Renewable Waste Material Research Articles

Green and facile fabrication of multifunctional cellulose nanocrystal and carvacrol together reinforced chitosan bio-nanocomposite coatings for fruit preservation

The continuous development of sustainable food-active packaging materials and practices with high performance is a response to the increasing challenges posed by microbial food safety and environmental contamination. In this study, a multifunctional bio-nanocomposite composed primarily of chitosan, cellulose nanomaterials and carvacrol was proposed as a conformal coating for fruit preservation. The coating exhibits excellent antioxidant and antibacterial activities owing to the incorporation of the carvacrol. The inhibition rate of the coating on E. coli and S. aureus is enhanced by 57.13 % and 62.18 %, respectively. And its antioxidant activities is also improved by 77.45 %. In addition, the oxygen permeability (OP) and water vapor permeability (WVP) of this CS/CNC coating are significantly lowered by 67 % and 46 %, respectively, comparing with the CS coating. The coating exhibited excellent biosafety and cytocompatibility because of over 90 % of the HepG2 cells remained alive in each concentration of the coating after 24 h incubation. Additionally, the efficacy of the coating in prolonging the freshness and visual appeal of perishable fruits is substantiated by the experiment involving two fruit specimens. Furthermore, the coating's ease of production, ingestibility, washability, and utilization of cost-effective and easily accessible biomaterials, including renewable waste materials, indicate its potential as a viable economic substitute for commercially accessible fruit coatings.

Renewable benzoxazine-based thermosets from cashew nut: Investigating the self-healing, shape memory, recyclability and antibacterial activity

The preparation of sustainable bio-based polybenzoxazines with multifuctional applications is highly desirable but still challenging. Here, we propose a facile strategy to address this dilemma by introducing dioxaborolane bonds into the benzoxazine network. Renewable dynamic cardanol-based polybenzoxazine networks were prepared using the renewable waste material, cardanol (a byproduct of cashew nut processing), as the starting material and fabricated by incorporating dioxaborolane bonds. The dioxaborolane-containing cardanol-based benzoxazine thermosets (PCBOz-DBs) showed excellent reprocessability, self-healing property, shape memory behavior, and antibacterial activity. PCBOz-DBs have a controllable mechanical strength in a wide range between stretchability (elongation at break: over 587%) and stiffness (tensile strength: 5.88 MPa), as well as an excellent shape memory performance, by tailoring dioxaborolane bond content without catalyst. The polymer has a strong tissue-adhesive property and can firmly adhere to a variety of substrates, such as metal, plastic, and glass. PCBOz-DBs showed inhibition rates of 95.61% and 99.98% against Escherichia coli and Staphylococcus aureus, respectively. Moreover, the distinct network makes PCBOz-DB recyclable over multiple times without compromising its property, showing significant and self-healing properties under relatively low temperature (100 °C) and short healing time (5 min). The prepared PCBOz-DB, which is reusable, recyclable, and renewable, can achieve the goal of cleaner production by using bio-renewable biomass and reducing petrochemical resources, production, and energy emissions.

Liquid fertilizer production from organic waste by conventional and microwave-assisted extraction technologies: Techno-economic and environmental assessment

The use of mineral fertilizers in agriculture has significantly increased to support the growing global food demand. Organic fertilizers are produced from renewable waste materials to overcome the drawbacks of inorganic fertilizers. The development of novel production processes of organic fertilizers entails a significant advance towards the circular economy that reincorporates waste materials into the production cycle. In this work, the economic and environmental feasibility of an industrial plant with a treatment capacity of 300 kg/h of organic waste for the production of liquid fertilizers has been performed. Two extraction technologies (conventional and microwave) and two solvents (water and alkaline) have been compared to select the most sustainable and profitable scenario for scaling-up. The extraction process consists of 2 steps: extraction followed by a concentration stage (necessary only if water extraction is applied). The resolution of the mass balances shows that the fertilizer production under alkaline conditions is ten times higher than for water-based extraction. The economic analysis demonstrated that the total investment cost of microwave technology (>3.5 M€) is three times higher compared to the conventional extraction technology (<1.5 M€), mainly due to the higher complexity of the equipment. These facts directly impact the minimum selling price, because the fertilizers obtained by conventional extraction with alkaline solvent would have a lower selling price (about 1 €/L). As for environmental assessment, the indicators show that the environmental impact produced by water-based extraction is higher than alkaline-solvent extraction, mainly due to the necessity of a concentration stage of the liquid extract to meet the requirements of European regulations. In view of the results obtained in the economic and environmental evaluation, it could be concluded that the most favourable scenario for scaling up the production of liquid fertilizers from organic waste is the conventional extraction under alkaline conditions.

Circular economy based landfill leachate treatment with sulphur-doped microporous biochar

There is now increasing interest in the creation of a more ‘circular economy’, with a particular aim to eliminate waste – by design, within which products are optimised to be reused, restored or returned. Here, a sulphur functionalised microporous biochar was synthesised from an abundant biomass waste material (cherry kernels), for the selective removal of Pb(II) from landfill leachate as a representative heavy metal. The production process utilises renewable waste material and removes toxic chemicals. Characterisation of the biochar showed that pyrolysis and functionalisation formed an adsorbent with a microporous structure and rich surface chemical functionality. The adsorption process was optimised using a ‘response surface methodology – Box-Behnken Design’. Lead removal efficiency approached 99.9% under optimised experimental conditions, i.e., where the solution pH was 6.0, the biochar dose was 4.0 g/L and the contact time was 47 min. The adsorption process was best described using a Freundlich model. The maximum amount of Pb(II) adsorbed was 44.92 mg/g. The main adsorption mechanisms occurred through outer-sphere (electrostatic attraction) and inner-sphere complexation. Desorption studies showed that three successful regeneration cycles (with acidic deionised water) could be used post pyrolysis. The biochar removed 97% of Pb(II) from landfill leachate samples, as compared to 9.4%, and 7.6% for two commercial activated carbon adsorbents. These findings demonstrate the high selectivity of this biochar towards Pb(II) and its applicability even in the presence of high concentrations of many potentially interfering inorganic and organic ions and compounds.

The potential of the oleaginous yeast Rhodotorula paludigena CM33 to produce biolipids

Sixty-seven yeast strains were isolated from castor beans then their endogenous lipids were stained by Nile Red (NR) fluorescence dye, and flow cytometry was used to obtain a strain with a high relative mean fluorescence intensity (MFI) value. The highest MFI value was obtained for strain CM33, which produced a maximum lipid content of 20.8 % dry cell weight (DCW). Based on the sequence of the ITS-5.8S-ITS rDNA and D1/D2 26S rDNA regions, CM33 showed 99 % identity with Rhodotorula paludigena. The potential of CM33 to assimilate various carbon sources was examined by growth on minimal media using glucose, glycerol, sucrose or xylose. CM33 was grown in glucose-based medium for 96 h and exhibited a maximum lipid content of 23.9 % DCW. Furthermore, when cells were cultured on molasses waste, their biomass, lipid content and lipid concentration reached 16.5 g/L, 37.1 % DCW and 6.1 g/L, respectively. These results demonstrated the potential of R. paludigena CM33 to contribute to a value-added carbon chain by converting renewable waste materials for biolipid production.

Production of Plant-Derived Oleuropein Aglycone by a Combined Membrane Process and Evaluation of Its Breast Anticancer Properties.

Natural products and herbal therapies represent a thriving field of research, but methods for the production of plant-derived compounds with a significative biological activity by synthetic methods are required. Conventional commercial production by chemical synthesis or solvent extraction is not yet sustainable and economical because toxic solvents are used, the process involves many steps, and there is generally a low amount of the product produced, which is often mixed with other or similar by-products. For this reason, alternative, sustainable, greener, and more efficient processes are required. Membrane processes are recognized worldwide as green technologies since they promote waste minimization, material diversity, efficient separation, energy saving, process intensification, and integration. This article describes the production, characterization, and utilization of bioactive compounds derived from renewable waste material (olive leaves) as drug candidates in breast cancer (BC) treatment. In particular, an integrated membrane process [composed by a membrane bioreactor (MBR) and a membrane emulsification (ME) system] was developed to produce a purified non-commercially available phytotherapic compound: the oleuropein aglycone (OLA). This method achieves a 93% conversion of the substrate (oleuropein) and enables the extraction of the compound of interest with 90% efficiency in sustainable conditions. The bioderived compound exercised pro-apoptotic and antiproliferative activities against MDA-MB-231 and Tamoxifen-resistant MCF-7 (MCF-7/TR) cells, suggesting it as a potential agent for the treatment of breast cancer including hormonal resistance therapies.

Transfer hydrogenation of levulinic acid from glycerol and ethanol using water-soluble iridium N-heterocyclic carbene complexes

The upgrading of biomass derivatives to biofuels and chemicals through transfer hydrogenation (TH) is attractive relative to direct hydrogenation, especially when the hydrogen donors can be sourced renewably. Here we report the first process that uses glycerol, a renewable waste material from biodiesel processing, as a hydrogen donor in the catalytic TH of a biomass-derived platform chemical, levulinic acid, to selectively afford γ-hydroxyvaleric acid (GHV) and lactic acid (LA). GHV can be further converted to γ-valerolactone (GVL), a widely used platform chemical. Levulinic acid can be used directly, without esterification, which is typically needed for transfer hydrogenation. The process is efficiently facilitated by robust iridium N-heterocyclic carbene (NHC) complexes with sulfonate functional groups at low catalyst loading (1–10 ppm), affording quantitative conversion of levulinic acid in the presence of KOH to GHV, with >100,000 TON in 2 h at 150 °C, using 1 ppm catalyst. The most prolific catalyst, [(NHC-SO3-)2(CO)2Ir]Na, can also facilitate transfer hydrogenation from other hydrogen donors, such as 2-propanol, potassium formate, and most notably, ethanol, which can also be derived from renewables. Ethanol is a highly efficient hydrogen donor for levulinic acid using this catalyst, affording >7,000 turnovers in 2 h using 10 ppm catalyst.

Upcycling waste seashells with cement: Rheology and early-age properties of Portland cement paste

To reduce solid waste discharges into environment and virgin resource consumptions in construction, waste seashells from seafood and aquaculture industry were recycled into powder form and reused in cementitious construction materials. This work aimed to use this biologically renewable waste material as a possible alternative to the nonrenewable limestone mineral used conventionally with Portland cement. The study explored roles of seashell powder as both a partial replacement and an additional additive to cement through evaluating the rheological and physico-mechanical properties of early-age cement paste. The cyclic rheological measurement including model analysis (Bingham, Casson, and Herschel-Bulkley models) was conducted to reveal the time- and shear-dependent workability of fresh cement paste during the first 2 h. Connecting to rheology, physico-mechanical measurements were carried out to understand hydration mechanisms of cement paste with seashell powder. Seashell powder was found to improve the rheological and early hydration behaviors of Portland cement paste. A parallel comparison between limestone and seashell powders was conducted to understand different roles of the two calcium carbonate minerals in cement system. Results from this study indicated the unique physical features and chemical reactivities of seashell powder in cement system, and thus suggested a promising feasibility to recycle waste seashells with cementitious construction materials.

Lithium silicate based catalysts prepared using arecanut husk ash for biodiesel production from used cooking oil

The proficient and cost-effective utilization of renewable waste materials for the solid catalyst development facilitates the commercial production of biodiesel through a green route. Here, arecanut husk ash, chemically modified with lithium compound is used as an efficient solid catalyst for the biodiesel production from used cooking oil. Lithium silicates are the major crystalline materials present in the lithium impregnated heterogeneous base catalyst. The activity of the arecanut husk ash derived catalyst in the transesterification of used cooking oil is excellent with a low catalyst loading under mild reaction conditions. Catalyst is best suited in the production of biodiesel from low cost feed stocks having high free fatty acid content and is found to be reusable.

Soil-plant nitrogen pools in nectarine orchard in response to long-term compost application

The search for sustainable source of N, the need of soil organic matter restoration, along with the call for recycling of organic wastes has led to a rise of the use of organic fertilizers. The aim of the present experiment was to evaluate: the effectiveness of compost application as a N fertilizer, the impact on N distribution in soil and plant and on tree performances, in a long-term experiment (14 years).The study was carried out in the Po valley, Italy and, since orchard planting (2001), the following treatments were applied: 1. unfertilized control; 2. mineral fertilization; 3. compost at a rate of 5 t DW ha−1 yr−1; 4. compost at a rate of 10 t DW ha−1 yr−1. Soil total N, potentially mineralizable, microbial and extractable N were higher in compost in comparison to mineral (fertilizer). The effect was found both in the row and in the inter-row and the rise of N fractions was evident in the shallowest soil layer of the row. Soil mineral, potentially mineralizable N was increased by mineral (11.1 mg kg−1) and compost 10 (12.4 mg kg−1) fertilization compared with control (6.7 mg kg−1). Vegetative growth and yield were increased in trees treated with mineral and compost 10; moreover, these plants were able to recycle (66.1 and 70.5 kg ha−1 yr−1, respectively) and remobilize (41.5 and 48.7 kg ha−1 yr−1, respectively) a higher amount of N than those of control and compost 5. In conclusion, organic fertilization strategy promoted the buildup of soil N reserve, meaning a capacity of the ecosystem to sequestrate N. The application of compost 10 showed a similar effect on plant growth and production as mineral fertilization, but introduced the advantage of the use of a cheap, renewable waste material, providing a new insight on N fertilization management.

Visible light-mediated and water-assisted selective hydrodeoxygenation of lignin-derived guaiacol to cyclohexanol

Hydrodeoxygenation of lignin-derived guaiacol is achieved by magnetically separable bimetallic AgPd supported on carbon nitride using formic acid as H2 source; nitride support is obtainable via calcination of chitosan, a marine-derived renewable waste material.

Clean synthesis of epoxy plasticizer with quaternary ammonium phosphotungstate as catalyst from a byproduct of cashew nut processing

The toxic petroleum-based phthalates account 80% of the total plasticizer consumption in China. Conventional methods for preparing epoxy plasticizers produces a large amount of waste water. Furthermore, cardanol (a byproduct of cashew nut processing) has the potential to be an economic alternative for producing fine chemical products. Here we reported a strategy for acid-free catalytic production of epoxy plasticizer using renewable waste material cardanol as starting material and quaternary ammonium phosphotungstate as catalyst. The optimum epoxidation reaction parameters were investigated and the epoxy value of epoxidized cardanol based plasticizer was 5.2% at optimal reaction conditions. Remarkably, the catalyst was recycled and the percent recovery in the first recycle was 89.0%. Performances of plasticized PVC films showed that epoxidized cardanol based plasticizer improved thermal stability and decreased the glass transition temperature of PVC. Plasticizing efficiency of epoxidized cardanol based plasticizer reached 82.2%. Epoxidized cardanol based plasticizer is biologically safe without acute toxicity and showed more excellent solvent resistance and lower volatilization than dioctyl phthalate. In conclusion, a cleaner environment-friendly plasticizer derived from a waste material was produced by acid-free catalysis. The strategy introduced renewable waste material cardanol into the environment-friendly plasticizer production to substitute dioctyl phthalate and had potential application value to reduce pollution and improve human health.

Utilization of renewable waste material for the sustainable development of thermally stable and biologically active aliphatic amine modified Cardanol (phenolic lipid) - Formaldehyde free standing films

Abstract The recognition of the alarming increased cost and looming exhaustion of petroleum resources for the production of polymeric resins for versatile applications has prompted us to switch towards green and sustainable resources. There is an immediate urge to develop bio-based polymeric resins via sustainable routes with enhanced properties for their utilization in polymer and coating applications. The present investigation reports the synthesis and characterization of aliphatic amine, Hexamethylene tetramine (HMTA) modified Cardanol(Col)-Formaldehyde(F) (Col-FA) free standing films and coatings for versatile applications through the use of cost-effective and renewable starting material, Col (agro byproduct of cashew nut processing) and HMTA (optimum amount, 15%) obviating the toxic solvent usage. The result indicated transparent (red-yellow colored), homogenous Col-FA films with amorphous morphology, and can serve as an eco-friendly, thermally stable (up to 430–440 °C), chemically resistant (against various solvents), mechanically robust and biologically active (moderate activity) material. The overall synthesis strategy is environmentally benign, employs safer chemistry and is consistent with the principles of “Green Chemistry” (principles 1, 2, 3, 4, 5, 6, 7, 8, and 12). This is a highly desirable and excellent approach to develop free standing, transparent, flexible, thermally stable, chemically resistant and antibacterial thin films/coatings to increase the application of Col.

A renewable waste material for the synthesis of a novel non-halogenated flame retardant polymer

The recognition of toxicity and environmental persistence of halogenated flame retardant (FR) materials has prompted the reduction in their usage across the globe. There is an immediate need for new types of non-toxic and effective FR produced preferably through sustainable routes. Here we report the synthesis and characterization of a new polyphenolic FR material based on a renewable and biodegradable starting material, cardanol (a byproduct of cashew nut processing). Cardanol was polymerized in aqueous media using various types of oxidants. The thermal properties of the resulting polymers were investigated. Polycardanol synthesized using a specific type of oxidant exhibited good thermal stability and low heat release capacity. Preliminary results obtained from this study are quite promising and indicate the possibility of synthesizing new types of FR materials from bio-based phenols.

Strategies for PHA production by mixed cultures and renewable waste materials

Production of polyhydroxyalkanoates (PHA) by mixed cultures has been widely studied in the last decade. Storage of PHA by mixed microbial cultures occurs under transient conditions of carbon or oxygen availability, known respectively as aerobic dynamic feeding and anaerobic/aerobic process. In these processes, PHA-accumulating organisms, which are quite diverse in terms of phenotype, are selected by the dynamic operating conditions imposed to the reactor. The stability of these processes during long-time operation and the similarity of the polymer physical/chemical properties to the one produced by pure cultures were demonstrated. This process could be implemented at industrial scale, providing that some technological aspects are solved. This review summarizes the relevant research carried out with mixed cultures for PHA production, with main focus on the use of wastes or industrial surplus as feedstocks. Basic concepts, regarding the metabolism and microbiology, and technological approaches, with emphasis on the kind of feedstock and reactor operating conditions for culture selection and PHA accumulation, are described. Challenges for the process optimization are also discussed.

Lignin reinforced rubber composites

AbstractLignin, a renewable waste material of pulp and paper industries, was analyzed through Fourier‐Transform Infrared Spectroscopy (FTIR) and found to be structurally similar to kraft lignin. Surface modification by addition of benzoyl peroxide and subsequent heating at 70°C caused generation of new functional groups in lignin. Efficacy of the crude lignin as well as that of the modified variety as a filler in nitrile rubber (NBR) has been evaluated. Rubber vulcanizates were analyzed for physico‐mechanical properties, oil and fuel resistance, and thermal stability, and compared with conventional fillers like phenolic resin and carbon black. Modified lignin has been found to produce superior elongation, hardness and compression set properties compared to phenolic resin but inferior to carbon black. Resistance to swelling, however, depends on the type of oil or fuel, and modified lignin always showed better properties than carbon black. Both thermo‐gravimetric analysis (TGA) and thermo‐mechanical analysis (TMA) showed highest thermal stability for the modified lignin followed by phenolic resin and carbon black.