The use of agricultural wastes as raw materials to produce adsorbents for treating dye wastewater is a remarkable research topic. Given that maize (Zea mays L.) is one of the most productive crops, a ...large amount of discarded corn-cobs is not utilized every year. In this work, solid residues from corn-cobs hydrolyzed by oxalic acid were modified with polyethyleneimine (PEI) and catechol to form adsorbents. The adsorption performances for Congo red (CR) dye were measured, including the effects of initial solution concentration, temperature, and adsorption time. The maximum equilibrium adsorption capacity for CR was ∼650 mg/g at 30 °C, which exceeded that of many biomass-based adsorbents reported in recent literature and even reached the level of some carbon materials. The adsorption of CR molecules followed the pseudo-second-order kinetics. The thermodynamic interaction between CR molecules and the adsorbents was an endothermic process. The adsorption state of the CR molecules on the adsorbents was Langmuir monolayer adsorption, and the adsorption type was physical adsorption. The thermal stability of the adsorbents was similar to that of corn-cobs.
Display omitted
•Corn cobs is prepared as adsorbent through acid hydrolysis and PEI modification.•Experimental adsorption capacity for Congo red is 650 mg/g in neutral water at 30 °C.•The adsorption capacity for Congo red dye reaches the level of carbon materials.•Kinetic and thermodynamic parameters, as well as adsorption mechanism are given.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Ultraviolet B (UVB) rays exposure causes skin inflammation and pigmentation lead to decrease skin lightness. Corncobs (Zea mays) contain flavonoids which can act as antioxidant to prevent free ...radicals and protect the skin pigmentation. This study aimed to evaluate the protective effect of corncob extract cream on skin pigmentation exposed to UVB rays. This pre-posttest control group study was applied to 25 guinea pigs (Cavia porcellus sp) randomly divided into five groups. Corncob extract cream was given every day 20 min before and 4 h after UVB exposure. The UVB exposure total dose was 780 mJ/cm2. Mexameter examination was carried out on the 1st day and 28th day after treatment. There were significantly differences in the lightness level and the mean melanin index (MI) difference of guinea pigs before and after intervention on various groups (p<0.05). No significantly different of the MI between pre- and post-treatment was observed on normal control group (0.22) and negative control group (-1.06) (p>0.05). However, significantly different of the MI was observed on positive control group (-4.01), corncob 40% group (-2.72), and corncob 30% group (-2.03) (p<0.05). In conclusion, corncob extract cream can inhibit the skin pigmentation due UVB rays exposure.
The present study reports the production of Trichoderma viride spores in an earthen vessel using corn cobs. Using 4 kg of corn cobs, spore-based biopesticide was produced after 21 d with a maximum ...spore count of 2.50 × 109 spores/g of substrate and a moisture reduction from 70.80% w/v to 8.10% w/v. The gas chromatography-mass spectrometry analysis of its ethyl acetate extract revealed that it had 20 secondary metabolites, of which 13 were known to be antimicrobial, one was plant growth-promoting, and one performed both functions. Dried extract dissolved in methanol showed the minimum fungicidal concentration of 5–10 mg/ml against Rhizoctonia solani on potato dextrose agar plate. Plate assays and pot experiments on Rhizoctonia solani-infected potato plants exhibited good antifungal and plant growth-promoting activities. The biopesticide showed 71.28% viability over 10 m of storage in the same earthen vessel at 30 ± 2 °C. Thus, a simple, robust technology was developed with good potential for farm deployment.
Display omitted
•Corn cobs in polyethylene bag produced highest T. viride spores than other wastes.•Dry biopesticide from earthen vessel had 2.1-fold more spores as polyethylene bag.•Extract abundant in antimicrobial metabolites inhibited R. solani at 6–10 mg/ml.•Biopesticide proved effective antifungal and plant growth-promoting properties.•Spores showed 71% survivability after 10 m of storage in an earthen vessel.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Biodiesel is produced by transesterification reaction of oils catalyzed by homogeneous catalysts, with the latter being non-recoverable and promoter of solubility of the produced glycerol into the ...otherwise immiscible ester phase, which have to be purified. The need for purification of products is eliminated if heterogeneous catalysts are employed, with the added advantage of the catalyst recovery, however, with disadvantage of requiring drastic reaction conditions (elevated temperatures and pressures, longer reaction times) significantly increasing the costs of production. To overcome such problems, several catalysts were developed, with the sulfonated ones being the most prospective for industrial applications. Thus, the objective herein was to develop a sulfonated heterogeneous catalyst using activated carbon produced from corncobs as precursor material and employ it in microwave-assisted transesterification reactions of soybean oil with ethanol. The optimum operational conditions employed for the reaction were microwave variable power of 0–600 W, catalyst-to-oil mass ratio of 20%, alcohol-to-oil molar ratio of 6:1 and reaction time of 20 min. The catalyst successfully catalyzed the transesterification reaction in times as short as 20 min, resulting in a pure biodiesel phase with yield of 88.7%. The catalyst was reused in five subsequent reaction cycles without loss of its catalytic activity.
•Sulfonated heterogeneous catalyst for transesterification of oils was prepared and employed.•Catalyst was prepared using corncob activated carbon as precursor material.•Microwave-assisted reaction promoted significant reduction in reaction time.•Prepared catalyst did not lose any activity upon reuse in 5 subsequent reaction cycles.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Corn cobs (CCs) are abundant xylan-rich agricultural wastes. Here, we compared CCs XOS yields obtained via two different pretreatment routs, alkali and hydrothermal, using a set of recombinant endo- ...and exo-acting enzymes from GH10 and GH11 families, which have different restrictions for xylan substitutions. Furthermore, impacts of the pretreatments on chemical composition and physical structure of the CCs samples were evaluated. We demonstrated that alkali pretreatment route rendered 59 mg of XOS per gram of initial biomass, while an overall XOS yield of 115 mg/g was achieved via hydrothermal pretreatment using a combination of GH10 and GH11 enzymes. These results hold a promise of ecologically sustainable enzymatic valorization of CCs via “green” and sustainable XOS production.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
•SSF processes with and without prehydrolysis for ethanol production is reported.•Prehydrolysis steps do not significantly impact on the yield in SSF process.•Microaerophilic culture ...conditions enhanced cell growth and bioethanol production.
This study investigates the simultaneous saccharification and fermentation (SSF) process for bioethanol production from corn cobs with prehydrolysis (PSSF) and without prehydrolysis (OSSF). Two response surface models were developed with high coefficients of determination (>0.90). Process optimization gave high bioethanol concentrations and bioethanol conversions for the PSSF (36.92 ± 1.34 g/L and 62.36 ± 2.27%) and OSSF (35.04 ± 0.170 g/L and 58.13 ± 0.283%) models respectively. Additionally, the logistic and modified Gompertz models were used to study the kinetics of microbial cell growth and ethanol formation under microaerophilic and anaerobic conditions. Cell growth in the OSSFmicroaerophilic process gave the highest maximum specific growth rate (µmax) of 0.274 h−1. The PSSFmicroaerophilic bioprocess gave the highest potential maximum bioethanol concentration (Pm) (42.24 g/L). This study demonstrated that microaerophilic rather than anaerobic culture conditions enhanced cell growth and bioethanol production, and that additional prehydrolysis steps do not significantly impact on the bioethanol concentration and conversion in SSF process.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Heavy metals are principal concomitant pollutants in industrial wastewaters, posing a serious threat to public health and the environment. Herein, we develop a novel strategy to produce a ...new nanocomposite formed from corn cobs (CCs) and magnetite as a nanomaterial for the simultaneous removal of Fe
+2
and Ni
+2
. The as-prepared nanocomposite was systematically characterized by x-ray diffraction, field emission scanning electron microscopy, mapping, energy-dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, selected area electron diffraction, zeta size, and zeta potential. Compared to the CCs and Fe
3
O
4
, the nanocomposite showed better adsorption performance. The maximum adsorption efficiency of the CC, Fe
3
O
4
, and the nanocomposite was calculated by atomic analysis to be around 91.84%, 91.28%, and 98.51%, respectively, under the same conditions. This study indicates that the nanocomposite could be a favorable biomass-derived adsorbent for the simultaneous removal of heavy metals.
A comprehensive study was carried out to assess the efficiency of different chemicals on the pretreatment of plant biomass, corn cobs. The efficiency was assessed based on its effect on subsequent ...hydrolysis of biomass for the conversion to fermentable sugars. Both alkali- and acid-based pretreatments were carried out under optimized conditions to avoid the formation of inhibitors and also to yield more sugars. Among the different chemicals used, 2% NaOH (w/v) was found to be effective with the delignification efficiency of 84.32%, and furthermore, the biomass saccharification efficiency was found to be 86.28% using 1.20% (v/v) HNO
3
at 100°C for 90 min, whereas the pretreatment with other chemicals such as KOH, NaClO
2
, Na
2
SO
3
, and NH
3
had significantly (
p
< 0.05) low delignification, which ultimately reduced the saccharification efficiency. In acid–base-based pretreatment, 1.5% (v/v) HNO
3
resulted in 63.42% delignification along with 68% digestion of hemicelluloses. The effect of pretreatment efficiency on digestibility was investigated by biomass characterization using SEM, FTIR, and XRD analyses before and after the treatment process. The imaging studies clearly indicated that 2% NaOH efficiently digested the complex matrix alignment and enhanced the surface area of the carbohydrate polymer which had shown a positive impact on the rate of hydrolysis. The study concludes that alkali-based pretreatment is the efficient and cost-viable technique for the effective valorization of corn cobs for the production of fermentable sugars which can be further converted to various valuable bioproducts.
Production of green fuels and chemicals from non-edible corn cob residues presents an excellent opportunity to produce sustainable low carbon energy vectors as an alternative to fossil fuels. The ...objective of this study was to optimize the fuel physical and chemical properties of torrefied corn cobs bio-oil by investigating the relationship between feedstock pre-treatment (torrefaction) temperatures (240, 260, 280 and 300 °C), and subsequent pyrolysis temperatures (400, 450, 500 and 550 °C). This experimental methodology aimed to improve both yields and properties of bio-oils from corn cobs. Torrefaction was first carried out as a pre-treatment step using a custom-built torrefaction reactor followed by pyrolysis using a continuous fluidized bed reactor. Torrefaction was found to be a promising pre-treatment step because it had the effect of reducing the water content and viscosity within the bio-oil. Corn cobs grinding energy requirements could be reduced by 69% when torrefaction was applied from 240 °C to 260 °C. A maximum bio-oil yield of 51.7% was achieved when the optimal temperatures (torrefaction 260 °C and pyrolysis 450 °C) was applied. Overall, using torrefaction as a pre-treatment step before pyrolysis was shown to be a promising approach for improving some physiochemical properties of bio-oil for its application as a fuel.
Display omitted
•The effect of torrefaction pre-treatment on pyrolysis of corn cobs was studied.•Corn cob grinding energy is decreased by 69% when torrefaction was applied.•Torrefaction at 260 °C and pyrolysis at 450 °C produced a maximum bio-oil (51.7%).•Coupling torrefaction with pyrolysis achieved a bio-oil with 21 MJ/kg value.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► Corncob was used as a source of cellulose nanocrystals production. ► The reinforcing effect of the nanocrystals was evaluated in PVA polymer matrix. ► Crystallinity influences more the tensile ...properties than the aspects ratio.
Corncob is an agro-industrial waste available in large quantities in several countries, including Brazil, which deserves to be better and/or properly used. This work evaluates the use of corncob as a source of cellulose to obtain nanocrystals by acid hydrolysis in order to obtain a material suitable to be a reinforcement agent in the manufacture of nanocomposites. The hydrolysis was performed at 45°C for 30, 60 and 90min, using 15mL of H2SO4 (9.17M) for each gram of cellulose. The resulting cellulose nanocrystals of corncob (CNC) were characterized by crystallinity index, morphology and thermal stability, and their reinforcing capability was evaluated using polyvinyl alcohol (PVA) as the polymeric matrix. Among the hydrolysis conditions carried out, the extraction time of 60min resulted in nanoparticles (CNC60) with larger reinforcing capability. The CNC60 endowed the CNC/PVA composites with a significantly improved tensile strength of 140.2% when only 9% (wt.%) CNC60 was incorporated. The CNC60 presented a needle-shaped nature, high crystallinity (83.7%), good thermal stability (around 185°C), an average length (L) of 210.8±44.2nm and a diameter (D) of 4.15±1.08nm, giving an aspect ratio (L/D) of around 53.4±15.8. The results show that the more suitable filler was CNC60. Since CNC60 has the highest crystallinity among the CNC samples, but does not have the highest aspect ratio, these results suggest that the difference in the crystallinity index has a greater influence on the tensile properties than the aspects ratio, in this case. Cellulose nanocrystals obtained from corncob have great potential as reinforcing agents for the manufacture of nanocomposites.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
PDF