Waste Lemon Research Articles

Hydrothermal synthesis of Gd-doped CaO nanoparticles from lemon peel extract for efficient photocatalytic degradation of methylene blue under UV and sunlight

Water pollution, exacerbated by the improper disposal of non-biodegradable dyes from textile and paper industries, poses a significant global threat. Addressing this challenge, the present study focuses on the photocatalytic degradation of methylene blue (MB), a harmful azo dye, using novel Gd-doped CaO NPs synthesized with waste lemon peel extract (LPE) as a green stabilizing agent. The CaO NPs, calcined at 700 °C and subsequently doped with gadolinium (Gd) at concentrations of 2, 4, and 6 mmol via hydrothermal method, were characterized using various techniques. Fourier Transform Infrared Spectroscopy (FTIR) confirmed presence of Ca-O and Gd-O with the bond lengths of 1.7 Å and 1.2 Å, respectively. UV–Visible spectra revealed a bandgap in the range of 3.28 to 2.50 eV. X-ray Diffraction (XRD) patterns confirmed crystallinity with the crystallite size estimated using the Scherrer and William sons-Hall (W-H) methods ranging from 18 to 38 nm and XRD deduced specific surface area between 47 and 98 m2/g. Dynamic Light Scattering (DLS) showed particle size distribution from 38 to 130 nm, and zeta potential values ranging from −13.5 to −19.9 mV. The photocatalytic activity against MB was tested under UV light and natural sunlight at dye concentrations of 10, 15, and 20 ppm. The 4 mmol Gd-doped CaO NPs achieved a remarkable 98 % degradation efficiency within 2 h of sunlight exposure at a 10 ppm dye concentration. The degradation followed a pseudo-first-order reaction, and a possible degradation pathway was proposed for methylene blue. This study concludes that Gd-doped CaO NPs are highly effective, sustainable, and cost-efficient photocatalysts for wastewater treatment.

Isolation And Identification of Bacteria Associated With Bioelectricity Generation From Fruit Wastes And Gutter Sludge Using Microbial Fuel Cells (MFC) In Kano Metropolis, Kano State, Nigeria

Bioelectricity generation is another environmentally friendly mean of waste management, commonly carried out using microbial fuel cell (MFC) technology. The present work aims to generate bioelectricity from the fruit wastes using microbial fuel cells (MFC) technology and to isolate and identify bacteria during bioelectricity production. Fruit samples from different fruit wastes of banana, lemon, orange, water melon and pawpaw were collected from Na’ibawa-Yanlemo fruit market’s dump site in Kano metropolis, Kano State Nigeria. Physicochemical parameters such as biological oxygen demand (BOD), chemical oxygen demand (COD), total carbon (TC), total nitrogen (TN), organic matter (OM), Temperature and pH of slurries of individual and mixed fruit wastes were determined. Biochemical tests such as voges-proskauer test, oxidase test, catalase test, citrate test and sugar fermentation (TSI) test was also carried out using standard procedures. Generation of bioelectricity was monitored and recorded within a constructed seven dual chambered microbial fuel cells (MFCs) with wasted fruit as readily available materials. Current, current density, power and power density produced from different waste samples for twenty days was also recorded as bioelectricity generated from microbial fuel cells. Bacterial counts at the beginning and end of bioelectricity generation was also recorded from different fruits waste samples for microbial fuel cells (MFCs). The result of pH mean value of slurries of individual fruits is recorded to be all acidic with lemon having the highest acidity recorded as 3.45±0.62. The pH mean value of the mixed fruit was recorded as7.1±0.23. Waste pawpaw fruit had 6±0.62 % the percentage of organic matter among all the individual waste fruits while the mixed fruit combined had 10±0.62 % mean value of percentage organic matter (OM). Two (2) bacterial genera were biochemically identified as Klebsiella pneumoniae and Esherichia coli. The highest generation of voltage (mV) from microbial fuel cells was achieved from gutter, mixed fruit and orange as 650, 400 and 390 mV respectively. The peak highest current produced was achieved from orange waste samples as 0.7mA/m2 at day fourteen. Waste lemon had the highest colony count among all the fruits at the beginning and end of the bioelectricity generation of 2.2×103 and 4.12×102 respectively. Mixed fruits had the colony count of 2.10×105 and 7.20×103 at the beginning and end respectively.

Exploring eco-friendly solutions for Phytophthora disease management: Harnessing the anti-oomycete potential of a fermented lemon waste formulation

Phytophthora species pose significant challenges to agricultural and natural ecosystems due to their ecological plasticity and ability to cause diseases of various plant species. Effective control of Phytophthora diseases requires integrated approaches that consider specific agronomic practices, environmental factors, and the rationale use of chemicals. In response to the need for eco-friendly alternatives, this study investigated the anti-oomycete potential of a formulation derived from the fermentation of lemon wastes by Lactiplantibacillus plantarum ('bioact-LM'). In vitro assays demonstrated the significant anti-oomycete efficacy of bioact-LM against multiple Phytophthora species, both through direct contact inhibition and the release of volatile organic compounds (VOCs). In vivo assessments on orange and apple fruits further confirmed the effectiveness of bioact-LM in reducing Phytophthora rot severity. These findings suggest bioact-LM is promising as a sustainable alternative to synthetic fungicide for Phytophthora disease management, highlighting the importance of exploring eco-friendly solutions in a scenario of environmental challenges and restriction in the use of conventional chemical control methods.

GREEN EXTRACTION OF CAROTENOIDS FROM LEMON PEELS

Nowadays, there is a growing interest in fully utilizing agro-industrial wastes, with carotenoids gaining attention as valuable coloring agents. One of the potential sources for carotenoid extraction is lemon peel. The purpose of this study was to determine optimal extraction techniques for extracting as much carotenoids as possible from lemon peel. In this context, a comparison was conducted among extracts obtained via conventional, ultrasound-assisted (UAE), and ultrasound-assisted enzymatic (UAEE) extraction methods. The highest carotenoid content (0.792±0.01 mg/L) was achieved with UAEE, while the lowest (0.493±0.01 mg/L) was obtained conventionally. UAEE exhibited the highest antioxidant activity values among three methods: 753.80±5.79 mg TE/L (ABTS), 624.64±10.52 mg TE/L (DPPH), and 186.64±1.66 μmol TE/L (FRAP). In conclusion, UAEE showed promise in extracting carotenoids from lemon peel. Thus, by carotenoid extraction using green technology from waste lemon peels, with higher added value, richer in terms of phenolic composition and antioxidant properties, has been obtained.

WASTE LEMON PEEL AS A CIRCULAR SOLUTION FOR THE REMEDIATION OF LEAD-CONTAMINATED SLUDGE FOR LAND APPLICATION

Lead-contaminated sludge is a major environmental concern, as land application of this material can contaminate surfaces with toxic heavy metals. To address this, a novel approach to utilizing waste lemon peel (WLP) for the remediation of lead-contaminated sludge for land application with the circular economy in perspective is presented. The WLP was collected from local producers and characterized using Fourier transform infrared (FTIR) spectroscopy to determine the functional groups present. The hydroxyl, carboxyl, ether, and amide groups are the main functional groups in the sample and they have been identified as potential sites responsible for binding heavy metal ions to the biomass.
 The sludge samples were collected from the Ahmadu Bello University Water treatment plant and analyzed for contamination. The effects of WLP on the lead sorption were investigated using batch experiments. The results indicated that lead sorption onto the WLP was significantly as high as 90.5%. The WLP was found to effectively reduce the lead from the contaminated sludge. This study aimed to identify the capability of WLP as a low-cost and sustainable material for the remediation of lead-contaminated sludge for land application, indicating the potential for waste materials to be utilized in the circular economy. The Material Circularity Indicator of 0.835 indicated a highly circular system.

Study of combined drying of lemon seeds and peel

The aim of the paper is to study the process of combined drying of lemon waste and to substantiate the prospects for the implementation of the process of drying lemon waste using IR-convective heat supply to intensify moisture transfer due to preliminary IR treatment with powerful pulsed radiation. As a result of theoretical and experimental studies, the modes of IR-convective drying have been determined by studies. The influence of the heat flux emitted by IR lamps on the object of study has been studied, depending on the variation of the increase in heat flux in the size of the distribution of emitters, respectively, lemon peel and seeds, processing time. Analyses have shown that in the proposed method, when exposed to IR rays, intensive removal of moisture from the entire volume of the material occurs.

Fabrication and characterization of ADC-12 hybrid composites utilizing lemon grass ash and boron nitride through stir-squeeze casting method

In recent years, there has been increased interest in hybridizing metal matrix composites using agro-based-waste materials as sustainable choices. Despite the poor tribo-mechanical properties of conventional reinforcement materials, there is immense potential for using alternate reinforcing elements to enhance the mechanical features of matrix composite. In addition, conventional casting procedures present several challenges, including high costs and a lack of adequate mechanical qualities in the finished product. To combat these issues, the authors herein produce the well-known aluminium matrix composite (AMC), ADC 12 alloy, using waste lemon grass (LG) ash at a fixed rate (6 wt%) and hexagonal Boron Nitride (hBN) at variable proportions (0, 1.5, 3, 4.5, and 6 wt%) as reinforcing element against traditional reinforcement particles to enhance the tribo-mechanical properties of casted hybrid AMC. In addition, the Stir-Squeeze Casting method produces the hybrid AMC, dramatically decreasing production costs and enhancing final product qualities. The hybrid AMC formed by Stir-Squeeze Casting is examined for its mechanical, corrosion, and tribological characteristics, with the findings indicating that the addition of LG and hBN improved the mechanical, corrosion, and tribological properties of the ADC-LG-hBN composites, with 6 wt% LG and 4.5 wt% hBN reinforcements producing the optimal result. The experimental density of ADC-LG- hBN composites was reduced by 8% when compared to the ADC 12 alloy, while the composites’ tensile, hardness and compressive strength were increased by 118.9%, 36.7%, and 33.6%, respectively. Similarly, the developed composite showed an improved corrosion resistance of 43.8% for 24 h, and the wear rate decreased by 90.4%.

Potential Effect of Lemon Peel Oil with Novel Eco-Friendly and Biodegradable Emulsion in Un-Modified Diesel Engine.

The current research work is based on exploring a novel biological fuel source and renewable fuel offered by waste lemon fruit skin. Furthermore, bio-based multi-wall carbon nanotubes (BMWCNTs), emulsion, fossil diesel, and raw lemon peel oil were procured. The single-cylinder diesel engine was evaluated using these potential ingredients in terms of performance, combustion, and emission. Test engine results reveal that the presence of BMWCNT emulsion in the bio-fuel + blend + emulsion blend produced a lower (4.7%) brake thermal efficiency (BTE) and a higher (13.6%) brake-specific energy consumption (BSEC) at peak engine load conditions with diesel. The same test fuel blend possesses an equivalent heat release rate (HRR) and cylinder pressure trends to the diesel fuel blend due to an optimized air/fuel mixture and oxygen supply. Bio-fuel + blend + emulsion achieved step-down reductions of 7.83% carbon monoxide (CO) and 20.68% hydrocarbon (HC) emissions, as well as reductions of 27.7% nitrogen oxide (NOx) and 37.3% smoke emissions at peak engine load with diesel.

Host-Guest Complexes HP-β-CD/Citrus Antioxidants: Exploratory Evaluations of Enhanced Properties in Biodegradable Film Packaging.

The aim of this work was to exploit the antioxidant potential of molecules recovered during the pectin purification process of citrus lemon waste and to encapsulate them in stable pectin films, with a view to a green and circular economy process. Antioxidant molecules were recovered during the pectin purification process, further recovering matter from the waste. Seven molecules were identified and quantified, and the antioxidant power of the mixture and its stability over time was evaluated. To improve the stability of the bioactive fraction, this was complexed with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD); indeed, this procedure increased their thermal stability from 120 °C up to 250 °C, as verified by thermogravimetry. Furthermore, the most promising complexes were studied under autoclave-like conditions (120 °C, 28 min) to simulate thermal sterilization. The antioxidants and HP-β-CD were combined in a pectin film, showing increased stability over time (up to three times) compared to uncomplexed antioxidants. This process represents a first step towards the development of applicable devices for the delivery of antioxidant molecules.

RECOVERY OF HESPERIDIN FROM LEMON BY-PRODUCTS USING GREEN TECHNIQUES

The food industry is the main producer of food waste. Therefore, the development of methodologies to reuse and make the most of it is of great interest. Food industry waste can contain compounds with added value that, if properly extracted and used, can be applied to the development of healthy foods (clean label), nutraceuticals, senior food, cosmetics, etc. The revaluation of by-products from the citrus industry will make it possible to reduce the large volume of lemon waste, reducing the cost of waste management and obtaining compounds of interest from them. In this work, different alternative methodologies to the use of organic solvents have been used for the extraction of Hesperidin in lemon by-products, including thermal, enzymatic and ultrasound treatment and purification adsorption processes with resins, granular activated carbon and zeolite were optimized. The optimum Hesperidin extraction (86371 ± 422 mg GAE/g dry extract) was achieved using an enzymatic pre-treatment, cellulase enzyme (Validase TRL®-Sigma) at 0.01% of weight of the lemon peel by-product, treatment time of 60 min, and water/citrus by-product ratio of 3:1 w/w, followed by a purification adsorption/desorption process through Purolite PAD610 resin.

One-step green synthesis of meso-microporous carbons by self-activation of lemon wastes for high-performance supercapacitors

A green self-activating system is introduced for the synthesis of porous carbons. This system is introduced to overcome the environmental concerns regarding the harmful by-products of the conventional synthesis approaches. The introduced system is based on the circulating active gases, released during the carbonization treatments at T ≤ 500 °C. These active gases are stored in the system and participate in the activation process at T ≥ 700 °C. During the activation process, there is no exhaust gas and any need for a protective atmosphere. Lemon wastes were pyrolyzed in this system at several temperatures (400 to 900 °C). It is demonstrated that the introduced system is applicable for the synthesis of turbostratic carbons with relatively high graphitization levels. Pyrolyzation at T ≥ 800 °C can appropriately activate the lemon biomass. The prepared meso-microporous carbon has a large specific surface area of up to 2111 m2.g−1 and a pore volume of 1.28 cm3.g−1 can be obtained after pyrolyzation at 900 °C. Meso-microporous carbon are applied as an electrode for supercapacitors. The prepared supercapacitor performs an electric double layer with minor pseudo-capacitance behavior. The supercapacitor illustrates the capacitance of 254 F.g−1 at 10 A.g−1 and excellent stability of 92 % retention after 30,000 cycles.

Citrus limetta Peel-Derived Catalyst for Sustainable Production of Biodiesel.

To produce biodiesel from oleic acid (OA), the effectiveness of sweet lemon (Citrus limetta) waste peels as an acidic catalyst in an esterification process is examined in the current work. A biowaste-derived sulfonated carbon-based catalyst is fabricated without high temperatures via a simple one-pot process. Several techniques are used to investigate the chemical components and morphology of the catalyst, including Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and N2 adsorption–desorption. The biodiesel conversion is observed by gas chromatography–mass spectrometry (GC–MS), proton nuclear magnetic resonance 1H NMR, and carbon nuclear magnetic resonance 13C NMR. The excellent biodiesel conversion of 96% was obtained using optimized conditions, i.e., 1:20 of OA/MeOH, 5 wt % catalyst loading, 70 °C temperature, and 3 h. The catalyst shows 87% conversion in just 1 h, and the maximum conversion was found to be ≈96%. This high activity of the catalyst can be attributed to the presence of sulfonic groups and its porous nature. The formed catalyst shows excellent catalytic activity up to three cycles.

Extraction and Characterization of Pectin from Lemon Waste for Commercial Applications

The objective of this paper was preliminary to extract and characterization of purified pectin from lemon wastes. Dry lemon waste was extracted applying citric acid solvent or water at various concentrations under a similar condition (85 ºC for 4 h). It was found that the highest yield of pectin (20.8% dry basis) was achieved using hot water extraction with an esterification degree of 47.8%. It contained 63.2 ± 0.74% galacturonic acid, followed by 17.4 ± 0.76% total sugar. The monosaccharides found in pectin were arabinose (2.7 ± 0.20%), galactose (2.3 ± 0.01%), glucose (1.4 ± 0.09%), mannose (0.4 ± 0.01%), fructose (0.4 ± 0.05%), and xylose (0.1 ± 0.01%). The found pectin had a high atomic weight of 2060 kDa with a wide polydispersity index of 4.41, decided by high-Performance Size Exclusion Chromatography (HPSEC). The extricated lemon waste pectin was grouped into low methoxyl pectin, depends on the methoxyl content and degree of esterification affirmed by Fourier transform infrared spectroscopy (FT-IR) and rheological properties. In conclusion, the discoveries of the study show that lemon waste can be investigated as a promising elective for the commercial manufacturing of pectin.

A new insight on improved biomethanation using graphene oxide from fermented Assam lemon waste

The present study comprises valorization of Assam lemon waste through anaerobic digestion. The uniqueness of the study lies in its process of substituting cow dung with a mixed anaerobic culture (MAC) and in evaluating the effect of graphene oxide (GO) on the fermentation process. A sequential improvement of biomethane yield was observed to be 93.86 ± 0.31, 216.54 ± 1.63, 219.64 ± 0.14 and 231.55 ± 0.27 ml/g VSfed in presence of single variable such as substrate concentration, time, GO and inoculum volume, respectively. Further optimization was carried out adopting central composite design (CCD) based response surface methodology (RSM). The maximum biomethane yield of 243.23 ± 1.99 ml/g VSfed was achieved when the solid loading was kept at 25 g TS/L, 0.06% (w/v) concentration of GO, incubated for 30 days at 37 °C which has resulted into 19.04% enhanced methane yield. Kinetic analysis exhibited lowest deviation with experimental cumulative methane yield, lowest value of λ (4.37 days) and RMSE (5.85) in modified Gompertz model. Digested biomass characterization revealed 18.46% reduction in crystallinity along with a major change in FTIR peaks. Materials and energy flow of the underlying process show 70.88% efficiency of the process with 4.96 kJ/g net energy gain. The report on AD of generated Assam lemon waste to biomethane with the intervention of GO is rare. Thus the result obtained from the current study will encourage the scientific community to improve the biomethane yield by the addition of conductive materials.

Single-step recovery of pectin and essential oil from lemon waste by ohmic heating assisted extraction/hydrodistillation: A multi-response optimization study

The main products obtained from citrus wastes are pectin and essential oil. In this work, ohmic heating assisted extraction/hydrodistillation (OHAE/H) was applied for the simultaneous recovery of pectin and essential oil from lemon waste. Optimum OHAE/H conditions to maximize the yield of pectin and essential oil were determined with response surface methodology. Three independent variables, namely liquid to solid ratio (w:v), extraction/hydrodistillation time (min) and voltage gradient (V/cm) were varied to obtain maximum pectin and essential oil yield. Optimum OHAE/H conditions were determined as 8.7:1 liquid to solid ratio, 58.4 min extraction/hydrodistillation time and 14.2 V/cm voltage gradient. The predicted pectin and essential oil yields at optimum conditions were 16.58 and 3.62 g/100 g lemon waste, respectively. Data analysis showed that all of the independent variables significantly affected the pectin and essential oil yield. In the verification study, close agreement was found between predicted and experimental values. Conventional heating extraction/hydrodistillation (CHE/H) were conducted to evaluate the effectivity of OHAE/H. With OHAE/H process, the yields of the pectin and essential oil were significantly increased when compared to CHE/H. Limonene concentration of the essential oil produced with OHAE/H was higher than the essential oil produced by CHE/H. Results demonstrate that the single-step OHAE/H could be an effective method for simultaneous extraction and hydrodistillation of pectin and essential oils.

In vitro antifungal activity of lemon (Citrus limon L.) waste extracts against Alternaria alternata and Alternaria citri

ISHS V International Symposium on Postharvest Pathology: From Consumer to Laboratory-Sustainable Approaches to Managing Postharvest Pathogens In vitro antifungal activity of lemon (Citrus limon L.) waste extracts against Alternaria alternata and Alternaria citri

Enrichment of N and bioavailability of P and K of lemon wastes through biotechnological intervention with special reference to Mung bean production

Digested Assam lemon waste was subjected to biomanure production with appropriate concern on carbon emission through biocircular economy concept. For the biomanure production digested waste was treated with different cyanobacterial cultures such as Anabaena variabilis, Aulosira fertilissima, Cylindrospermum muscicola, and Fischerella muscicola. Among all the strains F. muscicola was found to be most efficient in N, P and K enrichment and bioavailability where 2.88, 2.00 and 2.16 folds increase in N, P and K content has been recorded. The produced enriched biomanure was applied solely and in combination with inorganic fertilizer to find out the best treatment condition towards soil enrichment vis a vis mung bean (Vigna radiata) production. Combination of inorganic fertilizer and produced biomanure exhibits good results where the yield of the mung seed was enhanced by 2.02 folds. Application of biomanure in the crop field could maintain the soil physico-chemical properties.

Carbon Quantum Dots from Lemon Waste Enable Communication among Biodevices

A bioinspired method of communication among biodevices based on fluorescent nanoparticles is herein presented. This approach does not use electromagnetic waves but rather the exchange of chemical systems—a method known as molecular communication. The example outlined was based on the fluorescence properties of carbon dots and follows a circular economy approach as the method involves preparation from the juice of lemon waste. The synthesis is herein presented, and the fluorescence properties and diffusion coefficient are evaluated. The application of carbon dots to molecular communication was studied from a theoretical point of view by numerically solving the differential equation that governs the phenomenon. The theoretical results were used to develop a prototype molecular communication platform that enables the communication of simple messages via aqueous fluids to a fluorescence-detecting biodevice receiver.

A Standardized Extract Prepared from Red Orange and Lemon Wastes Blocks High-Fat Diet-Induced Hyperglycemia and Hyperlipidemia in Mice.

Citrus fruits are a rich source of high-value bioactive compounds and their consumption has been associated with beneficial effects on human health. Red (blood) oranges (Citrus sinensis L. Osbeck) are particularly rich in anthocyanins (95% of which are represented by cyanidin-3-glucoside and cyanidin-3-6″-malonyl-glucoside), flavanones (hesperidin, narirutin, and didymin), and hydroxycinnamic acids (caffeic acid, coumaric acid, sinapic, and ferulic acid). Lemon fruit (Citrus limon) is also rich in flavanones (eriocitrin, hesperidin, and diosmin) and other polyphenols. All of these compounds are believed to play a very important role as dietary antioxidants due to their ability to scavenge free radicals. A standardized powder extract, red orange and lemon extract (RLE), was obtained by properly mixing anthocyanins and other polyphenols recovered from red orange processing waste with eriocitrin and other flavanones recovered from lemon peel by a patented extraction process. RLE was used for in vivo assays aimed at testing a potential beneficial effect on glucose and lipid metabolism. In vivo experiments performed on male CD1 mice fed with a high-fat diet showed that an 8-week treatment with RLE was able to induce a significant reduction in glucose, cholesterol and triglycerides levels in the blood, with positive effects on regulation of hyperglycemia and lipid metabolism, thus suggesting a potential use of this new phytoextract for nutraceutical purposes.

Valorization of citrus lemon wastes through biorefinery approach: An industrial symbiosis

The present article deals with the processing of Assam lemon (AL), which is rare and under-explored variety and is abundantly available in North-East India. Studies on valorization of Assam lemon waste (ALW) into various value-added products are limited. During pre-processing of ALW a 4.19 ± 0.11% (v/w) essential oil and 12.67 ± 0.46% (w/w) pectin were recovered. Thereafter, the treated biomass was subjected to partial simultaneous saccharification and co-fermentation (PSSCF) for ethanol production. The maximum ethanol yield was obtained as 12.16 ± 0.15% (v/v) when solid loading, temperature, time and pentose to hexose utilizing strains ratio were kept as 30% (w/v), 35 °C, 24 h and 0.5, respectively. Model was found to be significant having R2 and R2(adj.) of 99.93 and 99.86, respectively. Fermented biomass showed a drastic reduction in crystallinity index (19.49%) along with a major change in FTIR peaks, which corroborates the improved bioconversion process. The overall process efficiency was found to be 69.17%.