such techniques mainly depend on the adsorbent ability and operating parameters. This research focused on adsorption technology for upgrading biogas technique by developing a novel adsorbent. The commercial coconut shell activated carbon (CAC) and two types of gases (H2S/N2 and H2S/N2/CO2) were used. CAC was modified by copper sulfate (CuSO4), zinc acetate (ZnAc2), potassium hydroxide (KOH), potassium iodide (KI), and sodium carbonate (Na2CO3) on their surface to increase the selectivity of H2S removal. Commercial H2S adsorbents were soaked in 7 wt.% of impregnated solution for 30 min before drying at 120°C for 24 h. The synthesized adsorbent's physical and chemical properties, including surface morphology, porosity, and structures, were characterized by SEM-EDX, FTIR, XRD, TGA, and BET analyses. For real applications, the modified adsorbents were used in a real-time 0.85 L single-column adsorber unit. The operating parameters for the H2S adsorption in the adsorber unit varied in L/D ratio (0.5-2.5) and feed flow rate (1.5-5.5 L/min) where, also equivalent with a gas hourly space velocity, GHSV (212.4-780.0 hour-1) used. The performances of H2S adsorption were then compared with those of the best adsorbent that can be used for further investigation. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties (i.e., crystallinity and surface area). BET analysis further shows that the modified adsorbents surface area decreased by up to 96%. Hence, ZnAc2-CAC clarify as the best adsorption capacity ranging within 1.3-1.7 mg H2S/g, whereby the studied extended to adsorption-desorption cycle.
Banana peel (BP) is a major waste produced by fruit processing industries. Pre-treatment of BP at different temperatures led to 40% reduction in saponin at 100 °C (from 9.5 to 5.7 mg/g). Sequential mixed culture of Phanerochaete chrysosporium (P. chrysosporium) and Candida utilis (C. utilis) gave highest protein enrichment (88.93 mg/g). There is 26% increase in protein synthesis (from 88.93 to 111.78 mg/g) after media screening. Inclusion of KH2PO4, FeSO4·7H2O, wheat flour and sucrose in the media contributed positively to protein synthesis, while elevated concentration of urea, peptone, K2HPO4, KCl, NH4H2PO4, and MgSO4.7H2O are required to reach optimum protein synthesis. Total soluble sugar (TSS), total reducing sugar (TRS) and total carbohydrate (CHO) consumption varied with respect to protein synthesis in all experimental runs. Optimum protein synthesis required 6 days and inclusion of 5% sucrose, 0.6% NH4H2PO4, 0.4% KCl, and 0.5% MgSO4·7H2O as concentration media constituents to reach 140.95 mg/g protein synthesis equivalent to 300% increase over the raw banana peel protein content (35.0 mg/g).
Zinc-air flow batteries exhibit high energy density and offer several appealing advantages. However, their low efficiency of zinc utilization resulted from passivation and corrosion of the zinc anodes has limited their broad application. In this work, ethanol, which is considered as an environmentally friendly solvent, is examined as an electrolyte additive to potassium hydroxide (KOH) aqueous electrolyte to improve electrochemical performance of the batteries. Besides, the effects of adding different percentages of ethanol (0-50% v/v) to 8 M KOH aqueous electrolyte were investigated and discussed. Cyclic voltammograms revealed that the presence of 5-10% v/v ethanol is attributed to the enhancement of zinc dissolution and the hindrance of zinc anode passivation. Also, potentiodynamic polarization and electrochemical impedance spectroscopy confirmed that adding 5-10% v/v ethanol could effectively suppress the formation of passivating layers on the active surface of the zinc anodes. Though the addition of ethanol increased solution resistance and hence slightly decreased the discharge potential of the batteries, a significant enhancement of discharge capacity and energy density could be sought. Also, galvanostatic discharge results indicated that the battery using 10% v/v ethanol electrolyte exhibited the highest electrochemical performance with 30% increase in discharge capacity and 16% increase in specific energy over that of KOH electrolyte without ethanol.
An extractive bioconversion conducted on soluble starch with cyclodextrin glycosyltransferase (CGTase) enzyme in ethylene oxide-propylene oxide (EOPO)/potassium phosphates liquid biphasic system (LBS) to extract gamma-cyclodextrin (γ-CD) was examined. A range of EOPO (with potassium phosphates) molecular weights was screen to investigate the effect of the latter on the partioning efficency of CGTase and γ-CD. The results show that the optimal top phase γ-CD yield (74.4%) was reached in 35.0% (w/w) EOPO 970 and 10.0% (w/w) potassium phosphate with 2.0% (w/w) sodium chloride. A theoretical explanation for the effect of NaCl on γ-CD was also presented. After a 2 h bioconversion process, a total of 0.87 mg/mL concentration of γ-CD was produced in the EOPO/ phosphates LBS top phase. After the extraction of top phase from LBS, four continuous repetitive batches were successfully conducted with relative CGTase activity of 1.00, 0.86, 0.45, and 0.40 respectively.
Bioprotein is one of the useful products obtained from biotechnology invention. It is a promising replacement for the commercial fish feed supplement. In this study, the enrichment of the bioprotein content after solid state fermentation using palm kernel cake and seaweed by the white rot fungus: Phanerochaete chrysoporium and yeast: Candida utilis was carried out. The growth media components were selected from 11 types of media using Plackett-Burman design (hereinafter PBD) and were optimized by one-factor-at-a-time (OFAT) method with bioprotein concentration (mg/g) as the response. From the screening result using PBD, three media components, namely K2HPO4, CuSO4.5H2O and MnSO4.H2O were selected for further optimization using OFAT method because of their positive contributions to the response. The final results showed that 5.0 g/L K2HPO4, 3.0 g/L CuSO4.5H2O and 0.1 g/L MnSO4.H2O were there to be the optimum media constituents with 9.0 g/L, MgSO4.7H2O, 0.1 g/L, CaCl2.H2O, 3.0 g/L FeSO4.7H2O and 3.0 g/L peptone as fixed compositions. At this optimum concentration, the protein increment of 11% was observed as compared to the results determined in the screening using PBD. The study revealed the benefits of using mixed cultures in improving the protein concentrations which can be used as nutritious fish feed.
Mineral composition of rock has a very important influence on the physical and mechanical properties of tunnel surrounding rock. Take Dangjianshan tunnel in cold regions for example, the rock specimens in different parts of tunnel were taken to carry out the detection test of mineral composition. By the detail qualitative and quantitative analysis, the relationship between mineral composition and surrounding rock engineering properties was explored. First of all, the composition and content of minerals contained in in the rock specimens were detected by X ray fluorescence spectrometer and X ray powder diffraction. The detection results show that rock of tunnel contains high hardness minerals such as quartz and feldspar which were proven by initial engineering geological investigation report, in addition, it also contains several kinds of low hardness minerals including inclined chlorite and illite which may exhibit large deformation characteristic of soft rock after the tunnel excavation in case of meeting water and weathering conditions. The total content of inclined chlorite and illite accounted for a considerable component in main tunnel, inclined shaft and parallel pilot respectively and the influence on surrounding rock engineering properties cannot be ignored. Therefore, mineral composition detection must be paid attention to after tunnel excavation. Secondly, the effects of mineral composition on surrounding rock were analyzed in aspects of rock strength, weathering resistance, water softening property and excavation deformation through comparing the rock samples in different parts of tunnel. The comparative results showed that when the mineral contents is high with high hardness and poor hydrophilicity, tunnel surrounding rock plays a better performance of physical and mechanical properties, vice versa. Finally, according to the specific geological and construction parameters of the tunnel, the correlation analysis was studied about the vault settlement after tunnel excavation and the hydrophilicity mineral content in main cave. The logarithmic relationship between them was found and the correlation coefficient was 0.98. It can provide a useful reference for the settlement prediction of Dangjinshan tunnel construction.
The feasible use of aqueous two-phase systems (ATPSs) to establish a viable protocol for the recovery of laccase from processed Hericium erinaceus (Bull.:Fr.) Pers. fruiting bodies was evaluated. Cold-stored (4.00±1.00°C) H. erinaceus recorded the highest laccase activities of 2.02±0.04 U/mL among all the processed techniques. The evaluation was carried out in twenty-five ATPSs, which composed of polyethylene glycol (PEG) with various molecular weights and potassium phosphate salt solution to purify the protein from H. erinaceus. Optimum recovery condition was observed in the ATPS which contained 17% (w/w) PEG with a molecular weight of 8000 and 12.2% (w/w) potassium phosphate solution, at a volume ratio (VR) of 1.0. The use of ATPS resulted in one-single primary recovery stage process that produced an overall yield of 99% with a purification factor of 8.03±0.46. The molecular mass of laccases purified from the bottom phase was in the range of 55-66 kDa. The purity of the partitioned laccase was confirmed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
Lactobacillus kefiranofaciens is non-pathogenic gram positive bacteria isolated from kefir grains and able to produce extracellular exopolysaccharides named kefiran. This polysaccharide contains approximately equal amounts of glucose and galactose. Kefiran has wide applications in pharmaceutical industries. Therefore, an approach has been extensively studied to increase kefiran production for pharmaceutical application in industrial scale. The present work aims to maximize kefiran production through the optimization of medium composition and production in semi industrial scale bioreactor. The composition of the optimal medium for kefiran production contained sucrose, yeast extract and K2HPO4 at 20.0, 6.0, 0.25 g L(-1), respectively. The optimized medium significantly increased both cell growth and kefiran production by about 170.56% and 58.02%, respectively, in comparison with the unoptimized medium. Furthermore, the kinetics of cell growth and kefiran production in batch culture of L. kefiranofaciens was investigated under un-controlled pH conditions in 16-L scale bioreactor. The maximal cell mass in bioreactor culture reached 2.76 g L(-1) concomitant with kefiran production of 1.91 g L(-1).
Aqueous two-phase system (ATPS) extractive bioconversion provides a technique which integrates bioconversion and purification into a single step process. Extractive bioconversion of gamma-cyclodextrin (γ-CD) from soluble starch with cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) enzyme derived from Bacillus cereus was evaluated using polyethylene glycol (PEG)/potassium phosphate based on ATPS. The optimum condition was attained in the ATPS constituted of 30.0% (w/w) PEG 3000 g/mol and 7.0% (w/w) potassium phosphate. A γ-CD concentration of 1.60 mg/mL with a 19% concentration ratio was recovered after 1 h bioconversion process. The γ-CD was mainly partitioned to the top phase (YT=81.88%), with CGTase partitioning in the salt-rich bottom phase (KCGTase=0.51). Repetitive batch processes of extractive bioconversion were successfully recycled three times, indicating that this is an environmental friendly and a cost saving technique for γ-CD production and purification.
Purification of cyclodextrin glycosyl transferase (CGTase) from Bacillus cereus using polyethylene glycol (PEG)-potassium phosphates aqueous two-phase flotation (ATPF) system was studied in this paper. The effects of varying PEG molecular weight, tie-line length (TLL) value, volume ratio (VR), pH value, crude concentration and gas nitrogen flotation time were investigated. The optimal condition for purification of CGTase was attained at 18.0% (w/w) PEG 8000, 7.0% (w/w) potassium phosphates, VR of 3.0, 20% (w/w) crude load at pH 7, and 80 min nitrogen flotation time at a flow rate of 5 L/min. With this optimal condition, purification factor (PFT) of 21.8 and a yield (YT) of 97.1% were attained. CGTase was successfully purified in a single downstream processing step using the ATPF.
Steam explosion of oil palm frond has been carried out under different temperatures between 180 and 210°C for 4 min (severity of 2.96-3.84) after impregnation of the frond chips with water or KOH solution. The effects of impregnation and steam explosion conditions of oil palm fronds on the water soluble fraction and insoluble fraction were investigated. The maximum yield of hemicelluloses in water soluble fractions recovered was 23.49% and 25.33% for water and KOH impregnation, treated with steam explosion at temperature of 210°C (severity of 3.84) with a fractionation efficiency of 77.30% and 83.32%, respectively. Under this condition, the water insoluble fractions contained celluloses at 60.83% and 64.80% for water and KOH impregnation, respectively. The steam explosion temperature of 210°C for 4 min (logR(o) 3.84) was found to be the best condition in the extraction of hemicelluloses from OPF for both types of impregnation.