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Lignin is a natural biopolymer. A vibrant and rapid process in the synthesis of silica nanoparticles by consuming the lignin as a soft template was carefully studied. The extracted biopolymer from coir pith was employed as capping and stabilizing agents to fabricate the silica nanoparticles (nSi). The synthesized silica nanoparticles (nSi) were characterized by ultraviolet–visible (UV–Vis) spectrophotometry, X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Analysis (EDAX), Dynamic Light Scattering (DLS) and Fourier-Transform Infrared Spectroscopy (FTIR). All the results obtained jointly and independently verified the formation of silica nanoparticles. In addition, EDAX analysis confirmed the high purity of the nSi composed only of Si and O, with no other impurities. XRD spectroscopy showed the characteristic diffraction peaks for nSi and confirmed the formation of an amorphous nature. The average size of nSi obtained is 18 nm. The surface charge and stability of nSi were analyzed by using the dynamic light scattering (DLS) and thus revealed that the nSi samples have a negative charge (−20.3 mV). In addition, the seed germination and the shoot and root formation on Vigna unguiculata were investigated by using the nSi. The results revealed that the application of nSi enhanced the germination in V. unguiculata. However, further research studies must be performed in order to determine the toxic effect of biogenic nSi before mass production and use of agricultural applications.

Aim: To evaluate the physical and hydrological properties of different graded coir pith and composted coir pith (CPOM) following the Keen-Raczkowski box and Brunauer-Emmett-Teller (BET) analysis. Methodology: The coir pith was collected and composted by PITH PLUS (Pleurotus-sajor-caju). Thereafter, the coir pith and composted coir pith were segregated into different groups based on the size of the particles as 1.0 mm (1000 microns), 0.5 mm (500 microns), and 0.25 mm (250 microns). Based on particle size, the hydrological properties of coir pith and composted coir pith were determined. The physical and hydrological properties were estimated by the Keen-Raczkowski box method and Brunauer-Emmett-Teller analysis. Results: Different graded coir pith and composted coir pith of size 0.25 mm showed the highest bulk density (0.60 and 0.48 g cm-3), followed by 0.5 mm size coir pith and composted coir pith, respectively. The highest particle density (0.18 and 0.19 g cm-3) was registered in 1.0 mm coir pith and composted coir pith whereas the lowest particle density was observed in 0.25 mm size coir pith (0.15 g cm-3). The water-holding capacity (817.93 % and 806.97 %) and water in air-dry substrate (25.03 % and 36.094 %) was high in 0.25 mm coir pith and composted coir pith. Interpretation: A 0.25 mm grade of coir pith and composted coir pith showed highest water holding and retaining capacity due to a greater number of small particles being compactly arranged and holding more surface area, and innumerable micropores than other graded particles. Key words: BET analysis, Coir pith, Composted coir pith, Water holding capacity

Biodegradable cellulose aerogels have been successfully prepared from coir fibers using a sulfur-free method and NaOH–urea system. Sulfur was avoided during pretreatment because it is environmentally harmful. Interestingly, these pretreatments had a strong effect on the physical properties of the aerogels produced. Good physical properties of the cellulose aerogels were obtained when the Kappa number, i.e., the lignin content, in the pulp was lower than 14.8. NaOH–urea played an important role in transforming cellulose I to cellulose II and crosslinked cellulose to form an aerogel structure. The aerogel had a macroporous structure, ultralight density, high porosity, good durability, and thermal stability. The aerogel was capable of absorbing 22 and 18 times its dry weight in water and oil, respectively. The material also had a high capacity for methylene blue dye adsorption of up to 62 g/g, which was one hundred times higher than that of adsorbents synthesized from the other natural matters. Therefore, the prepared aerogels have potential for various sorption applications. Graphic abstract

The objective of this study was to characterize the properties of cellulose and CMC synthesized from young and mature coconut coir with different bleaching times (bleaching for the first time; 1 BT, bleaching for a second time; 2 BT, and bleaching for the third time; 3 BT) using hydrogen peroxide (H2O2). The surface morphology, structural information, chemical compositions, and crystallinity of both cellulose and CMC were determined. H2O2 bleaching can support delignification by reducing hemicellulose and lignin, as evidenced by FTIR showing a sharp peak at wave number 1260 cm−1. The cellulose and CMC from coconut coir can be more dispersed and have greater functional characteristics with increasing bleaching times due to the change in accessibility of hydroxyl groups in the structure. The CMC diffraction patterns of coconut coir after the bleaching process showed the destruction of the crystalline region of the original cellulose. The SEM images showed that the surface of CMC was smoother than that of cellulose. The CMCy had a higher water holding capacity (WHC) compared to the CMCm as the bleaching can increase interaction between the polymer and water molecules. Therefore, the best quality of CMC corresponds to CMCy. Based on these findings, bleaching time has a strong effect on the functional properties of cellulose and CMC from coconut coir.

Recently, addition of various natural fibers to high strength concrete has aroused great interest in the field of building materials. This is because natural fibers are much cheaper and locally available, as compare to synthetic fibers. Keeping in view, this current research conducted mainly focuses on the static properties of hybridized (sisal/coir), sisal and coir fiber-reinforced concrete. Two types of natural fibers sisal and coir were used in the experiment with different lengths of 10, 20 and 30 mm and various natural fiber concentrations of 0.5%, 1.0%, and 1.5% by mass of cement, to investigate the static properties of sisal fiber reinforced concrete (SFRC), coir fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC). The results indicate that HFRC has increased the compressive strength up to 35.98% with the length of 20 mm and with 0.5% concentration, while the CFRC and SFRC with the length of 10 mm and with 1% concentration have increased the compressive strength up to 33.94% and 24.86%, respectively. On another hand, the split tensile strength was increased by HFRC with the length of 20 mm and with 1% concentration, CFRC with the length of 10 mm and with 1.5% concentration, and SFRC with the length of 30 mm and with 1% concentration have increased up to 25.48%, 24.56% and 11.80%, respectively, while the HFRC with the length of 20 mm and with 0.5% concentration has increased the compressive strength of concrete but has decreased the split tensile strength up to 2.28% compared to PC. Overall, using the HFRC with the length of 20 mm and with 1% concentration provide the maximum output in terms of split tensile strength. Graphical Abstract Experimental Investigation on the Mechanical Properties of Natural Fiber Reinforced Concrete

Renewable energy-based desalination (RED) technique is gaining more importance over the desalination techniques as it appeared to be a promising technique towards low-cost desalination for sustainable growth as the energy demand towards other developments is continuously increasing. This study aims to incorporate energy storage materials and wick materials in the inclined solar to improve the fresh water produced. In this work, the performance of inclined solar still using coconut coir disk and energy storage material is analyzed experimentally. Characterization results showed that the porosity, absorbency, capillary rise, and heat transfer coefficient of 1-year dried coconut coir disk were found as 73.25%, 2 s, 10 mm/h, and 37.21 W/m 2 K, respectively, which is higher as compared with that of other coconut coir disks. The experimental results on the performance showed that total distillate from novel inclined solar still with hybrid techniques (energy storage materials and wick materials) were recorded as 3645, 4080, 4570, and 4890 ml for 3 months, 6 months, 9 months, and 1 year, respectively. While the total distillate outputs of an inclined solar still with only wick materials were recorded as 2560, 2670, 2930, and 3390 ml for 3 months, 6 months, 9 months, and 1-year coconut coir disk wick materials. The novel hybrid techniques used in the inclined solar still with energy storage materials enhanced the yield from 82.25 to 144.5% than the conventional solar still, whereas the inclined solar still with only wick materials enhanced the yield from 28 to 69.5% than the conventional solar still.

The worldwide resurgence of natural dyes in all fields is due to the carcinogenic effects of effluent loads shed by synthetic industries. Coconut coir ( Cocos nucifera ) containing tannin as a source of natural colorants has been selected for coloration of bio-mordanted silk under the influence of ultrasonic radiations at various dyeing conditions. For extraction of tannin dye from cocos powder, different media were employed, and dyeing variables such as dyeing time, dye bath pH, dyeing bath temperature, and the effect of salts on dyeing were optimized. For achieving new shades with excellent color characteristics, bio-mordants in comparison with chemical mordants were employed. It has been found that acid-solubilized extract after ultrasonic treatment for 45 min has yielded high color strength, when coconut coir extract of 4 pH from 6g of cocos powder, containing 5g/100mL salt solution as exhaust agent, was used to dye silk at 75°C for 65 min. Among bio-mordants turmeric ( K / S =13.828) and among chemical mordants iron has shown excellent results ( K / S =2.0856). Physiochemical analysis of fabric before and after US treatment shows that there is no change in the chemical structure of the fabric. It is found that ultrasonic waves have excellent potential to isolate the colorant followed by dyeing and environmental friendly mordanting at optimal conditions, but also the usage of herbal-based plant anchors, i.e., bio-mordants, has made the natural dyeing process more sustainable and clean.

Accelerated weathering and soil burial tests on biocomposites of various ratios of coir (CF)/pineapple leaf fibres (PALF) with polylactic acid (PLA) were conducted to study the biodegradability, colour, and texture properties as compared with PLA.The biodegradability of a lignocellulosic composite largely depends on its polymer matrix, and the rate of biodegradation depends on many environmental factors such as moisture, light(radiation), temperature and microbes. Biodegradation was evaluated by soil burial and accelerated weathering tests. Changes in physical and morphological properties were observed in the biocomposites after weathering. These results allowed us to conclude that untreated CF/PALF/PLA biocomposites would be a more favourable choice owing to their better biodegradability and are suitable for the suggested biodegradable food packaging applications.