Addition Of Biopolymers Research Articles

Sustainable and multifunctional polyurethane green composites with renewable materials

Polyurethane materials are characterised by an ever-expanding range of application possibilities due to their versatility. Currently, the management of leftovers as well as post-production and post-consumer waste for the production of biocomposites is one of the most obvious, effective and profitable solutions. Due to the renewable nature of biofillers such as cellulose, lignin, and chitin, their use to obtain composite polyurethane elastomers is a real perspective for the dissemination of more environmentally friendly materials and, at the same time, contributes to additional economic profit. The key aspect for further development of the polyurethane/biopolymer biocomposite concept is to fulfil of a number of currently functioning industry standards, mainly those regarding functional properties. In the presented research, an attempt to obtain advanced polyurethane elastomers with the addition of biopolymers (cellulose, lignin, and chitin) was conducted for the first time. The innovative biocomposites obtained in this way were characterised by good processing parameters (processing times, density) and improved functional properties compared to the standard without the addition of fillers (abrasion resistance, tensile strength, contact angle, hardness). Due to the above-mentioned facts, the described biocomposites can be successfully used for the production of multifunctional elastomeric materials with a wide range of potential applications. Moreover, it is worth noting that the management of waste materials in this way will reduce production costs while indirectly contributing to the protection of the natural environment.Graphical abstract

Experimental investigation of sandy soil stabilization using chitosan biopolymer

The performance of an environmentally friendly biopolymer synthesised from secondary resources to overcome the wind erosion of sandy soil was investigated in this study. The study employed a multi-scale approach to investigate the mechanical, erosional, and hydraulic properties of sandy soil. At the macroscale, experimental techniques such as unconfined and triaxial compression tests, permeability measurements, contact angle assessments, and wind tunnel experiments were utilized to characterize the bulk behavior of the soil. Concurrently, molecular dynamics (MD) simulations were conducted at the nanoscale to predict surface mechanical characteristics and elucidate chemical interactions at the molecular level. Results show that when the outer surface of the sandy particles is coated with a sparse concentration of biopolymer, the sandy aerosol inhibitory performance is significant even under extreme storm conditions reaching speeds of 140 km/h of storms. The study on the impact of biopolymer content, curing time, and curing conditions revealed that the addition of chitosan biopolymer has the ability to enhance the bonding between particles and significantly enhance the mechanical properties of sandy soil. The atomic insight from molecular dynamics reveals huge entanglement between sandy particles and biopolymer by Van der Waals interaction. The results of the Unconfined Compressive Strength test indicate that chitosan enhances the compressive strength of sand by up to 320 kPa. Additionally, the triaxial test demonstrated that the application of chitosan led to a 34.2 kPa improvement in the cohesion of sand. Furthermore, analysis of the permeability test results revealed a decrease in the hydraulic conductivity coefficient from 1.6 × 10^-6 m/s to 5.7 × 10^-7 m/s, representing a reduction of approximately 35 %.

Evaluation of Modified Asphalt Binders with Soybean Oil-Based Polymers: Preparation Temperature and Rheological Characterization

To investigate the feasibility of bio-based polymers in the modification of base asphalt binder, two soybean oil-based polymers (PAESO) were synthesized from bio-monomers with different functionalities via free radical polymerization. The characterization of both PAESOs was conducted using Hydrogen nuclear magnetic resonance and Gel Permeation Chromatography analyses, the results showed that the bio-monomer with a higher functionality exhibited a stronger tendency towards self-polymerization, resulting in the polymer with a high conversion rate (44.44 %) and a slightly lower molecular weight (14.76 kDa). The optimal mixing temperature for preparing PAESO-modified asphalt binders was determined through Molecular Dynamics (MD) simulation and Laser Scanning Confocal Microscopy. The MD simulation results indicated that PAESO-modified asphalt models had reached the most stable configurations at a mixing temperature of 160 °C, as evidenced by fewer and more homogeneous distributed small bright spots observed in fluorescence images. This suggested that the outstanding compatibility between PAESO and asphalt binders could be obtained at the optimal mixing temperature of 160 °C. Furthermore, the rheological characteristics of asphalt binders modified with PAESO were examined through Dynamic Shear Rheometer and Bending Beam Rheometer tests. The results revealed that PAESO mainly exhibited a softening effect by significantly enhancing the flexibility, stress relaxation, fatigue, and thermal cracking resistance of the base asphalt binders at intermediate and low temperatures. PAESO-L modified asphalt manifested elastic properties akin to those observed in polymer-modified asphalt within the low-frequency and high-temperature domain. Additionally, PAESO derived from monomers with a higher functionality presented notable benefits in enhancing thermal and fatigue cracking resistance than that of PAESO with a lower functionality. These findings provide valuable insights for the preparation and development of bio-polymer additives for use in asphalt materials.

Cost-effective seawater desalination by photothermal membranes composed of biopolymers-doped graphene oxide using direct solar steam generation strategy

The current study detailed the impact of the qualitative and quantitative addition of biopolymers, besides the influence of the drying method on the efficacy of the prepared photothermal membranes in seawater desalination using the direct solar steam generation (DSSG) strategy. Three natural polymers (NP) (i.e., cellulose acetate (CA), gum Arabic (GA), and sodium alginate (SA)), one synthetic polymer (i.e., polyvinyl alcohol; PVA) were used in membranes' preparation at different (NP/PVA) weight ratios, while graphene oxide (GO) and silica aerogel (SG) were added as a photothermal absorber and to enhance membrane floatability, respectively. The solar-driven evaporation experiments revealed that the evaporation rates (ER) were enhanced by increasing the NP/PVA ratio. Freeze-dried photothermal membranes demonstrated higher performances (ER = 1.59–3.62 kg/m2/h) compared with the freezing-thawed membranes (ER = 1.36–2.95 kg/m2/h) under 1-sun illumination when the NP/PVA ratio increased from 1:1 to 2:1. Interestingly, among all freeze-dried membranes, SA-based membranes at (SA/PVA = 3:1) ratio reflected the highest performance (ER = 4.33 kg/m2/h) at 1-sun illumination. The recorded high ER can be interpreted by several features: increasing the hydrophilic character of the composite membranes at high NP/PVA ratios, the high microporous structure of the internal channels when applying the freeze-drying method; the high GO content which effectively converts light to thermal energy; adequate membrane thickness (∼0.5 mm); besides the presence of SG to maintain the membrane floatability inducing heat localization. Thus, the study provided low-cost freshwater production at affordable rates using biopolymers-doped graphene oxide for desalination using DSSG systems.

Sustainable Use of Gum Acacia as a Biopolymeric Additive in Ultra‐High Performance Concrete

The main objective of this research is to analyze whether biopolymer (gum acacia) can be used as an admixture for ultra‐high performance concrete (UHPC) and to elucidate the strength, durability, microstructure, and transport properties of biopolymer (gum acacia) incorporated UHPC mixes in combination with the shrinkage reducing agent (SRA). The mechanical, thermal, and durability aspects of UHPC were studied at different ages and curing conditions by adding gum acacia in combination with the SRA. After 28 days under hybrid curing, the compressive strength increased by 22.19% and the flexural strength increased by 41.59% for 1% biopolymer addition. The highest strength and durability were obtained using the hybrid curing procedure using superplasticizer and gum acacia biopolymer at a water‐binder ratio of 0.35. With an improved microstructure, the results revealed improved hydration and durability as revealed through the scanning electron microscopic (SEM) images. The SEM photographs of the concrete showed more polymorphic patterns and crystals overall relative to the UHPC with SRA, while exhibiting little to no microfractures. Through adjustment of the biopolymer proportion and adoption of a suitable curing method, this research presents a new strategy for addressing the negative impact produced by the usage of SRA in UHPC.

Biopolymer as an additive for effective biochar-based rhizobial inoculant

Biochar is an efficient and inexpensive carrier for bacteria that stimulate plant development and growth. In this study, different biopolymer additives (cellulose, xanthan gum, chitin and tryptone) were tested with different addition ratios (1:0.1, 1:0.5 and 1:1) on further enhancing biochar capacity for supporting the growth and activity of Bradyrhizobium japonicum (CB1809). We utilized pine wood biochar (PWBC) pyrolyzed at 400 °C as the base inoculum carrier. The shelf life and survival rate of CB1809 were counted using the colony-forming unit (CFU) method for up to 120 days. Peat served as a standard reference material against which all treatments were compared. Subsequent experiments evaluated the ability of carrier inoculants to promote Glycine max L. (soybean) plant growth and nodulation under different watering regimes, i.e., 55 % water holding capacity (WHC) (D0), 30 % WHC (D1) and, 15 % WHC (D2) using sandy loam soil. Results revealed that among different additives; xanthan gum with 1:0.5 to PWBC [PWBC-xanthan gum(1:0.5)] was observed as a superior formulation in supporting rhizobial shelf life and survival rate of CB1809. In pot experiments, plants with PWBC-xanthan gum(1:0.5) formulation showed significant increase in various physiological characteristics (nitrogenase activity, chlorophyll pigments, membrane stability index, and relative water content), root architecture (root surface area, root average diameter, root volume, root tips, root forks and root crossings), and plant growth attributes (shoot/root dry biomass, shoot/root length, and number of nodules). Additionally, a reduced enrichment of isotopic signatures (δ13C, δ15N) was observed in plants treated with PWBC-xanthan gum(1:0.5), less enrichment of δ15N indicates an inverse link to nodulation and nitrogenase activity, while lower δ13C values indicates effective water use efficiency by plants during drought stress. These results suggest that biopolymers supplementation of the PWBC is useful in promoting shelf life or survival rate of CB1809.

INCREASING THE BEARING CAPACITY OF SOFT WATER-SATURATED CLAY SUBGRADES ROADS

Problem statement. The restoration and development of Ukraine's infrastructure, the elimination of the consequences of the destruction caused by hostilities, and the post-war reconstruction of the country require, first and foremost, the restoration of the road and aerodrome networks in Ukraine, as well as civil and industrial facilities. For the smooth operation of infrastructure facilities located in difficult engineering and geological conditions, it is necessary to increase the bearing capacity of the foundations on which the restoration, reconstruction, construction or overhaul of these facilities is planned. Increasing the bearing capacity of soft, water-saturated clay soils is performed by traditional methods such as the use of geosynthetic materials or lime, as well as new alternative methods such as the addition of biopolymers. The purpose of the article is to analyze foreign experience in the use of effective and environmentally safe materials for consolidating and increasing the bearing capacity of soft water-saturated clay soils and justification of the feasibility of their use in Ukraine based on laboratory studies of soils with the addition of lime and a biopolymer, xanthan gum. Conclusion. An analysis of foreign methods for the use of lime and biopolymers to consolidate and increase the bearing capacity of soft water-saturated clay soils was performed. Studies on the selection of the concentration of lime and biopolymers in the soil mixture were analyzed. Laboratory experimental studies were conducted on soft water-saturated clay soils with varying soil liquidity index and lime content of 2−4 % and xanthan gum content of 2−4 %. The research results showed a significant reduction in deformations of soft soils when they are fixed with biopolymer.

Embodied Energy in the Production of Guar and Xanthan Biopolymers and Their Cross-Linking Effect in Enhancing the Geotechnical Properties of Cohesive Soil

Traditional soil stabilization techniques, such as cement and lime, are known for their menacing effect on the environment through heavy carbon emissions. Sustainable soil stabilization methods are grabbing attention, and the utilization of biopolymers is surely one among them. Recent studies proved the efficiency of biopolymers in enhancing the geotechnical properties to meet the requirements of the construction industry. The suitability of biopolymer application in different soils is still unexplored, and the carbon footprint analysis (CFA) of biopolymers is crucial in promoting the biopolymers as a promising sustainable soil stabilization method. This study attempts to investigate the out-turn of cross-linked biopolymer on soils exhibiting different plasticity characteristics (Medium & High compressibility) and to determine the Embodied carbon factor (ECF) for the selected biopolymers. Guar (G) and Xanthan (X) biopolymers were cross-linked at different proportions to enhance the geotechnical properties of soils. Atterberg’s limits, Compaction characteristics, and Unconfined Compressive Strength were chosen as performance indicators, and their values were analyzed at different combinations of biopolymers before and after cross-linking. The test results have shown that Atterberg’s limits of the soils increased with the addition of biopolymers, and it is attributed to the formation of hydrogels in the soil matrix. Compaction test results reveal that the Optimum Moisture Content (OMC) of biopolymer-modified soil increased, and Maximum Dry Density (MDD) reduced due to the resistance offered by hydrogel against compaction effort. Soils amended with biopolymers and cured for 14, 28, and 60 days have shown an appreciable improvement in Unconfined Compressive Strength (UCS) results. Microlevel analysis was carried out using SEM (Scanning Electron Microscopy) and FTIR (Fourier-transform infrared spectroscopy) to formulate the mechanism responsible for the alteration in targeted performance indicators due to the cross-linking of biopolymers in the soil. The embodied energy in the production of both Guar and Xanthan biopolymers was calculated, and the obtained ECF values were 0.087 and 1.67, respectively.

Synthesis of chitosan based reduced graphene oxide-CeO2 nanocomposites for drug delivery and antibacterial applications

In this study, the unique characteristics of chitosan, reduced graphene oxide (rGO) and cerium oxide (CeO2) based hybrid bionano-composites make a carrier for various drug delivery and antimicrobial applications. The recent literatures shown that addition of biopolymers to rGO and CeO2 based nanocomposites exhibit excellent performance in design and development of biosensors, wound dressings, electrodes, microfluidic chips, drug delivery systems and energy storage applications. Chitosan (CS), reduced graphene oxide (rGO) mixed with cerium oxide (CeO2) to form CS-rGO and CS-rGO-CeO2 hybrid bionano-composites using precipitation method. The physiochemical characterization of casted nanocomposite sheet was done using FTIR, XRD, UV–Vis spectrum, SEM and TGA. The XRD results of CS-rGO-CeO2 revealed that the nanoparticle was found to be crystalline structure. FTIR revealed that nitrogen functionalities of CS interacted with rGO-CeO2 to form hybrid nanocomposites. The thermal gravimetric analysis (TGA) showed that the CS-rGO-CeO2 has better thermal stability up to 550 °C. The SEM confirms the surface morphology of CS-rGO-CeO2 has large surface area with smooth surface. Moreover, the antibacterial properties of nanocomposites exhibit excellent zone of inhibition against Staphylococcus aureus and Escherichia coli. The NIH3T3 cell line evaluations showed superior cell adhesion on hybrid nanocomposites. Hence bionano-composite based on CS, rGO and CeO2 are potential biomaterials for drug delivery and antibacterial applications.

Laterite soil stabilization using cellulose biopolymer

Laterite soil stabilization is a promising technique that aims to enhance the engineering properties of this naturally occurring soil, Cellulose are one of the potential bio-polymer stabilizers that have been widely employed. The effectiveness of Cellulose (CL) biopolymer in stabilizing laterite soil is shown in this study. In various proportions of 0%, 1%, 2%, 3%, and 4% by dry soil mass, cellulose biopolymer is treated with laterite soil. The engineering parameters of soils treated with cellulose biopolymer were determined using modified proctor tests, direct shear tests, and CBR tests. The treated soil's dry density increases slightly up to 3% cellulose content, but the optimum moisture content decreases. The addition of cellulose biopolymer greatly increased the strength and cohesiveness of laterite soil mixtures. The CBR value increases with increasing the cellulose dose up to 3%; however, with addition of dose, the CBR value decreases slightly in both soaked and unsoaked conditions. The examination of the microstructure through field emission scanning electron microscopy (FESEM) examinations revealed the emergence of novel cementitious substances as a consequence of chemical interactions between cellulose and laterite soil components at the microscopic scale. These reactions led to the enhancement of soil composition by fusing soil particles and occupying the voids within the soil framework. The use of cellulose as a material for the stabilization of laterite soil is therefore a solution for an environmentally benign soil stabilizing material.

The Effect of Additional Chitosan and Cellulose on The Performance of Bioplastic from Manihot Glaziovii Starch

Manihot Glaziovii has a starch content of 77.87 making it potential to be used as raw material for bioplastics manufacturing as a substitute for conventional plastics. It requires the addition of biopolymers (fillers) and plasticizers to overcome weaknesses against mechanical properties and water resistance. This study aims to determine the effect of filler variations on the quality of bioplastics to be compared with SNI No.7188.7:2016 using fillers addition in the form of chitosan and cellulose from newsprint and sorbitol as plasticizer were expected to improve the quality of the bioplastics. Melt intercalation method are used with heating temperature of 60°C-80°C for 60 minutes and stirring speed of 500 rpm. The variation of cellulose combination for 30% chitosan (w/w starch) was 10%, 12%, 14%, 16%, and 18% while the variation of chitosan for 16% cellulose (w/w starch) was 20%, 30%, 40 %, 50%, and 60%. Based on the test results, the best characteristic value for the water absorption is 120.65%, biodegradability is 32.74%, tensile strength value is 15.72 MPa, WVTR value is 6.52 g/m2.hour, and elongation is 29.76%. From the test results, it can be concluded that bioplastics made from Manihot Glaziovii starch have not been able to meet SNI No.7188:2016.

Different amount of carboxyl-aldehyde fractionated nanofibril cellulose and main characteristics of chitosan, gelatin, alginate added composites

In this research, two different types of nanofibrillated celluloses (NFCs) having different amounts of aldehyde and carboxyl groups were mixed with chitosan (CH), gelatin (GL), and alginate (AL) with different mixing ratios to produce biocomposite aerogels. There was no related study in the literature about producing aerogels with the addition of NC and mentioning biopolymers in addition to the effect of carboxyl and aldehyde fraction of the main matrix NC on composite properties. For this purpose, the main aim of this study was to investigate how carboxyl and aldehyde groups affect the basic characteristics of NFC-biopolymer based materials addition to efficiency of biopolymer amount in main matrix. Even after preparing homogenous NC-biopolymer compositions at 1 % concentration with varied proportions (75 %–25 %, 50 %–50 %, 25 %–75 %, 100 %), aerogels were still made using the fundamentally easy lyophilization procedure. Porosity values for NC-Chitosan (NC/CH) based aerogels range from 97.85 to 99.84 %, whereas those made from NC-Gelatin (NC/GL) and NC-Alginate (NC-AL) have values of 99.2–99.8 % and 98.47 to 99.7 %, respectively. In addition, densities were determined in the range of 0.01 g/cm3 for both NC-CH and NC-GL composites, but higher values were obtained in ranged between 0.01 and 0.03 g/cm3 for NC-AL samples. The crystallinity index values showed a decreasing trend with the addition of biopolymers into NC composition. SEM images showed that all materials have a porous micro structure with different size pores and homogenous surface topography. As a result of the specified tests, these materials can be used in many different industrial applications, such as dust collectors, liquid adsorbers, specific material for packaging and medical materials.

Adsorption of Copper and Arsenic from Water Using a Semi-Interpenetrating Polymer Network Based on Alginate and Chitosan.

New biobased hydrogels were prepared via a semi-interpenetrating polymer network (semi-IPN) using polyacrylamide/chitosan (PAAM/chitosan) hydrogel for the adsorption of As(V) or poly acrylic acid/alginate (PAA/alginate) hydrogel for the adsorption of Cu(II). Both systems were crosslinked using N,N'-methylenebisacrylamide as the crosslinker and ammonium persulfate as the initiating agent. The hydrogels were characterized by SEM, Z-potential, and FTIR. Their performance was studied under different variables, such as the biopolymer effect, adsorbent dose, pH, contact time, and concentration of metal ions. The characterization of hydrogels revealed the morphology of the material, with and without biopolymers. In both cases, the added biopolymer provided porosity and cavities' formation, which improved the removal capacity. The Z-potential informed the surface charge of hydrogels, and the addition of biopolymers modified it, which explains the further metal removal ability. The FTIR spectra showed the functional groups of the hydrogels, confirming its chemical structure. In addition, the adsorption results showed that PAAM/chitosan can efficiently remove arsenic, reaching a capacity of 17.8 mg/g at pH 5.0, and it can also be regenerated by HNO3 for six cycles. On the other hand, copper-ion absorption was studied on PAA/alginate, which can remove with an adsorption capacity of 63.59 mg/g at pH 4.0, and the results indicate that it can also be regenerated by HNO3 for five cycles.

Microencapsulates of Blue Maize Polyphenolics as a Promising Ingredient in the Food and Pharmaceutical Industry: Characterization, Antioxidant Properties, and In Vitro-Simulated Digestion.

An anthocyanin-rich blue maize waste product was used for anthocyanin extraction. To preserve bioactive phenolic compounds, a spray-drying technique was employed using conventional wall material maltodextrin (MD), with novel one, hydroxypropyl-β-cyclodextrin (HPBCD). The obtained spray-dried maize extract (SME) and microencapsulates were analyzed based on physicochemical powder properties, chemical analysis, antioxidant activity, and digestibility. The examined microencapsulates demonstrated good powder properties, exhibited a high powder yield (up to 83%), and had a low moisture content (less than 5%). HPBCD and MD + HPBCD combinations demonstrated superior powder properties in the terms of decreasing the time necessary for rehydration (133.25 and 153.8 s, respectively). The mean average particle diameter ranged from 4.72 to 21.33 µm. DSC analyses signified high powder thermal stability, around 200 °C, related to the increasing preservation with biopolymer addition. The total phenolic and anthocyanin compounds ranged from 30,622 to 32,211 mg CE/kg (CE-catechin equivalents) and from 9642 to 12,182 mg CGE/kg (CGE-cyanidin 3-glucoside equivalents), respectively, associated with good bioactive compound protection. Microencapsulates with both carriers (15% MD and 15% HPBCD) had the highest digestibility (73.63%). Our results indicated that the microencapsulates created with the active ingredient and the wall materials (MD and HPBCD) could protect phenolic compounds/anthocyanins against ABTS radicals (63.53 and 62.47 mmol Trolox Eq/kg, respectively).

Effect of Varying Curing Conditions on the Strength of Biopolymer Modified Sand.

Recently, the improvement of the engineering properties of soil has been centered on using sustainable and eco-friendly materials. This study investigates the efficacy of three biopolymers: Acacia, sodium alginate, and pectin, on the unconfined compressive strength (UCS) of dune sand. The UCS test measured the effects of the biopolymer type and concentration, curing intervals and temperature, and moisture loss. The changes in the morphology caused by the biopolymer addition were examined via scanning electron microscopy (SEM). Results indicate that the UCS of the biopolymer-modified sand increased with biopolymer concentration and curing intervals. Varying the curing temperature from 25-110 °C, slightly affected the strength of the acacia-modified sand specimen, increased that of the sodium alginate-modified sand specimen up to a temperature of 85 °C, and continued to decrease that of the pectin-modified sand specimen as the temperature was increased from 25 to 110 °C. The SEM images indicated that the biopolymer's presence within the sand pores significantly contributed to the strength. Bond decomposition occurs at temperatures greater than 110 °C for sodium alginate and pectin-modified sands, whereas bonds remain stable at higher temperatures for the acacia-modified sand. In conclusion, all three biopolymers show potential as robust and economic dune stabilisers.

In Vitro Bioaccessibility of Bioactive Compounds of Freeze-Dried Orange Juice Co-Product Formulated with Gum Arabic and Modified Starch

The large amount of waste generated by the orange juice industry has sparked the interest of many researchers in incorporating recycling systems and following a much more sustainable circular economy model. This work proposes the valorization of the co-product generated in the orange juice extraction industry after freeze-drying for its subsequent reuse as a natural ingredient in the food industry. In addition, the possible protective effect of gum Arabic and corn starch esterified with octenyl succinic groups, in proportions optimised in previous studies 0.25 and 0.45 g/g orange co-product dry solutes, on the main bioactive compounds of orange peel during the freeze-drying process has been studied. The samples were characterised for their content of vitamin C (ascorbic and dehydroascorbic acids), flavonoids (hesperidin and narirutin), total phenols and total carotenoids, as well as their antioxidant capacity (DPPH and FRAP assays). In addition, samples were digested, mimicking the human enzymatic oral gastro-intestinal digestion process, and the bioaccessibility of the bioactive compounds was evaluated. It was observed that the addition of both biopolymers improved the stability of the hydrophilic compounds during freeze-drying. This conservative effect was more remarkable for higher biopolymer concentrations. However, no protective effect on carotenoid compounds was observed. This trend was reflected in the antioxidant activity of the different samples. In addition, the incorporation of biopolymers improved the bioaccessibility of the bioactive compounds studied. In conclusion, the results supported the feasibility of the freeze-dried orange juice co-product as a natural, sustainable source of health-promoting compounds.

Effect of addition of biopolymer coated DAP on phosphorus release kinetics over an incubation time

Phosphorus (P) use efficiency is very low (5 to 25%) due to fixation with Ca+2/Mg+2 in alkaline/calcareous soils and Fe2+/Al3+ in acid soils, reduces the availability of phosphorus in soil. Among the various approaches used to enhance PUE, polymer coated fertilizers are relatively a new concept. Therefore, to alleviate the effects of low use efficiency of inorganic fertilizers and its losses in soil, the incubation study was conducted during 2020 at Tamil Nadu Agricultural University to check the slow-release behaviour of coated DAP fertilizer using biopolymers like chitosan and sodium alginate. The incubation experiment was made with six different coatings of biopolymers and uncoated DAP for studying the release behaviour of P from coated fertilizers. Randomized block design was followed with seven treatments in triplicate and sampling was taken at the intervals of 2nd hour, 4th hour, 120th hour, 7, 14, 28, 35, 42 and 49 days of incubation. A study on slow-release property of coated fertilizers indicated that the treatment combination of both chitosan and sodium alginate (C5A5 - CSACDAP) coated DAP performed well by releasing the P from coated fertilizer was achieved till 35th day of incubation followed by the combination of both chitosan and sodium alginate (C4A4 - CSACDAP). This study indicated that the combination of both the polymers forms a strong polyion complex and tends to give the P release for a longer period than the individual coatings of both polymers on the DAP granule.

Sustainable biopolymer soil stabilisation: the effect of microscale chemical characteristics on macroscale mechanical properties

Sustainable biopolymer additives offer a promising soil stabilisation methodology, with a strong potential to be tuned to soil’s specific nature, allowing the tailoring of mechanical properties for a range of geotechnical applications. However, the biopolymer chemical characteristics driving soil mechanical property modifications have yet to be fully established. Within this study we employ a cross-scale approach, utilising the differing galactose:mannose (G:M) ratios of various Galactomannan biopolymers (Guar Gum G:M 1:2, Locust Bean Gum G:M 1:4, Cassia Gum G:M 1:5) to investigate the effect of microscale chemical functionality upon macroscale soil mechanical properties. Molecular weight effects are also investigated, utilising Carboxy Methyl Cellulose (CMC). Soil systems comprising of SiO2 (100%) (SiO2) and a Mine Tailing (MT) exemplar composed of SiO2 (90%) + Fe2O3 (10%) (SiO2 + Fe) are investigated. The critical importance of biopolymer additive chemical functionality for the resultant soil mechanical properties, is demonstrated..For Galactomannan G:M 1:5 stabilised soils the ‘high-affinity, high-strength’, mannose-Fe interactions at the microscale (confirmed by mineral binding characterisation) are attributed to the 297% increase in the SiO2 + Fe systems Unconfined Compressive Strength (UCS), relative to SiO2 only. Conversely for SiO2 Galactomannan-stabilised soils, when increasing the G:M ratio from 1:2 to 1:5, a 85% reduction in UCS is observed, attributed to mannose’s inability to interact with SiO2. UCS variations of up to a factor of 12 were observed across the biopolymer–soil mixes studied, in line with theoretically and experimentally expected values, due to the differences in the G:M ratios. The limited impact of molecular weight upon soil strength properties is also shown in CMC-stabilised soils. When considering a soil’s stiffness and energy absorbance, the importance of biopolymer–biopolymer interaction strength and quantity is discussed, further deciphering biopolymer characteristics driving soil property modifications. This study highlights the importance of biopolymer chemistry for biopolymer stabilisation studies, illustrating the use of simple low-cost, accessible chemistry-based instrumental tools and outlining key design principles for the tailoring of biopolymer–soil composites for specific geotechnical applications.Graphical abstract

Antimicrobial Efficiency of Chitosan and Its Methylated Derivative against Lentilactobacillus parabuchneri Biofilms.

Antimicrobial materials are considered potential alternatives to prevent the development of biofilm-associated contaminations. Concerns regarding synthetic preservatives necessitate the development of innovative and safe natural antimicrobials. In the present study, we discuss the in situ infrared attenuated total reflection spectroscopy (IR-ATR) investigations of the selective antimicrobial efficiency of chitosan in controlling the growth of Lentilactobacillus parabuchneri biofilms. The protonated charges of chitosan were additionally amplified by structural modification via methylation, yielding quaternized derivative TMC (i.e., N, N, N-trimethyl chitosan). To evaluate antimicrobial effectiveness against L. parab. biofilms, IR-ATR spectroscopy provided information on molecular mechanisms and insights into chemical changes during real-time biofilm inhibition studies. The integrated fiberoptic oxygen microsensors enabled monitoring oxygen (O2) concentration gradients within biofilms, thereby confirming the metabolic oxygen depletion dropping from 4.5 to 0.7 mg L-1. IR studies revealed strong electrostatic interactions between chitosan/its water-soluble derivative and bacteria, indicating that a few hours were sufficient to affect biofilm disruption. The significant decrease in the IR bands is related to the characteristic spectral information of amide I, II, III, nucleic acid, and extracellular polymeric matrix (EPS) produced by L. parabuchneri biofilms. Cell clusters of biofilms, microcolonies, and destabilization of the EPS matrix after the addition of biopolymers were visualized using optical microscopy. In addition, scanning electron microscopy (SEM) of biofilms grown on polystyrene and stainless-steel surfaces was used to examine morphological changes, indicating the disintegration of the biofilm matrix into individual cells. Quantification of the total biofilm formation correlated with the CV assay results, indicating cell death and lysis. The electrostatic interactions between chitosan and the bacterial cell wall typically occur between protonated amino groups and negatively charged phospholipids, which promote permeabilization. Biofilm growth inhibition was assessed by a viability assay for a period of 72 h and in the range of low MIC values (varying 0.01-2%). These results support the potential of chitosan and TMC for bacterial growth prevention of the foodborne contaminant L. parabuchneri in the dairy industry and for further implementation in food packaging.

Pectin/microwax composites for surface coating and protection

A novel coating for surface protection of artwork was investigated by the development of biofilms based on pectin matrix filled with halloysite/wax microspheres. Firstly, we prepared Pickering emulsion (PE) of wax/halloysite by following the protocol reported in our previous works. Then, Pectin (PEC) was added to the Pickering emulsions. The dispersion was observed by digital microscope, which evidenced that the sizes of the wax droplets is affected by the biopolymer addition. The physico-chemical properties of the film, which was obtained by the solvent casting method, were investigated by water Contact Angle experiments, UV–vis Spectroscopy and Dynamic mechanical analysis (DMA). Transparency analysis and the effects of the halloysite/wax microspheres on the hydrophobic/hydrophilicity character of the biofilm proved that the nanocomposite system represents a promising coating for surface protection. Pure pectin and pectin/microwax films were investigated by DMA analysis to determine their tensile properties. The proposed coating is environmentally friendly and a good strategy for the protection of stone artwork’s surfaces.