Luffa Sponge Research Articles

β-carotene production from soap stock by loofa-immobilized Rhodotorula rubra in an airlift photobioreactor

Abstract In this study, the soap stock as a sole carbon source was used for growing a carotenoid producing yeast (Rhodotorula rubra). The application of soap stock resulted in increase of carotenoids yield up to 5.36 folds when compared with the grown cultures on glucose. On the best Monod equation fitted on the specific growth rate (μ) data, the maximum specific growth rate (μm) and half-saturation concentration (KS) were respectively determined at 0.064 h−1 and 3.26 g L−1 for total fatty acids presented in soap stock. Further tests on the carotenogenesis process were carried out in a cell-immobilized airlift photobioreactor where the natural loofa sponge was used for immobilization of the cells. The performance of the bioreactor was statistically studied by the response surface methodology (RSM) where aeration rate of 0.11 vvm and light irradiation intensity of 2517 Lx provided an optimum condition for producing β-carotene with a specific production rate of 22.65 mg gcell−1 day−1.

High-density natural luffa sponge as anaerobic microorganisms carrier for degrading 1,1,1-TCA in groundwater

Anaerobic microorganisms were applied to degrade organic contaminants in groundwater with permeable reactive barriers (PRBs). However, anaerobic microorganisms need to select optimal immobilizing material as carrier. The potential of high-density natural luffa sponge (HDLS) (a new variety of luffa) for the immobilization and protection of anaerobic microorganisms was investigated. The HDLS has a dense structure composed of a complicated interwoven fibrous network. Therefore, the abrasion rate of HDLS (0.0068gs-1) was the smallest among the four carriers [HDLS, ordinary natural luffa sponge (OLS), polyurethane sponge (PS), and gel carrier AQUAPOROUSGEL (APG)]. The results suggest that it also had the greatest water retention (10.26 H2O-gdry carrier-g-1) and SS retention (0.21gdry carrier-g-1). In comparison to well-established commercialized gel carrier APG, HDLS was of much better mechanical strength, hydrophilicity and stability. Microbial-immobilized HDLS also had the best performance for the remediation of 1,1,1-TCA simulated groundwater. Analysis of the clone libraries from microorganism-immobilized HDLS showed the HDLS could protect microorganisms from the toxicity of 1,1,1-TCA and maintain the stability of microbial community diversity. The mechanism of HDLS immobilizing and protecting microorganisms was proposed as follows. The HDLS had a micron-scale honeycomb structure (30-40μm) and an irregular ravine structure (4-20μm), which facilitate the immobilization of anaerobic microorganisms and protect the anaerobic microorganisms.

Combination of zero-valent iron and anaerobic microorganisms immobilized in luffa sponge for degrading 1,1,1-trichloroethane and the relevant microbial community analysis.

1,1,1-Trichloroethane (1,1,1-TCA), a dense non-aqueous phase liquid (DNAPL), is relatively slow to remediate naturally; combination of zero-valent iron and immobilized microorganism is a potential means to accelerate DNAPL biodegradation. We first adopted high density luffa sponge (HDLS) as immobilized microorganism carrier. The experimental results demonstrated that (1) the supernatant liquid microorganisms were the optimal immobilized microorganisms for HDLS and (2) the combination of zero-valent iron and immobilized microorganisms accelerated 1,1,1-TCA transformation. Furthermore, in the long-term remediation process, anaerobic microorganisms produced reductant H2S which was beneficial to zero-valent iron PRBs. Through further study of the microbial community, we found that majority of the sulfate-reducing bacteria (SRB) perfectly adapted to the process of 1,1,1-TCA co-metabolism dechlorination. Desulfobulbus and Desulfococcus potentially were the special SRB that contributed significantly to TCA co-metabolism. Additionally, 1,1,1-TCA induced the generation of new SRB and stimulated the growth of majority of dominating methanogens. The results indicated that they played a constructive role in accelerating the dechlorination of 1,1,1-TCA, reduction of sulfate, and improving the production of CH4. Consequently, combination of zero-valent iron and immobilized microorganisms for remediating groundwaterby contaminated 1,1,1-TCA is a sustainable and green remediation technology. Especially for groundwater of SO42- type contaminated by 1,1,1-TCA, in the long-term course of combination degradation, cyclic utilization of H2S to prolong the service life of zero-valent iron PRBs. H2 and CH4 generated to capture as potential energy resource. Based on this, a tentative reaction mechanism for Fe0 biodegradation of 1,1,1-TCA was proposed.

Luffa sponge offsets the negative effects of aeration on bacterial cellulose production.

To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9lmin-1 ). However, with 0·5% LSM-CM and an aeration rate of 3lmin-1 , a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24gl-1 ). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8±0·4 to 6·6±0·4gl-1 ) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration.

Thermal destruction of luffa sponge under air and nitrogen

Luffa sponge is an agricultural product with large global production. In this study, we studied the effect of ashing temperature and atmosphere on the physicochemical characteristics of luffa sponge. All of the ashed samples are amorphous materials with porous structures. The luffa sponge ashed in air (LSA) and luffa sponge ashed in nitrogen (LSN) show analogous elemental compositions. However, the oxygen in the air can promote the incineration and combustion of luffa sponge, while nitrogen atmosphere can hinder the decomposition of organic compounds due to carbonization. Their pore characteristics, therefore, vary with temperatures and atmospheres. The BET surface area, total pore volume, and mesopore volume generally increase with ashing temperature, due to the thermal destruction of organic matter in luffa sponge. LSA samples exhibit relatively higher surface area and total pore volume than LSN samples. Their mesopore volumes, however, are comparable, attributed to the preservation of original pores from enlargement under nitrogen atmosphere. With characteristics of low cost, low density, and comparable pore properties with traditional adsorbents, luffa sponge is a potential adsorbent for organic pollutants and a carrier for catalysts.

Removing Trypan blue dye using nano-Zn modified Luffa sponge

This study has presented specific features that are examined to remove the Trypan blue dye from the waste using Luffa sponge (LS) and modified Luffa sponge with zinc nanoparticles (ZnNPs). Peroxidase enzyme was obtained from Euphorbia amygdaloides plant and it was used with the green synthesis of Zn nanoparticles. Luffa sponge was used to be a support material for immobilized nanoparticles and it also used in remediation work. The obtained membrane forms, fibrous materials, (LS, ZnNPs-LS) were characterized with SEM and XRD.LS and ZnNPs-LS were employed as adsorbent to be used for the removal of Trypan blue dye from aqueous via batch studies. Measurements were made for the equilibrium, pH, temperature, concentration of dye with UV–visible spectrometer (590nm; for Trypan blue dye). The optimum removal of Trypan blue dye was found at pH7, the equilibrium was attained within 30min. The thermodynamic properties ΔG0, ΔH0, and ΔS0 showed that adsorption of Trypan blue dye onto LS and ZnNPs-LS were spontaneous and endothermic. The equilibrium isotherm data were analyzed using Langmuir and Freundlich models and the sorption process was described by the Langmuir isotherm with maximum monolayer adsorption capacity of 45.32 and 47.3mg/g for LS and LS-ZnNPs at 303±1°K, respectively.

MnO2 Nanosheets Grown on Internal Surface of Macroporous Carbon with Enhanced Electrochemical Performance for Supercapacitors

Supercapacitor performance is strongly dependent on the utilization rate of electrode materials. In this paper, MnO2 nanosheets (MONSs) have been grown on the inner surface of macroporous carbon (MPC) for increasing the utilization rate. The MPC is prepared from luffa sponge fibers. The MPC possesses closely arranged straight channels at the micrometer scale, which makes the MONSs be able to grow on the inner surface. Because of sufficient exposure toward electrolyte, the MONSs exhibit high mass specific capacitance at different loadings such as 1332 F/g (150 μg/cm2) and 354 F/g (5690 μg/cm2). Because of the presence of the large pores allowing the electrolyte solution to access easily, the active materials are capable of working at high loadings, obtaining areal specific capacitance as high as 2.9 F/cm2. The assembled supercapacitors show a high specific energy of 194 μWh/cm2 at the specific power of 4.5 mW/cm2. As the luffa sponge is abundant and pollution-free in production, the MONSs/MPC is of high pr...

Multifunctional Nitrogen-Doped Loofah Sponge Carbon Blocking Layer for High-Performance Rechargeable Lithium Batteries.

Low-cost, long-life, and high-performance lithium batteries not only provide an economically viable power source to electric vehicles and smart electricity grids but also address the issues of the energy shortage and environmental sustainability. Herein, low-cost, hierarchically porous, and nitrogen-doped loofah sponge carbon (N-LSC) derived from the loofah sponge has been synthesized via a simple calcining process and then applied as a multifunctional blocking layer for Li-S, Li-Se, and Li-I2 batteries. As a result of the ultrahigh specific area (2551.06 m(2) g(-1)), high porosity (1.75 cm(3) g(-1)), high conductivity (1170 S m(-1)), and heteroatoms doping of N-LSC, the resultant Li-S, Li-Se, and Li-I2 batteries with the N-LSC-900 membrane deliver outstanding electrochemical performance stability in all cases, i.e., high reversible capacities of 623.6 mA h g(-1) at 1675 mA g(-1) after 500 cycles, 350 mA h g(-1) at 1356 mA g(-1) after 1000 cycles, and 150 mA h g(-1) at 10550 mA g(-1) after 5000 cycles, respectively. The successful application to Li-S, Li-Se, and Li-I2 batteries suggests that loofa sponge carbon could play a vital role in modern rechargeable battery industries as a universal, cost-effective, environmentally friendly, and high-performance blocking layer.

Liquid hot water pretreatment of multi feedstocks and enzymatic hydrolysis of solids obtained thereof

Agricultural feedstocks (brewers’ spent grain – BSG, corncob – CC, corn husk – CH, wheat straw – WS and Luffa sponge – LS) were pretreated by liquid hot water (LHW) in order to increase cellulose recovery and enzymatic saccharification. LHW-pretreatment resulted in hemicellulose solubilization, and solids enriched in cellulose. Chemical analysis showed different susceptibilities of the feedstocks to LHW-pretreatment and enzymatic hydrolysis. Pretreated feedstocks presented higher crystallinity (determined through X-ray diffraction) and thermal stability (determined through thermogravimetric analysis) than untreated feedstocks. SEM images confirmed the effect of LHW-pretreatment on structural changes. Moreover, enzymatic hydrolysis and cellulose conversion to glucose (CCG) were improved for pretreated feedstocks, with exception of LS. CCG (in relation to glucose potential on solids) followed the order: BSG>CH>WS>CC>LS. LHW-pretreatment showed to be a good technology to pretreat multi feedstocks and for improving the enzymatic hydrolysis of recalcitrant agricultural feedstocks to sugars, which can be further converted to ethanol-fuel and other value-added chemicals.

Hybrid design and energy absorption of luffa-sponge-like hierarchical cellular structures

Luffa sponge has hierarchical cellular structure with macro-pores and micro-pores. Its strength is greatly enhanced by the stiff inner-surface layer around the macro-pores. This hierarchical bio-cellular structure was mimicked to construct a hierarchical aluminum foam cylinder reinforced by stiff thin-walled carbon fiber reinforced plastic (CFRP) tubes. Compression behaviors of the luffa-sponge-like hierarchical foam cylindrical structures were revealed and it is found that the specific energy absorption (SEA) of the hierarchical structure is greatly improved compared with the pure aluminum foam cylinder. Interaction between the CFRP tube and the aluminum foam lets the SEA of the hierarchical cylinder is greater than the linear summation of the SEA of each component in the hierarchical foam. Through hybrid and hierarchical design, an ultra-light composite cellular structure with excellent energy absorption was developed.

Removal of Cr(VI) from aqueous solution using Fe-modified activated carbon prepared from luffa sponge: kinetic, thermodynamic, and isotherm studies

In this study, the removal of Cr(VI) from aqueous solution using Fe-modified activated carbon (AC-Fe) was investigated. AC-Fe before and after Cr(VI) adsorption was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller surface area. The effects of various parameters were investigated by batch experiments, such as contact time, temperature, pH, adsorbent dose, and initial Cr(VI). The results showed that the modification method greatly improves the adsorption property. The surface area of the activated carbon was relatively high (834.006 m2), and the Fe-AC structure was found to be a well-developed array of microvoids and mesopores. FTIR revealed that the abundance of O–H, N–H, C–O, metal-oxygen, and metal-hydroxyl functional groups on the surface of the Fe-AC may play an important role for the adsorption of Cr(VI). The optimum pH was 1 with maximum removal efficiency of 98.71%. The batch equilibrium data fitted well to the Langmuir isotherm (R2 = 0.9960) at 308 K, which indicated monolayer adsorption. Kinetic data were best fitted with the pseudo-second-order kinetic model, which was considered as the rate-limiting factor. The negative ΔG values confirmed the spontaneity of the adsorption process. Positive ΔH and ΔS values indicated endothermic and irreversible adsorption.

Analysis of Metabolites and Carbon Balance in the Biofilteration of Cumene Using Loofa Sponge as Biofilter Media.

A laboratory-scale biofilter study was performed to treat cumene-inoculated mixed culture of bacterial community and loofa sponge (Luffa cylindrica) as support media for a period of 120days in five distinct phases. The removal efficiency was obtained in the range of 40-85% with maximum elimination capacity of 700gm(-3)h(-1) at the inlet load of 1167gm(-3)h(-1). The result demonstrated that loofa sponge is good support media for the removal of cumene at higher loading rates. Loofa sponge was characterized via chemical analysis and analytical techniques such as XRD; FTIR; XPS; and CHN, and the result obtained confirms its suitability as biofilter media. The SEM results of loofa with inoculum shows the formation of a biofilm layer on the surface of loofa. The GC-MS analysis of leachate confirms the presence of different organic compounds such as acetaldehyde and 4-hydroxy-2-oxopentanoic acids which are stable metabolites during cumene biodegradation. About 12.69% of carbon present in inlet cumene was converted to biomass.

Preparation of hydrophilic luffa sponges and their water absorption performance

Hydrophilic luffa sponges are prepared by grafting polymerization of acrylamide (AM) on luffa cylindrica and subsequent partial hydrolysis under alkaline conditions. Attenuated total reflection infrared spectroscopy is used to verify the composition of the grafted (luffa-g-PAM) and hydrolyzed (luffa-g-(PAM-co-PAANa)) samples. Alkalization conditions, including aqueous NaOH concentrations, alkalization temperature, and time, are studied extensively. Optimized conditions are then obtained. The grafting percentage (GP) of polyacrylamide increases with the feed ratios of [AM]/[OH] and [Ce]/[OH], reaction temperature, and time. Furthermore, the GP can reach up to 160%. Pristine, alkalized, grafted, and hydrolyzed luffa sponges show rapid absorption kinetics, and the pseudo second-order rate equation is applied to describe their kinetic procedure. Reaction conditions, such as [AM]/[OH], [Ce]/[OH], reaction temperature and time, influence the water absorption capacities of grafted and hydrolyzed samples. The hydrolyzed luffa sponges particularly exhibit high water absorption capacities of 75gg−1. The absorption mechanism is also discussed.

Transition metal doped MnO2 nanosheets grown on internal surface of macroporous carbon for supercapacitors and oxygen reduction reaction electrocatalysts

In this work, transition metal (Fe, Co, Ni, and V) ions-doped MnO2 nanosheets (MONSs) have been grown on the internal surface of macroporous carbon (MC) derived from luffa sponge fibers for supercapacitors and electrocatalysts for oxygen reduction reaction (ORR). The MONSs were prepared by redox reaction between the MC and KMnO4 in solution at room temperature. By introducing the corresponding salts into the reaction solutions the transition metal ions were in situ doped into the MONSs during the growth process. The electrochemical performance of the MONSs was considerably enhanced by doping with appropriate elements. The Ni-doped MONSs exhibit the best performance for supercapacitors with a high specific capacitance of 445Fg−1at 1Ag−1, high energy density of 50 Wh kg−1at 0.9kWkg−1, and high capacitance retention of 93% after 1000 cycles. The Co doped MONSs show the best ORR electrocatalytic perfromance with onset potential at 0.01V, high operation stability, and near four electron transfer per oxygen molecule during the ORR process. Besides doping with appropriate metal ions growth on the internal surface of the MC contributes greatly to the excellent electrochemical performance of the MONSs, which increases the utilization efficiency of the active materials due to full exposure towards the electrolytes. We demonstrated that appropriate doping plus growth on internal surface is a good strategy to prepare high performance active materials for electrochemical applications.

Three-dimensional microscopic deformation measurements on cellular solids

The increasing interest in small-scale problems demands novel experimental protocols providing dense sets of 3D deformation data of complex shaped microstructures. Obtaining such information is particularly significant for the study of natural and engineered cellular solids for which experimental data collected at macro scale and describing the global mechanical response provide only limited information on their function/structure relationship. Cellular solids, in fact, due their superior mechanical performances to a unique arrangement of the bulk material properties (i.e. anisotropy and heterogeneity) and cell structural features (i.e. pores shape, size and distribution) at the micro- and nano-scales.To address the need for full-field experimental data down to the cell level, this paper proposes a single-camera stereo-Digital Image Correlation (DIC) system that makes use of a wedge prism in series to a telecentric lens for performing surface shape and deformation measurements on microstructures in three dimensions. Although the system possesses a limited measurement volume (FOV~2.8×4.3mm2, error-free DOF ~1mm), large surface areas of cellular samples can be accurately covered by employing a sequential image capturing scheme followed by an optimization-based mosaicing procedure. The basic principles of the proposed method together with the results of the benchmarking of its metrological performances and error analysis are here reported and discussed in detail. Finally, the potential utility of this method is illustrated with micro-resolution three-dimensional measurements on a 3D printed honeycomb and on a block sample of a Luffa sponge under compression.

A free-standing sulfur-doped microporous carbon interlayer derived from luffa sponge for high performance lithium–sulfur batteries

A sulfur-doped microporous carbon interlayer derived from luffa sponge is successfully employed as the polysulfide diffusion inhibitor in Li–S batteries.

Functionalized porous carbon with appropriate pore size distribution and open hole texture prepared by H2O2 and EDTA-2Na treatment of loofa sponge and its excellent performance for supercapacitors

Functionalized porous carbon with an appropriate pore size distribution and open hole texture was prepared via the H2O2 and EDTA-2Na treatment of loofa sponge followed by carbonization and KOH-activation. The product was employed as a supercapacitor electrode.

Experimental Evaluation of Evaporative Cooler Using Agro Materials

The purpose of the study is to investigate the direct evaporate cooler in hot and humid regions with two different types of agro-based materials. In our experimental study, the locally available agro materials luffa (Sponge Gourd), zizanioides (Vetiver) were used with various thickness and the experimental results were compared with mathematical values. The operating parameters of pad thickness, air velocity, were changed and the performance of the cooler was analyzed. A test rig was designed and fabricated to collect experimental data. The performance of the evaporative cooler was evaluated based on the ambient condition. The analysis of the data indicated that cooling saturation efficiency improve with decrease of air velocity and higher pad thickness. It was shown that zizanioides-based pad with 160[Formula: see text]mm thickness has the higher performance (88%) at 4.5[Formula: see text]m/s air velocity in comparison with luffa pad materials. The experimental results of outlet air temperature and number of transfer units (NTU) were compared with mathematical model. The test results were within the limit of 15% and 10% to mathematical values.

Pretreating Luffa Sponge (Luffa cylindrica L.) with Concentrated Phosphoric Acid and Subsequent Enzymatic Saccharification

Luffa was evaluated as a potential energy crop. A considerable amount of luffa sponge biomass can be grown in a vertical direction with approximately 70% polysaccharide content and low lignin content. When concentrated H3PO4 was employed to pretreat luffa sponge, hemicelluloses were the most sensitive component, followed by cellulose and lignin. Hemicellulose solubilization and cellulose loss positively responded to the elevated temperature, time, H3PO4 concentration, and dosage for pretreatment. However, lignin solubilization was not affected greatly. Although the initial hydrolysis rate was accelerated by increasing pretreatment temperature, the final glucose conversion was reduced as temperature was raised higher than 50 °C. Prolonging pretreatment time was positively correlated to enzymatic digestibility. When H3PO4 concentration was lower than 80%, the final glucose conversion was increased with increasing H3PO4 concentration. Increasing H3PO4 concentration to 84% for pretreatment caused the final glucose conversion to decrease slightly, although the hydrolysis rate was initially accelerated. Additionally, an improvement of glucose conversion was obtained with increasing the substrate-to-phosphoric acid ratio. However, the improvement was not cost-effective, as the ratio was lower than 1-to-8.

Compression Responses of Bio-Cellular Luffa Sponges

Crushing behaviors of luffa sponges were studied through mechanical experiments. Controlled by four-order hierarchical and anisotropic structures, luffa sponges exhibit anisotropic responses along axial, radial, and circumferential directions. The ultra-thin but stiff inner surface layer dominates the crushing behavior, endowing the axially compressed luffa cylinder with structural integrity, enhancing the elastic deformation and yielding strength. In radial, circumferential, and lateral compressions, after removing the inner surface layer, luffa sponges are compliant and have large quasi-linear deformation before densification, without a plateau characterized by yielding and deformation. Immersed into water, crushed luffa sponge cylinders recover their geometry completely. However, compression strength is only partially restored. Gradual damage of the inner surface layer in water immersing/drying cycles greatly weakens the compression strength. In the case of removal of the inner surface layer, crushed luffa sponge cylinders completely restore their quasi-linear deformation ability during the water immersing/drying cycles.