Nutshells as Efficient Biosorbents to Remove Cadmium, Lead, and Mercury from Contaminated Solutions
The release of potentially toxic elements into the environment, and their effects on aquatic ecosystems still present a real threat. To avoid such contamination, the use of biological sorbents as an alternative to conventional and expensive water remediation techniques has been proposed. The present study evaluated the potential of 0.5 g L-1 of peanut, hazelnut, pistachio, walnut, and almond shells to remove the requisite concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) from contaminated water. Hazelnut shells were identified as the sorbent with the highest potential and were evaluated in mono- and multi-contaminated mineral water. The influence of sorbent-intrinsic and solution-intrinsic characteristics were assessed. Differences among sorbents were attributed to varying percentages of their main components: cellulose, hemicellulose, and lignin. Matrix complexity increase caused a decrease in Cd removal, presumably due to the diminution in electrostatic interaction, and complexation with anions such as Cl-. When simultaneously present in the solution, contaminants competed, with Pb showing higher affinity to the sorbent than Hg. High efficiencies (>90%) obtained for hazelnut shells for all elements in ultrapure water and for Pb and Hg in mineral water) reveals the high potential of this low-cost and abundant waste for use in the remediation of contaminated waters (circular economy).
Evaluation of pruning wound protection products for the management of almond canker diseases in California
Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Prior to this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, sixteen pruning wound treatments were tested using hand-held spray applications, against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81-100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol, T. atroviride SC1 (recommended 2 g/liter) after pruning.
Future-proof and sustainable healthy diets based on current eating patterns in the Netherlands.
Background: To keep global warming <1.5°C as recommended by the Intergovernmental Panel on Climate Change (IPCC), eating patterns must change. However, future diets should be modeled at a national level and respect cultural acceptability. Objectives: We aimed to identify diets among Dutch adults satisfying nutritional and selected environmental requirements while deviating minimally from the baseline diet among Dutch adults. Methods: We calculated per capita food system greenhouse gas emission (GHGE) targets derived from the IPCC 1.5-degree assessment study. Using individual adult dietary intake from the National Food Consumption Survey in the Netherlands (2007-2010) to form a baseline, we used quadratic optimization to generate diets that followed the baseline Dutch diet as closely as possible, while satisfying nutritional goals and remaining below GHGE targets. We considered 12 scenarios in which we varied GHGE targets [2050: 1.11 kg of carbon dioxide equivalent (kg CO2-eq) per person per day (pppd); 2030: 2.04 kg CO2-eq pppd; less strict 2030: 2.5 kg CO2-eq pppd; no target], modeled eating patterns (food-based dietary guidelines; flexitarian; pescatarian; lacto-ovo-vegetarian; vegan), and conducted exploratory analyses (food diversity; acceptability; food chain interdependency). Results: Optimized solutions for 2030 required major decreases (<33% of baseline values) in consumption of beef, pork, cheese, snacks, and butter and increased consumption (>150% of baseline values) of legumes, fish and shellfish, peanuts, tree nuts, vegetables, soy foods, and soy drink. Eight food groups were within 33%-150% of the baseline diet among Dutch adults. The optimized solution complying to the lowest GHGE target (2050) lacked food diversity, and the (lacto-ovo) vegetarian and vegan optimized diets were prone to nutritional inadequacies. Conclusions: Within Dutch eating habits, satisfying optimization constraints required a shift away from beef, cheese, butter, and snacks toward plant-based foods and fish and shellfish, questioning acceptability. Satisfying 2050 food system GHGE targets will require research in consumer preferences and breakthrough innovations in food production and processing.
Isolation and characterization of micro and nanocrystalline cellulose fibers from the walnut shell, corncob and sugarcane bagasse.
The present study aims to extract and characterize the microcrystalline cellulose (MCC) present in different agro-industrial wastes such as walnut shells, corncob, and sugarcane bagasse. Moreover, it is also the aim of this study to convert MCCs to nanocrystalline cellulose fiber (NCCF), to demonstrate the difference in morphological, structural, thermal, and chemical natures. Corncob cellulose was observed to possess a loosely bounded linear bundle structure. Nanocrystalline cellulose fiber yield from walnut shell and sugarcane bagasse cellulose were higher than corncob cellulose. The thermal stability of cellulose was noted to be high for walnut shell NCCF. Nanocrystalline cellulose fiber of corncob and sugarcane bagasse was estimated to have a low thermal degradation temperature. All the MCCs and NCCFs produced from investigated cellulose sources were found to have type I cellulose. Functional group compositions of cellulose were observed to be intact for converted agro-based NCCF's.
Development of an antioxidant formula based on peanut by‐products and effects on sensory properties and aroma stability of fortified peanut snacks during storage.
Background: An antioxidant formula based on peanut skins and hulls, was developed and characterized for total and single polyphenols, and antioxidant power, considering the contribution provided by each peanut by-product. Then, it was evaluated for its effect on sensory properties and aroma stability of peanut bars over a 100-day period. To this purpose, snacks fortified and not with the natural additive were experimentally produced. Results: Peanut hulls contributed to a greater extent than skins to boost the content of bioactives and the antioxidnt activity of the antioxidant formula, which was marked by a phenol content of (~807 mg GAE g-1 ) and a DPPH activity similar to that of butylated hydroxytoluene (respectively, 85.96% and 89.30%). From a sensory perspective, the incorporation of the formulation in snacks caused only a slightly stronger perception of astringent and bitter notes. Pyrazines, phenol, furan, and pyrrole derivatives outlined the aroma of snacks, being more abundant in fortified than conventional samples. Such volatiles faded over storage with different trends in examined products. For example, the sum of 2,5-dimethylpyrazine, 2-ethylpyrazine and 2,3-dimethylpyrazine was 9.49 and 8.87 ppm at day 15; 5.57 and 7.16 ppm at day 45; 5.03 and 4.65 ppm at day 100, respectively in fortified and conventional snacks; hydroxymethylfurfural decreased constantly over storage in conventional samples, and only after day 45 in fortified bars. Conclusion: Overall, the antioxidant formulation did not compromise the sensory desirability of peanut snacks and induced a preservative effect on their aroma, especially during the first 15 days of storage.
Influence of biomass components, temperature and pressure on the pyrolysis behavior and biochar properties of pine nut shells.
The aim of this work was to compare the yields, proximate composition, structure and surface morphology of biochar derived from lignin, cellulose, hemicellulose and pine nut shell (PNS) at 400-700 ℃. PNS biochars obtained at different pyrolysis pressures in the range of 0.1-2.0 MPa were also studied. The results indicate that the interactions of lignin, cellulose and hemicellulose have smaller effects on the ash content, yield and higher heating value (HHV) of the biochar than they do on the fixed carbon and volatile matter contents. Increasing the pyrolysis temperature improves the HHV of the biochar, and increasing the pyrolysis pressure enhances the biochar yield, surface functional groups and combustion characteristics. The kinetic data for Pb2+ adsorption are best fitted by a pseudo-second-order model, indicating a chemisorption-controlled process. The PNSB550 and PNSB1.0 data are optimally fit by the Freundlich and Langmuir models, respectively. The maximum Pb2+ adsorption capacity is 237.3 mg/g.
Synthesis of novel chemicals from cardanol as a product of cashew nutshell processing.
The conversion of the worldwide chemical production from fossil to sustainable resources is currently one of the most urgent tasks for the chemical industry. Based on this approach cardanol, a mixture of phenols with C15-chains as substituents is produced in some countries of the tropical zone from the processing of cashew nutshells. The paper reports the specific transformation of the aromatic moiety in this cheap material, and thus, the development of a novel route to potential useful green bifunctional chemicals in gram scale. Accordingly, cardanol was converted successfully in three steps into hexane-1,6-diols. The evaluation of appropriate synthesis methods and suitable conditions for each of these reaction steps is presented as an essential topic of these investigations. The target compounds synthesized in the reaction sequence are potential building blocks for future biomass-based chemicals and monomers for green polymeric materials, surfactants, and lubricants.
Novel Antioxidant Packaging Films Based on Poly (ε-Caprolactone) and Almond Skin Extract: Development and Effect on the Oxidative Stability of Fried Almonds.
Antioxidant films based on poly(ε-caprolactone) (PCL) containing almond skin extract (ASE) were developed for food packaging applications. The effect of ASE incorporation on the morphological, structural, colour, mechanical, thermal, barrier and antioxidant properties of the prepared films were evaluated. The structural, tensile and thermal properties of the films were not altered due to ASE addition. Although no significant differences were observed for the oxygen permeability of samples, some increase in water absorption and water vapour permeability was observed for active films due to the hydrophilic character of ASE phenolic compounds, suggesting the suitability of this novel packaging for fatty foods conservation. ASE conferred antioxidant properties to PCL films as determined by the DPPH radical scavenging activity. The efficiency of the developed films was evaluated by the real packaging application of fried almonds at different ASE contents (0, 3, 6 wt.%) up to 56 days at 40 °C. The evolution of peroxide and p-anisidine values, hexanal content, fatty acid profile and characteristic spectroscopy bands showed that active films improved fried almonds stability. The results suggested the potential of PCL/ASE films as sustainable and antioxidant food packaging systems to offer protection against lipid oxidation in foods.
Multiproduct biorefinery based on almond shells: impact of the delignification stage on the manufacture of valuable products.
In this work, an integral valorisation of almond shells through a biorefinery approach was studied. The three main components of almond shells were extracted, isolated and characterised. The autohydrolysis process permitted the extraction of the hemicellulosic fraction obtaining a liquor rich in xylooligosaccharides (22.12 g/L). Then, two different delignification processes, alkaline and organosolv treatments, were proposed to obtain a very high purity lignin (≈90%) which could be further valorised for a wide variety of applications. The valorisation of the high cellulosic content of the delignified solids was carried out using two different methods. On the one hand, producing cellulose nanocrystals and on the other hand obtaining glucose by an enzymatic hydrolysis as well as a spent solid mainly composed by lignin (≈78 wt%). Thus, the proposed biorefinery approach could contribute to a circular economy as all the main components of the almond shells could be revalorised by environmentally friendly procedures.
Anaerobic digestion of waste Tunisian date (Phoenix dactylifera L.): effect of biochemical composition of pulp and seeds from six varieties.
Large amounts of secondary date waste (pulp and seeds) are produced and discarded in Tunisia without proper valorization methods. To study the possibility of valorizing different varieties of Tunisian date waste (pulp and seeds) via anaerobic digestion, batch biochemical methane potential (BMP) tests were carried out under mesophilic temperature. The bio-methane production curves were fitted to the model of modified Gompertz in search of the kinetic parameters. The bio-chemical characterization of the substrates from different varieties (total and volatile solids, COD and contents in carbohydrates, proteins, lipids, polyphenols) was realized. Principal component analysis (PCA) was used to investigate the correlations between the model parameters and biochemical variables. Results show that the biochemical compositions of date pulp and seeds strongly depend on the varieties. The BMP are in the range of 0.295-0.345 and 0.267-0.327 Nm3 CH4·kg COD-1 for pulp and seeds respectively, resulting from the significant biochemical variance among the varieties. The BMP of date seeds was significantly correlated with their VS/TS ratio, carbohydrate and protein contents (p < 0.05). For the pulp, significant correlation was found between BMP, carbohydrate and lipid contents. PCA shows that certain varieties (like pulp and seeds of Deglet Nour and seeds of Bejou) are most suitable for being valorized by anaerobic digestion. The most suitable date varieties for this innovative approach were revealed. This research provided useful knowledge for bioconversion of waste date pulp and seeds to biomass energy.