Upcycling agro-industrial blueberry waste into platform chemicals and structured materials for application in marine environments

Blueberry pruning waste (BPw), sourced as residues from agroforestry operations in Chile, was used to produce added-value products, including platform chemicals and materials. BPw fractionation was implemented using biobased solvents (γ-valerolactone, GVL) and pyrolysis (500 °C), yielding solid fractions that are rich in phenols and antioxidants. The liquid fraction was found to be enriched in sugars, acids, and amides. Alongside, filaments and 3D-printed meshes were produced via wet spinning and Direct-Ink-Writing (DIW), respectively. For the latter purpose, BPw was dissolved in an ionic liquid, 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), and regenerated into lignocellulose filaments with highly aligned nanofibrils (wide-angle X-ray scattering) that simultaneously showed extensibility (wet strain as high as 39%). BPw-derived lignocellulose filaments showed a tenacity (up to 2.3 cN dtex−1) that is comparable to that of rayon fibers and showed low light reflectance (RES factor <3%). Meanwhile, DIW of the respective gels led to meshes with up to 60% wet stretchability. The LCF and meshes were demonstrated to have reliable performance in marine environments. As a demonstration, we show the prospects of replacing plastic cords and other materials used to restore coral reefs on the coast of Mexico.

The weight loss for all samples indicates degradation in the temperature range tested, exhibiting a weight loss > 80 % for temperatures above 200 °C. LCF samples showed two degradation steps; attributed to cellulose and lignin degradation products, respectively. 1 The main peak attributed to cellulose degradation appears above 200 °C with a maximum of 280 °C; this peak merges with the lignin degradation peak at around 350 °C. From Figure S6 is evident that the lignin peak becomes sharper and wider for samples with higher lignin content; moreover, the ash content for LCF samples (A, B, C) were 20, 19, and 9 %, respectively. In contrast, the pretreated pulp samples ( Figure S6d) exhibited the same trend as the regenerated samples but with a peak that overshadowed the cellulose degradation peak attributed to hemicelluloses and lignin. The lignin peak appears shifted around 10 °C compared to the LCF samples (maximum around 360 °C). S7 Figure S7. LCF sample surfaces A, B, and C used for color, gloss, and iso-brightness tests LCF from sample A were used to tie fragments of the coral species Agaricia tenuifolia to the electrolytic mineral accretion coral habitat aka artificial reef. 2 The strength and pliability of the filament for one month were monitored to verify that these filaments will support multiple applications for coral and marine biodiversity regeneration. The purpose is that the coral will cement itself to the structure, and in time when the filament biodegrades, it will not add pollutants to the ocean environment.

Liquid fraction analysis by High-Performance Liquid Chromatography (HPLC)
The HPLC-UV-RID analyses were carried out in a

Analytical Pyrolysis coupled to Gas Chromatography-Mass Spectrometry (Py-GC/MS)
The solid samples from chemical fractionation (lignin-rich and cellulose-rich fractions in proportionality between the area of the chromatographic peaks corresponding to a particular compound and its relative concentration. Based on this principle, the selectivity was S15 estimated by the ratio between the chromatographic peak area of a ith-compound (PArea i ) and the sum of total detected peak areas (PArea i ) (Equation S1). (S1) Solid fractions from solvolysis were characterized by Fourier-Transform Infrared Spectroscopy (FTIR). The IR spectra were recorded over 32 scans in the range 4000 cm -1 to 400 cm -1 , with a resolution of 2 cm -1 using a Nicolet is20 spectrometer (Thermofisher, USA) and a Specac Quest ATR accessory equipped with a Ge crystal (Specac, UK). The spectra were post-processed and analyzed using the Omni Specta software (v2013).

Kraft pretreatment
The kraft process allows the fragmentation and solubilization of lignin to obtain cellulosic pulp using a solution of sodium hydroxide (NaOH) and sodium sulfide (Na 2 S), expressed as active alkali and sulfidity in NaOH basis. BPw were cut into chips (small pieces of 3 cm to 5 cm in length).

Rheology properties
The shear rheology of the dissolved lignocellulose material was monitored in the steady and oscillatory modes using an Anton Paar Physica MCR 302 (Anton Paar GmbH, Austria) rheometer equipped with a Peltier hood H-PTD 200 for controlled temperature and humidity; all the measurements were performed at 60 o C. The tests were carried out with a parallel plate geometry of 25 mm diameter and 1mm gap, viscosity measurement, frequency swept study at 0.1 % amplitude, and cross-over point was studied. % prevented a proper mixing during the dissolution process due to the high viscosity. The sample D at 3 % w/w was prepared specially for the 3D printing process since lower S17 viscosities were required for a proper extrusion on the device. The dopes were homogenous, and a filtration step (50 µm mesh) was included before the spinning and 3D printing steps.

Wet spinning and 3D-printing
The The shear rates during the wet spinning and 3D printing process can be calculated using plug flow approximation. 6 For the spinning conditions, the shear rate is approximately 35 s -1, and for the printing process, 8 s -1 .
The filaments and 3D printing structures drying and stretching properties were calculated according to the following equations: where L is the material reference dimension (for LCF diameter), Equation S2 was used to measure the LCF, and 3D printed materials shrinkage after drying with reference to the freshly extruded material dimensions, Equation S3 was used for measuring the swelling after overnight immersion in water of the previously dried materials. The stretching percentage was measured after extending the material and analyzing its final length before the break (using the tensile test equipment).

Mechanical performance, structure, and thermal behavior
LCF's mechanical properties were studied using a Universal Tensile Tester Instron 4204, 100 N load cell, test speed 5 mm/min. According to the ASTM D3822/D3822M standard, samples were prepared and analyzed. The thickness of dry and wet samples (immersed in deionized water overnight) was measured using a digital micrometer (Mitutoyo, Japan) and repeated five times in different positions; wet samples were measured by placing the samples between glass slides. 7 Ten replicas of each sample were taken for the mechanical tests. where I t is the total intensity of the (0 0 2) peak for cellulose I and I a is the intensity assigned to the amorphous cellulose.
The thermal stability of the samples was studied using a thermogravimetric analyzer (sensitivity of 0.001 mg) (TA instruments, Q500, USA). Around 10 mg of each sample were placed in the thermogravimetric analysis under Nitrogen flow (60 ml/min). The programmed temperature procedure is maintained at 30 °C for 15 min, then increased to 700 °C (ramp rate 10 °C·min -1 ) and finally kept at 700 °C for 30 min.