Technical Field of the Invention

The invention relates to an environmentally friendly and cost-effective method for biopolyol production. In other words, the invention relates to obtaining biopolyol from biological sources with a more environmentally friendly and cost-effective method as an alternative to the acid- catalyzed solvothermal liquefaction method in the state of the art. In the method subject to the invention, biopolyol production is carried out in a step-by-step (gradual) process, and the biopolyol obtained in each step is used as a solvent in the next liquefaction process (for obtaining the next-generation biopolyol) completely or by blending with the petroleum-based solvent mixture (SM). In this way, costly petroleum-based solvents used in every (single step) acid-catalyzed solvothermal liquefaction batch process of biomasses is avoided and with this step-by-step process, the use of costly petroleum-based solvents for next-generation biopolyol production(s) is minimized or completely eliminated.

State of the Art

Polyols are reactive raw materials containing at least two hydroxyl functional groups and forming polyurethane (PU) by reacting with isocyanate (NCO) groups through these groups. Polyols are very important components for polyesters as well as polyurethanes. Polyols, which act as chain extenders in the polymer formation process, greatly control the mechanical, thermal and physical properties of the final material, and can also reduce the total cost. In today’s world, the need for polyols is increasing day by day. The reason for this is the need for polymer-based products in which polyols are used in all fields where technology and quality of life/we 11 -being are required in human life. For example, polyurethanes obtained from polyols are known as a unique group of polymers that are used extensively in areas such as transportation, construction, furniture industry and mining due to their wide range of properties.

One of the most important components of polyurethane production is polyols, and it is seen that these reagents have been produced from petroleum -based sources in the historical process, however, they have started to be produced from biomass in recent years. Polyols are of great importance in determining the physico-mechanical properties of the final product. The hardness or elasticity, chemical resistance and gas and moisture permeability degrees of polyurethane foam are largely determined by the polyols used. Although polyols can be synthesized with different chemical approaches from various biomasses with easy and quick processes, there are still some aspects related to the issue which are open to improvements.

Today, many researchers and industrial organizations have focused on replacing petroleumbased resources with renewable resources in order to increase the sustainability of polyurethane production due to increasing concerns about the environment, rapid depletion of oil and increasing legal regulations related to these. At this point, various biomasses emerge as the most important alternative polyol sources. In the present technique, polyols obtained from biomass are called “biopolyols”.

In the state of the art, high amounts of petroleum -derived polyhydric alcohols (ethylene glycol, polyethylene glycol 400 (PEG400), etc.) are still used as solvents in the production of biopolyol from cellulose/lignocellulose-containing biomass by acid-catalyzed solvothermal liquefaction method. The fact that (bio)polyols, which can be an alternative to these petroleum-based solvents, can be produced with an approach that is both more environmentally friendly and cost-effective, is important not only for the PU industry but also for other polymer industries where these inputs are used. The use of petroleum-based solvents in the biomass liquefaction process also imposes huge economic costs on businesses. For all these reasons, the search to obtain biopolyol with a more cost-effective and environmentally friendly approach continues all over the world.

Patent application no. KR101893878B1 mentions a biopolyol (biomass content of 90% and above) obtained using castor oil and a PU foam formulation including this biopolyol. The PU foam formulation comprises of a petroleum-based polyol, a biopolyol, a cell opener, an amine- based catalyst, a surfactant, a foaming agent, petroleum based diisocyanate and bioisocyanate. Petroleum-based polyol is obtained by mixing a diol polyol and a triol polyol with a ratio of 1: 10-1:20. The production method of the PU formulation obtained using a high ratio of biomass content subject to the patent application includes the following steps; i) preparing a resin premixture by mixing a petroleum-based polyol, a biopolyol, a cell opener, an amine-based catalyst, a surfactant and a foaming agent, ii) synthesizing isosorbide diol lactate (ISB di (lactate)) by reaction of isosorbide diol with lactate, and then synthesizing the NCO-pre- polymer to prepare a bioisocyanate, and iii) mixing and reacting the bioisocyanate with the resin premixture, respectively.

Although biomass is used in polyol production in the state of the art, petroleum-based polyhydric alcohols are used as solvents in biopolyol production by the acid-catalyzed solvothermal liquefaction process from biomass. It is not possible to find any studies to reduce the costs of using petroleum-based solvents in the state of the art. In other words, biopolyols in the state of the art can only be obtained as a result of costly processes.

Due to reasons such as the fact that costly petroleum-based polyhydric solvents are used in each liquefaction process in biopolyols production, and the lack of a cost-effective and sustainable approach in the liquefaction processes of biopolyols obtained from biomass in the known state of the art, it is necessary to develop a method in which all of these problems are eliminated, biopolyol is obtained from biological sources with a more environmentally friendly and cost-effective method, and it is possible to obtain biopolyol that maintains the sufficient quality required for the relevant fields of application/use.

Brief Description and Objectives of the Invention

The invention describes an environmentally friendly and cost-effective method for biopolyol production. In other words, it is described in the invention that biopolyol production from biological sources is carried out by a more environmentally friendly and cost-effective method as an alternative to the acid-catalyzed solvothermal liquefaction method in the state of the art, which is one step (batch) process and every batch requires the use of costly petroleum-based solvents. In the method subject to the invention, biopolyol production is carried out in a step- by-step (gradual) process, and the biopolyol obtained in each step is used as a solvent in the next liquefaction process (for obtaining the next-generation biopolyol) completely or by blending with the petroleum-based solvent mixture (SM). In this way, costly petroleum-based solvents used in every (single step) acid-catalyzed solvothermal liquefaction batch process of biomasses is avoided and with this step-by-step process, the use of costly petroleum-based solvents for next-generation biopolyol production(s) is minimized or completely eliminated. To summarize, it is an invention that defines a more environmentally friendly and more cost- effective polyol production method since i) it employs biopolyol by a step-by-step (gradual) process and uses biopolyol obtained in each step as a solvent in the next liquefaction process completely or partially (by blending with the solvent mixture (SM)), and ii) the amount of petroleum-based solvent needed in liquefaction processes is much reduced compared to the state of the art.

The objective of the invention is to provide a cost-effective method for biopolyol production that requires less cost compared to the state of the art. The realization of biopolyol production with a more cost-effective approach is provided by the biopolyol production method of the invention. Since the biopolyol obtained in each step in the biopolyol production method of the invention is utilized as a solvent in the next liquefaction process (for obtaining the nextgeneration biopolyol) or by blending with the solvent mixture (SM), the costly and petroleumbased solvent use of the biomass in the liquefaction process is minimized or completely eliminated in the biopolyol production(s) in the next generation.

Another objective of the invention is to provide a more environmentally friendly method for biopolyol production compared to biopolyol productions in the state of the art. The realization of biopolyol production with a more environmentally friendly approach is provided by the biopolyol production method of the invention. While it is necessary to use costly petroleumbased solvents at the beginning of each biopolyol production in the state of the art, since the biopolyol obtained in each step in the biopolyol production method subject to the invention is utilized as a solvent in the next liquefaction process (for obtaining the next-generation biopolyol) or by blending with the solvent mixture (SM), the use of petroleum-based solvents in the liquefaction process with the method subject to the invention completely eliminates or minimizes the use of scarce petroleum resources in the next generations, and paves the way for the efficient use of these resources.

Descriptions of the Figures

Figure 1. 3-factor central composite design, a= central point, b=cube points, c=axial points Figure 2. Comparison of experimental and estimated liquefaction yield (LY)

Figure 3. 3D response surface (a) and contour (b) graphs showing the dependence of the liquefaction yield (LY) on the catalyst amount and/or reaction time

Figure 4. 3D response surface (a) and contour (b) graphs showing the dependence of the liquefaction yield (LY) on the catalyst amount and/or reaction temperature Figure 5. 3D response surface (a) and contour (b) graphs showing the dependence of the liquefaction yield (LY) on the reaction time and/or reaction temperature

Detailed Description of the Invention

The invention relates to an environmentally friendly and cost-effective method for biopolyol production. In other words, the invention relates to obtaining biopolyol from biological sources with a more environmentally friendly and cost-effective method as an alternative to the acid- catalyzed solvothermal liquefaction method in the state of the art. In the method subject to the invention, biopolyol production is carried out in a step-by-step (gradual) process, and the biopolyol obtained in each step is used as a solvent in the next liquefaction process (for obtaining the next-generation biopolyol) completely or by blending with the petroleum-based solvent mixture (SM). In this way, costly petroleum-based solvents used in every (single step) acid-catalyzed solvothermal liquefaction batch process of biomasses is avoided and with this step-by-step process, the use of costly petroleum-based solvents for next-generation biopolyol production(s) is minimized or completely eliminated.

In this method subject of the invention which is aimed at biopolyol production, firstly olive mill pomace (OMP), which is an olive oil industry waste, is converted into biopolyol (main biopolyol) by using a mixture of petroleum -based polyhydric alcohols polyethylene glycol 400 (PEG400) and glycerin (solvent mixture containing 80% PEG400 by mass, SM) as a liquefaction solvent by acid-catalyzed solvothermal liquefaction method, and then the main biopolyol obtained is used as a liquefaction solvent (completely or partially substituted instead of solvent mixture (SM)) in the next olive mill pomace (OMP) liquefaction process. An approach such as “generation derivation” or “generation transfer” is applied in the production of biopolyols after the main biopolyol. In other words, the biopolyol obtained is used in the next liquefaction process and thus the need for costly petroleum-based solvents used in the state of the art is eliminated or reduced. Minimizing the use of costly petroleum-based liquefaction process solvents ensures that biopolyols are obtained with an environmentally friendly and cost-effective approach.

Production method of a 1st generation biopolyol using petroleum-based solvent mixture (SM) only once involves the following process steps; i. subjecting the biomass to solvothermal liquefaction process in the solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerine by mass, accompanied by a 2-6% sulfuric acid (H2SO4) catalyst, for 20-100 minutes at 130-170°C, with a biomass: liquefaction solvent ratio of 1 :4, and thus obtaining a main biopolyol, ii. obtaining the 1st generation biopolyol as a result of using only the main biopolyol as the liquefaction solvent in the liquefaction of the biomass, or (b) obtaining the 1st generation biopolyol as a result of mixing 50-75% of the main biopolyol with the solvent mixture (SM) in complementary ratio and using it as the liquefaction solvent in the liquefaction of the biomass.

In another embodiment of the invention, the process step no. (i) is subjecting the biomass to solvothermal liquefaction in a solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerine by mass, accompanied by a 3.8% sulfuric acid (H2SO4) catalyst, for 62 minutes at 170°C, with a biomass: liquefaction solvent ratio of 1:4, and thus obtaining the main biopolyol.

In another embodiment of the invention, the method of producing a 2nd generation biopolyol by the production from biomass approach involves the following process steps; i. subjecting the biomass to solvothermal liquefaction process in a solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerin by mass, accompanied by a 2-6% sulfuric acid (H2SO4) catalyst, for 20-100 minutes at 130-170°C, with a biomass: liquefaction solvent ratio of 1:4, and thus obtaining the main biopolyol, ii. obtaining the 1st generation biopolyol as a result of mixing 60% main biopolyol with 40% solvent mixture (SM) in complementary ratio and using it as liquefaction solvent in liquefaction of biomass, iii. obtaining the 2nd generation biopolyol as a result of mixing 60% 1st generation biopolyol with 40% solvent mixture (SM) in complementary ratio and using it as liquefaction solvent in liquefaction of biomass.

In another embodiment of the invention, in the process step no. (i) is subjecting the biomass to solvothermal liquefaction in a solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerin by mass, accompanied by a 3.8% sulfuric acid (H2SO4) catalyst, for 62 minutes at 170°C, with a biomass: liquefaction solvent ratio of 1:4, and thus obtaining the main biopolyol. In another embodiment of the invention, the method of producing respectively 2nd, 3rd and 4th generation biopolyol by the production from biomass approach involves the following process steps; i. subjecting the biomass to solvothermal liquefaction process in a solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerine by mass, accompanied by a 2-6% sulfuric acid (H2SO4) catalyst, for 20-100 minutes at 130- 170°C, with a biomass: liquefaction solvent ratio of 1:4, and thus obtaining the main biopolyol, ii. obtaining the 1st generation biopolyol as a result of mixing 50% main biopolyol with 50% solvent mixture (SM) in complementary ratio and using it as liquefaction solvent in liquefaction of biomass, iii. obtaining the 2nd generation biopolyol as a result of mixing 50% 1st generation biopolyol with 50% solvent mixture (SM) in complementary ratio and using it as liquefaction solvent in liquefaction of biomass, iv. obtaining the 3rd generation biopolyol as a result of mixing 50% 2nd generation biopolyol with 50% solvent mixture (SM) in complementary ratio and using it in liquefaction of biomass as liquefaction solvent, v. obtaining the 4th generation biopolyol as a result of mixing 50% 3rd generation biopolyol with 50% solvent mixture (SM) in complementary ratio and using it in liquefaction of biomass as liquefaction solvent,

In another embodiment of the invention, the process step no. (i) is subjecting the biomass to solvothermal liquefaction in a solvent mixture (SM) consisting of 80% polyethylene glycol 400 (PEG400) and 20% glycerin by mass, accompanied by a 3.8% sulfuric acid (H2SO4) catalyst, for 62 minutes at 170°C, with a biomass: liquefaction solvent ratio of 1:4, and thus obtaining the main biopolyol.

In Table 1 below, the hydroxyl number, acid number, viscosity and liquefaction yield (LY) values of the biopolyols produced within the process steps in the biopolyol production method of the invention are given. As can be clearly understood from the table, the liquefaction efficiency of the main biopolyol was 92.9%, while this value varied between 88.6% and 95.8% for the lst-4th generation biopolyols produced by the generation derivation method. Table 1. Characteristics of biopolyols obtained by the method subject to the invention. In the biopolyol production method subject to the invention, sulfuric acid (H2SO4) was used as a catalyst and the biomass: liquefaction solvent ratio was kept constant as 1:4. The biomass used in the biomass-based biopolyol production method subject to the invention is olive mill pomace (OMP). In addition, sugar beet, tomatoes and red pepper, aromatic plants such as lavender and thyme, cultivated mushrooms, algae, peas, kidney beans, com, eucalyptus, various types of woody trees (poplar, cypress, birch, linden, olive, chestnut, pear, oak, white hornbeam, ash tree, walnut, elm, maple, alder, acacia, Calabrian pine, scotch pine, black pine, nut pine, Aleppo pine, maritime pine, cherry, fir, spruce, juniper, mulberry, boxwood, pavilion, paulownia, willow, eucalyptus), rice, wheat, sugar cane, rapeseed, coffee, cotton, citrus, cashew nuts, soy, hazelnut, oats, bananas, beans, plants containing cellulose/lignocellulose such as soybeans and barley and parts of these plants such as the stem, bran, straw, sediment, pulp, core, root, grounds, shell, seeds, etc. can also be used instead of olive mill pomace (OMP).

Traditional and modem optimization methods are frequently used to determine which parameter affects the reaction (or transformation) efficiency of obtaining biopolyol from lignocellulose-containing biomass. In traditional optimization methods, the most appropriate variable parameters are determined by conducting a large number of experiments. However, in this case, a process optimization can be achieved, which is generally low in precision and accuracy, with disadvantages such as long working time, heavy labor and high costs. On the other hand, it is possible to both increase efficiency and reduce costs by conducting fewer number of experiments with modem optimization methods. Although there are various modem optimization methods, the response surface method (RSM) is one of the most preferred experimental design and optimization methods.

RSM is a blend of statistical and mathematical techniques to develop, improve and optimize any process, product design, system or experiment. The most important advantage of this method is that the effect of a large number of parameters can be evaluated at the same time and the number of experiments can be reduced. However, it also has advantages such as examining the interactions of independent variables with each other and expressing the relationship between independent variables and the response by defining the system with a mathematical model. RSM consists of following stages: i) determining the independent variables and the minimum and maximum values of these variables, ii) conducting experiments according to the determined parameters, iii) creating a mathematical model against the received process response and determining the optimum experimental parameters, iv) conducting validation studies according to the determined optimum values, and v) drawing three-dimensional response surface and contour graphics with computer-aided software programs.

The effects of various factors on a response based on experimental results obtained from design with RSM are usually described by constructing a quadratic polynomial equation. The said equation is shown below.

In this equation, y is response, /? ₀ is cutting point, is linear coefficient, ?,, is quadratic coefficient, is interaction coefficient and Xi is coded factor levels.

Creating the most accurate model is possible by choosing the most appropriate experiment design. Although there are various methods within the scope of RSM, central composite design (CCD) is one of the most preferred methods. The CCD, which is usually proposed for the design of experiments to be performed consecutively, is a full factorial design plan with five levels. These levels are discussed in three parts: two factorial (level) points, two asterisk (axial) points, and one central point. When estimating quadratic equations with central and axial points, it is easy to estimate the square terms in the model with orthogonal blocking and rotatability properties. Orthogonal blocking allows model terms and block effects to be estimated independently of each other and reduces the variation between regression coefficients, while rotatability increases the predictive quality of the model by equating the distances between the central point and other points.

While the distance for each factor from the central point of the design to a factorial point is ±1, the distance for each factor from the central point to a star point is ± a (|a|>l). a varies depending on the desired characteristics and number of factors for the design. The value of a depends on the number of experiments to obtain the rotatability. a= [Number of Experiment] ^(1/4)

If the design is full factorial, it is shown as follows; a=[2 ^k ] ^(1/4)

Where k is the number of factors determined for the design.

In the CCD method, the number of experiments to be performed is determined by the following equation.

Total number of experiments=2 ^k + 2k + mo

Here, k refers to the number of factors determined for the design, 2 ^k refers to the number of experiments corresponding to the comer points of the cube, 2k refers to the number of experiments corresponding to the axial points of the cube, and mo refers to the number of experiments performed for the central point. The main effects and first-order interactions of the quadratic equation created from the CCD model are determined from the 2k experiments, while the curvature of the equation is determined with the help of central points. In order to determine the suitability of the model, the responses obtained as a result of experimental studies are analysed using the ANOVA test. Figure 1 shows the 3-factor central composite design. Each circle in Figure 1 refers to an experiment.

CCD is one of the most preferred design methods to investigate the synergistic effect of different variables on a target parameter among response surface methods. In this study, the 3- variable and 5-level experimental design was used to optimize the process parameters for obtaining biopolyol from olive mill pomace (OMP) by acid-catalyzed solvothermal liquefaction method using Minitab® 19 statistical software (Minitab Inc., Pennsylvania, USA). In line with the available literature, the variables were selected as: amount of catalyst (A), reaction time (B) and reaction temperature (C). The experimental range and levels of the variables are explained in Table 2, and the experimental design and experimental order are given in Table 3. This design consists of a total of 17 experiments. Here, the curvature of the model created is determined thanks to the central points, while experimental errors and noncompliance are determined by the factorial points. Table 2. Experimental ranges and levels of independent variables.

Table 3. CCD matrix and experimental liquefaction yield (LY) results for biopolyol acquisition. a; in order to obtain a stronger model, this model was accepted as an outlier model.

The highest liquefaction yield (LY) of 95.5% was obtained with the experiment where the liquefaction conditions were 5% catalyst, 160°C and 80 minutes. The high value of liquefaction yield (LY) supports the effectiveness and feasibility of obtaining biopolyol from waste olive mill pomace (OMP) by solvothermal liquefaction. The quadratic polynomial equation showing the correlation between the liquefaction yield (LY) responses obtained as a result of this study and the reaction parameters (independent variables) is shown below. ysv=84,254 + 4,034A + 2,267B + 5,331C - 0,742A ² - 0,803B ² + 0,197C ² - 0,597AB + 0,460AC + 0,185BC

• ysv: liquefaction efficiency (%)

• A: catalyst amount (% by mass)

• B: reaction time (min)

• C: reaction temperature (°C)

The positive coefficients of the variables in the equation have an effect on increasing the liquefaction yield (LY) in the studied range, while the negative coefficients cause the liquefaction yield (LY) to decrease. ANOVA results are summarized in Table 4. Table 4. Variance analysis for the regression model of liquefaction efficiency (ANOVA)

R ² =0,9935, Corrected-R2=0,9835 Estimated-R2=0,9363, RSD=0,8887

Errors that occur during the liquefaction process may cause discrepancies in the model. In order to obtain a stronger model, the experiments in which these errors occur can be excluded from the list. Therefore, the experimental study coded Dl l was excluded from the model. The F- value of the model as 102.34 indicates that the model is extremely significant. The p-value is used to determine whether each term in the model is significant. The fact that the p-value of the relevant term is greater than 0.05 indicates that such term is insignificant. As can be seen from Table 4, the p-values of the catalyst amount-reaction time, catalyst amount-reaction temperature, reaction time-reaction temperature interactions were observed to be 0.106, 0. 194, 0.578, respectively, and as a result, these interactions were found to be insignificant. Terms with a p-value less than 0.05 are significant for the model. Noncompliance indicates whether the model studied is sufficient. The p-value of the noncompliance (0.281) indicates that the relevant term is insignificant for the model, and that the proposed model complies with the

2 experimental results. The high regression coefficient value (R = 0.9935) supports the accuracy and reliability of the model. In addition, the estimated regression coefficient (Estimated-

2

R =0,9363) being greater than 0.5 indicates that the model is good. Insignificant terms can be removed to increase the accuracy of the model, however, these terms have not been removed

2 from the model because the regression coefficient (R = 0.9935) is quite high. When the results are examined, it is seen that the most effective parameter in the biopolyol conversion of olive mill pomace (OMP) is the reaction temperature. The effects of other parameters on the liquefaction process are the amount of catalyst (A) and reaction time (B), respectively. In the graph in Figure 2, experimental and estimated liquefaction yields (SV) were compared. When the graph in Figure 2 is examined, it is seen that the data points are close to the regression line and the relationship between the estimated values and the experimental values is compatible.

Optimization of solvothermal liquefaction method parameters

Based on the regression equation (the aforementioned quadratic polynomial equation) obtained as a result of the experimental data, three-dimensional (3D) response surface and contour graphs were created using the interface of the Minitab software and these graphs are presented in Figures 3, 4 and 5.

While one of the factors was kept constant at the central point in Figures 3, 4 and 5, the effects of the other two specific factors on the response were examined. The curve shapes in all the graphs obtained are convex downwards, indicating a maximum response for liquefaction yield (LY). The graphs a and b in Figure 3 indicate the effect of the amount of catalyst (A) and reaction time (B) on the liquefaction yield (LY). When the graph (a) in Figure 3 is examined, it is observed that the liquefaction yield (LY) gradually increases with the increase in the amount of catalyst and reaction time. In addition, it can be said that the effect of the catalyst amount on liquefaction yield (LY) is approximately 2 times more dominant compared to the effect of reaction time on LY. The ranges where the liquefaction yield (LY) takes a maximum value are the studies where the amount of catalyst is 4-5% and the reaction time is 60-80 minutes. At the end of these ranges, the liquefaction yield (LY) tended to decrease. As can be understood from the graph (b) in Figure 3, in order for the liquefaction yield (LY) to be higher than 88%, the amount of catalyst must be more than 4.9% and the reaction time must be longer than 45 minutes.

The effects of the amount of catalyst and reaction temperature on the liquefaction yield (LY) are shown in the graphs (a) and (b) in Figure 4. Liquefaction yield (LY) increased rapidly with the increase of the reaction temperature. It is seen that the peak for liquefaction efficiency is reached in the range of 4-5% for the catalyst amount and 150-170°C for the reaction temperature.

The effect of the duration and temperature of the reaction on the liquefaction yield (LY) is shown in graphs (a) and (b) in Figure 5. It is clearly seen in the graphs that the effect of the reaction temperature on increasing the liquefaction yield (LY) is greater than the effect of the reaction time. It has been determined that the ranges where the liquefaction yield (LY) is maximum are 70-90 minutes for reaction duration and 150-170°C for reaction temperature.

As a result, the optimum process parameters for obtaining biopolyol from olive mill pomace (OMP) with the highest efficiency were determined using the developed mathematical model. Accordingly, using the obtained quadratic polynomial equation, it was determined that the optimum conditions for 95% liquefaction efficiency (choosing 95% liquefaction efficiency as the response) were 3.8% for the amount of catalyst, 62 minutes for reaction time and 170°C for reaction temperature. In this study, the primary target was selected as high liquefaction efficiency when determining the optimum process parameters. In addition, low energy and catalyst consumption, short liquefaction time and physicochemical properties of the obtained biopolyol suitable being for the intended use are among the other main objectives.

Validation of the model

Experiments were carried out in 3 repeats at the optimum process conditions determined for the validation of the developed model (amount of catalyst, 3.8%; reaction temperature, 170°C and reaction time, 62 minutes). As a result of the verification experiments, the liquefaction efficiency was determined as 95.07±0.6%. The results obtained support the compatibility of the experimental liquefaction yield (LY) and the estimated liquefaction yield (LY) value. As a result, biopolyol production processes from olive mill pomace (OMP) were optimized using the central composite design (CCD) of the response surface method (RSM).