In this work, the effect of purple sugarcane (Saccharum officinarum) peel anthocyanin extracts (PSPAEs) on the physical and functional properties of films based on lemon peel waste pectin (LPP) was ...investigated for the first time. PSPAEs have great compatibility with LPP matrix, and the LPP/PSPAEs composite film demonstrated a higher ultraviolet light barrier capacity. The incorporation of PSPAEs significantly improved the physical properties of LPP films confirmed by the enhanced mechanical properties and thermal stability, which might be associated with the more compact structure observed by scanning electron microscope images and possible intermolecular interaction such as hydrogen bond interactions between film components demonstrated via Fourier transform infrared spectra and X-ray diffraction analysis. Furthermore, PSPAEs imparted excellent functional properties on LPP films, including antioxidant properties and sensitive color response to the pH alternation and ammonia atmosphere, which favored the possible application in monitoring food freshness. Herein, LPP/PSPAEs films were employed to detect the freshness of shrimp and beef, and a visually discernible color change could be observed as the food turned from fresh to stale. In addition, the LPP/PSPAEs composite films displayed great biodegradability in the soil. The results showed that could impart excellent properties on LPP films, and LPP/PSPAEs composite film is a promising biodegradable film that can be used for intelligent detection of food freshness.
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•Films based on lemon peel waste pectin (LPP) were prepared.•Purple sugarcane peel anthocyanin extracts (PSPAEs) were added into LPP films.•20–30% PSPAEs improved mechanical properties and thermal stability of LPP films.•PSPAEs effectively imparted excellent functional properties on LPP films.•LPP/30% PSPAEs composite films showed promise for the detection of food freshness.
Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb
2+, Cd
2+ and Ni
2+ ions from aqueous solution using the grafted copolymerization-modified orange peel ...(OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb
2+, Cd
2+ and Ni
2+ ions were 476.1, 293.3 and 162.6
mg
g
−1, respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb
2+, Cd
2+ and Ni
2+, respectively. The kinetics for Pb
2+, Cd
2+ and Ni
2+ ions biosorption followed the pseudo-second-order kinetics. The free energy changes (Δ
G°) for Pb
2+, Cd
2+ and Ni
2+ ions biosorption process were found to be −3.77, −4.99 and −4.22
kJ
mol
−1, respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb
2+, Cd
2+ and Ni
2+ ions from the biosorbent was effectively achieved in a 0.05
mol
L
−1 HCl solution.
In this study, carrageenase immobilization was evaluated with a concise and efficient strategy. Pomelo peel cellulose (PPC) modified by polyethyleneimine (PEI) using the physical absorption method ...was used as a carrier to immobilize carrageenase and achieved repeated batch catalysis. In addition, various immobilization and reaction parameters were scrutinized to enhance the immobilization efficiency. Under the optimized conditions, the enzyme activity recovery rate was more than 50% and 4.1 times higher than immobilization with non-modified pomelo peels. The optimum temperature and pH of carrageenase after immobilization by PEI-modified pomelo peel, at 60°C and 7.5 respectively, were in line with the free enzyme. The temperature resistance was reduced, inconsistent with free enzyme, and pH resistance was increased. A significant loss of activity (46.8%) was observed after reusing it thrice under optimal reaction conditions. In terms of stability, the immobilized enzyme conserved 76.0% of the initial enzyme activity after 98 days of storage. Furthermore, a modest decrease in the kinetic constant (K m ) value was observed, indicating the improved substrate affinity of the immobilized enzyme. Therefore, modified pomelo peel is a verified and promising enzyme immobilization system for the synthesis of inorganic solvents.
Fruit peels, also known as rinds or skins, are wastes readily available in large quantities. Here, we have used pineapple (PA) and watermelon (WM) peels as substrates in the culture media (containing ...5 % sucrose and 0.7 % ammonium sulfate) for production of bacterial cellulose (BC). The bacterial culture used in the study, Komagataeibacter hansenii produced BC under static conditions as a pellicle at the air–liquid interface in standard Hestrin and Schramm (HS) medium. The yield obtained was ~3.0 g/100 ml (on a wet weight basis). The cellulosic nature of the pellicle was confirmed by CO₂, H₂O, N₂, and SO₂ (CHNS) analysis and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the pellicle revealed the presence of flat twisted ribbonlike fibrils (70–130 nm wide). X-ray diffraction analysis proved its crystalline nature (matching cellulose I) with a crystallinity index of 67 %. When K. hansenii was grown in PA and WM media, BC yields were threefolds or fourfolds higher than those obtained in HS medium. Interestingly, textural characterization tests (viz., SEM, crystallinity index, resilience, hardness, adhesiveness, cohesiveness, springiness, shear energy and stress, and energy required for puncturing the pellicle) proved that the quality of BC produced in PA and WM media was superior to the BC produced in HS medium. These findings demonstrate the utility of the newly designed media for getting higher yields and better quality of BC, which could make fermentative production of BC more attractive on a commercial scale.
This study investigated the removal of hexavalent chromium (Cr(VI)) in aqueous solutions using pomelo peel (PP) and FeCl3-modified pomelo peel (FPP) as novel biomass adsorbents. Batch adsorption ...experiments were performed to evaluate the effects of pH, time, temperature, initial concentration, and adsorbent dose on Cr(VI) removal by PP and FPP. The results show that the maximum adsorption capacity of Cr(VI) was 21.55 mg/g for FPP and 0.57 mg/g for PP at a pH of 2.0 and a temperature of 40°C. The surface shape, microstructure, and chemical composition of FPP were analyzed with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectroscopy (EDS), and compared with those of PP. The results show that the adsorption performance of FPP was much better than that of PP, indicating that FPP can be an alternative high-efficiency adsorbent for Cr(VI) removal.
A pH-sensitive intelligent indicator film was developed and used for monitoring dynamic changes in chicken freshness at 4 °C and 25 °C by immobilizing 0.2 %–1.0 % purple sweet potato peel extracts ...(PPE) with sodium alginate (SA). The films presented a wide range of colors from red-pink to green-yellow at 2–13, and the films with less PPE were more sensitive to ammonia. The color of films with 0.6 % PPE changed from pink to blue when used in monitoring chicken freshness at 4 °C (5 d) and 25 °C (60 h), which corresponded to changes in total volatile base nitrogen from 5.35 (5.35) mg/100 g to 16.2 (19.9) mg/100 g. Scanning electron microscopy and X-ray diffraction revealed that PPE improved the compactness and crystallinity of SA films, while Fourier transform infrared spectroscopy revealed hydrogen bonds between SA and PPE. Compared to SA films, the water vapor and light barrier abilities of films with 0.6 % were significantly improved (P < 0.05), there was no significant effect on tensile strength (P > 0.05), and the elongation of 0.6 % PPE films (P < 0.05) was decreased. Thus, PPE can serve as an excellent indicator of intelligent films for monitoring the freshness of meat products.
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•Purple sweet potato peel extracts (PPE) served as an indicator of intelligent film.•Sodium alginate (SA) and PPE films had excellent sensitivity to pH (2–13) and NH3.•Hydrogen bonds were main interaction force between the SA chains and PPE.•Monitoring ability of SA-PPE6 film in chicken freshness under 4 °C/5 d and 25 °C/60 h was obvious.•There was a positive correlation between chicken storage freshness and films color.
Removal of tetracycline antibiotics (TCs) by biochar adsorption is emerging as a cost-effective and environmentally friendly strategy. This study developed a novel pomelo peel derived biochar, which ...was prepared at 400 °C (BC-400) and 600 °C (BC-600) under nitrogen conditions. To enhance the adsorption capacity, BC-400 was further activated by KOH at 600 °C with a KOH: BC-400 ratio of 4:1. The activated biochar (BC-KOH) displayed a much larger surface area (2457.37 m2/g) and total pore volume (1.14 cm3/g) than BC-400 and BC-600. High adsorption capacity of BC-KOH was achieved for removing tetracycline (476.19 mg/g), oxytetracycline (407.5 mg/g) and chlortetracycline (555.56 mg/g) simultaneously at 313.15 K, which was comparable with other biochars derived from agricultural wastes reported previously. The adsorption data could be fitted by the pseudo-second-order kinetic model and Langmuir isotherm model successfully. The initial solution pH indicated the potential influence of TCs adsorption capacity on BC-KOH. These results suggest that pore filling, electrostatic interaction and π–π interactions between the adsorbent and adsorbate may constitute the main adsorption mechanism. BC-KOH can be used as a potential adsorbent for removing TCs from swine wastewater effectively, cheaply and in an environmentally friendly way.
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•Pomelo peel derived biochar was effective for removing tetracycline antibiotics.•KOH activation largely enhanced the surface area and pore size of the biochar.•Adsorption capacity was positive with biochar's surface area and pore size.•Adsorption capacity of BC-KOH was comparable to other wastes derived biochar.•Pore-filling, electrostatic and π–π interaction contributed to the adsorption process.
Unique zerovalent iron (Fe0) supported on biochar nanocomposite (Fe0-BRtP) was synthesized from Nephelium lappaceum (Rambutan) fruit peel waste and were applied for the simultaneous removal of 6 ...selected organochlorine pesticides (OCPs) from aqueous medium. During facile synthesis of Fe0-BRtP, Rambutan peel extract was used as the green reducing mediator to reduce Fe2+ to zerovalent iron (Fe0), instead of toxic sodium borohydride which were used for chemical synthesis. For comparison, chemically synthesized Fe0-BChe nanocomposite was also prepared in this work. Characterization study confirmed the successful synthesis and dispersion of Fe0 nanoparticles on biochar surface. Batch experiments revealed that Fe0-BRtP and Fe0-BChe nanocomposites combine the advantage of adsorption and dechlorination of OCPs in aqueous medium and up to 96–99% and 83–91% removal was obtained within 120 and 150 min, respectively at initial pH 4. Nevertheless, the reactivity of Fe0-BChe nanocomposite decreased 2 folds after being aged in air for one month, whilst Fe0-BRtP almost remained the same. Adsorption isotherm of OCPs were fitted well to Langmuir isotherm and then to Freundlich isotherm. The experimental kinetic data were fitted first to pseudo-second-order adsorption kinetic model and then to pseudo-first-order reduction kinetic model. The adsorption mechanism involves π-π electron-donor-acceptor interaction and adsorption is facilitated by the hydrophobic sorption and pore filling. After being reused five times, the removal efficiency of regenerated Fe0-BChe and Fe0-BRtP was 5–13% and 89–92%, respectively. The application of this Fe0-BRtP nanocomposite could represent a green and low-cost potential material for adsorption and subsequent reduction of OCPs in aquatic system.
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•Fe0-Biochar nanocomposites were synthesized using Nephelium lappaceum peel waste.•Morphology of Fe0-BRtP and Fe0-BChe nanocomposites was explored.•Six organochlorine pesticides removed involving adsorption and reduction mechanism.•Lower reactivity of aged Fe0-BChe nanocomposite, while Fe0-BRtP remained the same.•Regenerated Fe0-BRtP possesses good reusability even after five cycles.
Adsorption isotherm of OPP–Cd
2+, MNP–Cd
2+ and MNP–OPP–Cd
2+.
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► A novel low cost MNP–OPP was developed for cadmium removal from aqueous solutions. ► Superior efficiency and kinetics ...were demonstrated as compared to parent adsorbents. ► Cadmium removal result from simulated electroplating industry effluent is promising. ► Desorption and reusability without loss of efficiency showed its practical utility. ► Additional benefits like easy synthesis, recovery, and environmental friendliness.
An agricultural waste-orange peel powder (OPP) was successfully modified into a novel magnetic nano-adsorbent (MNP–OPP) by co-precipitating it with Fe
3O
4 nanoparticles (MNP) for cadmium ion removal from aqueous solutions. Characterization of MNP–OPP by FTIR, SEM, XRD, TEM and VSM revealed the covalent binding of hydroxyl groups of MNP with the carboxyl groups of OPP, and further confirmed its physico-chemical properties favorable for metal binding. The cadmium adsorption onto MNP–OPP, MNP and OPP was tested under different pH, ionic strength, natural organic matter, adsorbate concentration, contact time and temperature conditions. Results revealed a faster kinetics and efficiency of MNP–OPP in comparison to those of MNP and OPP and further confirmed a complexation and ion exchange mechanism to be operative in metal binding. The adsorption equilibrium data obeyed the Langmuir model and the kinetic data were well described by the pseudo-second-order model. Thermodynamic studies revealed the feasibility and endothermic nature of the system. Breakthrough capacity from column experiments, adequate desorption as well as reusability without significant loss of efficiency established the practicality of the developed system. Cadmium removal was achieved at 82% from a simulated electroplating industry wastewater. The experimental results reveal the technical feasibility of MNP–OPP, its easy synthesis, recovery, economic, eco-friendly and a promising advanced adsorbent in environmental pollution cleanup.
In line with the growing demand for green alternatives to conventional petroleum-derived plastic packaging, fully bio-based and biodegradable biocomposites were developed for this work, for the ...purpose of packaging dry foods, following the principles of circular economy. Solutions of plasticized chitosan (pCS) were blended with varying amounts of hydrolyzed orange peel (hOP) waste to produce films by casting. The hydrolytic pretreatment of orange peels enabled the creation of biocomposites containing up to 80 wt% hOP, while the formulation with 70 wt% hOP had the best general performance. Chemical characterization of the developed films revealed that chitosan molecules interact electrostatically with pectin molecules in hOP. The strong interaction between chitosan and pectin molecules results in improved mechanical, barrier, and thermal properties of the composite materials compared to their individual components. In addition, the biocomposites exhibit improved water resistance due to their reduced water solubility compared to chitosan and hOP films. The migration of the films’ components in the food simulant Tenax was evaluated, and the results revealed low values, compliant with the current EU regulation. However, due to the electrostatic interactions, the films lost the antimicrobial activity of the individual components, chitosan and hOP, against E. coli and S. aureus bacteria, a property that could turn the developed films into active packaging. Finally, the optical and antioxidant properties and the biodegradability in soil of the developed films were also assayed, showing high transparency, antioxidant capacity, and fast biodegradability, reaching 62.9% weight loss after 26 days of the experiment.
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•Plasticized chitosan (pCS) was blended with hydrolyzed orange peel (hOP) waste.•The hydrolysis of orange peels allowed to obtain biocomposites with up to 80 wt% hOP.•hOP improved mechanical, barrier, water resistance and thermal properties of pCS.•The antimicrobial activity of the separate components was lost when hOP and pCS were combined.•Biocomposites showed high transparency, antioxidant capacity, and fast biodegradability.
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