The Synergy between Bio-Aggregates and Industrial Waste in a Sustainable Cement Based Composite

The effects of the fly ash and of the sunflower stalks and corn cobs within a cement-matrix composite were studied under the aspects of density, compressive strength, splitting tensile strength, elasticity modulus, and resistance to repeated freeze-thaw cycles. In the research were developed 20 recipes of cement-based composite, including the reference composite. Fly ash was used as partial cement replacement (10, 20 and 30% by volume), and the vegetal aggregates made by corn cobs and sunflower stalks as partial replacement of the mineral aggregates (25 and 50% by volume). The study results revealed that a lightweight composite can be obtained with 50% of vegetal aggregates, and the fly ash, no matter its percentage, enhanced the compressive strength and splitting tensile strength of the compositions with 50% of sunflower aggregates and the freeze-thaw resistance of all compositions with sunflower stalks.

COMPARISON OF PROPERTIES OF CELLULOSE NANOMATERIALS OBTAINED FROM SUNFLOWER STALKS

This study aimed to investigate the usability of sunflower stalks, which is one of the most significant agricultural residues in Turkey, in the production of cellulose nanomaterials (CNMs). Cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were produced by using a grinding method and acid hydrolysis, respectively. The average width and length of CNCs were found as 13.91 ± 3.09 nm and 60.44 ± 21.06 nm, respectively. Besides, the average width of CNFs was determined as 15.03 ± 3.68 nm. The crystallinity index of CNFs and CNCs was determined as 82.64% and 83.09%, respectively. Although the main thermal degradation stage of CNCs started at higher temperature than that of CNFs, the latter were more stable than CNCs at high temperatures. Furthermore, the chemical bonds in the raw material, bleached fiber, CNCs and CNFs were investigated with FTIR analysis. Consequently, it was seen that sunflower stalks can be a suitable raw material for the production of CNMs.

Sunflower Stalks versus Corn Cobs as Raw Materials for Sustainable Concrete

Concrete, the most common material in the building industry, involves the use of mineral aggregates that represent an exhaustible resource, despite their large availability. For a series of applications, these mineral aggregates can be replaced by vegetal ones, which represent an easy renewable natural resource. In this study, two types of vegetal raw materials, namely sunflower stalks and corn cobs, were used in developing 10 compositions of ecological microconcrete, with different percentages involved: 20%, 35%, 50%, 65% and 80%; they were analyzed from the perspectives of density, compressive strength, splitting tensile strength, resistance to repeated freeze-thaw cycles, modulus of elasticity and thermal conductivity. The results revealed that the microconcretes with sunflower stalks registered slightly higher densities and better results regarding the compressive strength, splitting tensile strength, modulus of elasticity, and freeze-thaw resistance than those with corn cobs. Lightweight concrete is obtained when more than 50% replacement rates of the mineral aggregates are used.

Allelopathy of vegetable residues on the sowing properties of soft winter wheat grain

Aim. To study the allelopathy of vegetable residues on sowing properties of soft wheat grain. Methods. Laboratory, mathematical and statistical, physical. Results. The highest germination energy was obtained in the variant with water, corn and wheat stalks – 100%, percentage germination was 95%. Under conditions of germination in rye, rape and oat stalks, percentage germination was 15–30 % points lower compared to the control. Germination of soft wheat grain in the stalks of other crops provided percentage germination of 15–50 %. Obviously, soybeans, sunflowers, mustard, peas, barley, flax, safflower, buckwheat and sorghum show high allelopathy during the germination of soft wheat grain. The highest seedling vigor was obtained during germination in water and in corn stalks – 50 %. This figure in wheat and rye stalks was 33 and 28 %, respectively, or 17–22 points lower than the control. During the germination of soft wheat grain in the stalks of other crops, the seedling vigor was the lowest – 8–22 %. The average germination rate varied inversely proportional to seedling vigor. On average, wheat grain in corn stalks germinated for 29 minutes which was at the control level. During germination in wheat and rye stalks, it grew for up to 43–58 minutes. During germination in the stalks of other crops, the average speed increased to 72–288 minutes. Different germination substrates changed the parameters of soft wheat stalks. This indicator was at the level of control over grain germination in rye and corn stalks – 9.2–9.3 cm with fluctuations from 8.1 to 10.3–10.4 cm, and the variation coefficient was small (V = 12.0–12.5 %). The stalk length was significantly shorter during germination in wheat stalks, but the variation coefficient was insignificant (V = 5.2 %). During germination in the stalks of other crops, the stalk length decreased from 7.3 to 0.6 cm. Coclusions. Germination of wheat grain in corn and wheat stalks did not affect the deterioration of germination. The lowest allelopathy was shown by grain germination in rye stalks. The highest allelopathy was shown by germination in soybean and sunflower stalks. Crops, according to the influence on the length of soft wheat stalk, are arranged in the following order: sunflower, buckwheat, sorghum, safflower, soybean, mustard, flax, oats, rape, barley, peas, wheat. Grain germination in corn and rye stalks did not affect the length of soft wheat stalks

Effects of Forces, Particle Sizes, and Moisture Contents on Mechanical Behaviour of Densified Briquettes from Ground Sunflower Stalks and Hazelnut Husks

Using the uniaxial compression process, the mechanical behaviour of densified briquettes from ground sunflower stalks and hazelnut husks was studied under different forces (100, 200, 300, and 400 kN), particle sizes (0, 3, 6, and 10 mm), and moisture contents (sunflower; 11.23%, 14.44%, and 16.89% w.b.) and (hazelnut; 12.64%, 14.83%, and 17.34% w.b.) at a constant speed of 5 mm min−1. For each test, the biomass material was compacted at a constant volume of 28.27 × 10−5 m3 using a 60 mm-diameter vessel. Determined parameters included densification energy (J), hardness (kN·mm−1), analytical densification energy (J), briquette volume (m3), bulk density of materials (kg·m−3), briquette bulk density (kg·m−3), and briquette volume energy (J·m−3). The ANOVA multivariate tests of significance results showed that for ground sunflower stalk briquettes, the force and particle size interactions had no significant effect (p > 0.05) on the above-mentioned parameters compared to the categorical factors, which had a significant effect (p < 0.05) similar to the effects of forces, moisture contents, and their interactions. For ground hazelnut husk briquettes, all the factors and their interactions had a significant effect on the determined parameters. These biomass materials could be attractive for the briquette market.

Sustainable Development of Human Society in Terms of Natural Depleting Resources Preservation Using Natural Renewable Raw Materials in a Novel Ecological Material Production

In the last few years, the building industry experienced a significant development as a response to the demographic growth of human society and to the increasing demand for housing. Their construction involves the traditional use of concrete as a material that provides added strength to the finished building. This is manufactured respecting standard recipes depending on the way of its use. Anyway, all concrete recipes involve the use of mineral aggregates extracted from the riverbed, as is happening in Romania, or rock blocks crushing, as reported in other countries. Under these conditions, the rationalization of the use of natural mineral resources and the identification of new possibilities to reduce their consumption through their replacement with vegetal waste has become an important research issue. In this study, two types of vegetal waste—namely, shredded corn cobs and sunflower stalks—were used to manufacture novel ecological concretes. The vegetal wastes, both in untreated and treated forms (with 20% and 40% of sodium silicate solution), were used to replace 50% of the river (mineral) aggregate volume. The obtained concretes were tested, and the values of some important parameters in the concrete characterization (such as bulk density, water adsorption capacity, compressive strength and splitting tensile strength) were compared with the concrete contains cement CEM II/A-LL 42.5R. The obtained results show that these vegetal wastes have the potential to be used in the manufacturing of new ecological concrete. In addition, this alternative material meets the requirements for the sustainable and healthy development of the environment, offering low-polluting solutions in the context of an increasing demand for constructions.

Sunflower (Helianthus Annuus) Stalks as Alternative Raw Material for Cement Bonded Particleboard

Sunflower stalks (Helianthus annuus) were studied as an alternative raw material for cement bonded particleboard. Experimental cement bonded particleboards measuring 500 mm × 500 mm × 12 mm with nominal density of 1300 kg/m3 were produced using different ratios of sunflower stalk particles with wood. Properties of the cement bonded particleboards evaluated include water absorption, thickness swelling, screw withdrawal strength and bending properties. Results of the study showed that the addition of small amount of sunflower stalks in the production of cement bonded particleboard does not significantly influence the properties tested. Inclusion of more stalks in the mixture significantly decreases mechanical properties and raises thickness swelling and water absorption values of the cement bonded particleboard. Results indicate that boards which include a small amount of sunflower stalks provide properties required by the standards for general purpose-use cement bonded particleboards.

Xylitol Production from Agricultural Wastes by Candida tropicalis

Xylan produced various agricultural residues including wheat (Furat, Abugraib and Abaa), Papyrus and Sunflower stalks in different ways, including the use of diluted acid, dilute base and self-degradation. The results showed that the acidic method in the production of xylan from various agricultural residues compared with other methods was superior, the highest quantity of xylan 187.6 µg.ml-1 was obtained from the agricultural waste of Papyrus, while it was 157.6, 157.6, 161.6 and 161.3 µg.ml-1 of wheat category of furat, wheat Abu Ghraib, wheat Abaa and sunflower stalks respectively, based on the results obtained, the xylan produced by the acidic method of the different agricultural residues was selected to determine the optimal carboon source for production of xylanase using bacteria Bacillus subtilis strain RS1 locally isolated. After the production of xylitol, the descriptive diagnosis was performed using an HPLC device, depending on the time of the 38.4 minute time lapse reaction of the standard Xylitol and compared with the time of the production of Candida tropicalis, the amount of the processed xylitol was 8.3 µg.ml-1, the calculated xylitol was compared standard xylitol