Optimization of extraction techniques for processing and utilization of Cyperus Dichrostachus A. Rich Plant as ber

The Textile industry is an important contributor to the GDP of countries worldwide. Both natural and synthetic fibers are the main raw materials for this sector. Environmental concerns, depletion of non-renewable resources, the high price of oil and limited oil reserves with consumer demand is driving research into cheap, biodegradable, sustainable, renewable and abundantly available green materials. Natural fibers are of the good substitute sources for swapping synthetic fibers and reinforcing polymer matrices because of their contributions in maintaining of ecology, nature of disposal, low energy requirement for processing and sustainability. The current research emphases on evaluating and determining the best extraction methods to process and treat cyperus Dichrostachus A.Rich plant in order to make the fiber suitable for variety of applications. Cyperus Dichrostachus A.Rich plant was treated with two conditions (cold and warm conditions) using statistically planned tests. Process conditions were optimised using central composite design methodology with the experimental design. Under optimised conditions, the strength and fiber yield of CDA fibers were significantly compared. The strength and fiber yield of the fiber was at maximized with optimized conditions and use for valorisation applications.


Introduction
At present, most manufacturing and industrial sectors are fascinated in evolving sustainable development and environmental friendly products (Wang and LV JN, 2007, Debnath, 2020. They are in a paradigm shift to sustainability in all aspects of fashion (Radhakrishnan, 2020), eco-friendly polymer composite manufacturing principles (Balli et al., 2019), eco-friendly building materials production and utilization (Nowotna et al., 2019, Pleitner et al., 2019, organic production systems with the main consumable natural fibers like cotton (Günaydin et al., 2019). The main concern is maintaining natural environment by following friendly production and manufacturing concepts that do not devour any dangerous provisions with no poisonous releases to the natural atmosphere at any circumstances.
The utilization of natural fibers in different applications becomes more issue that is critical. There Moreover, they are becoming common in structural applications (Feng and Malingam, 2019) especially in rope making (Jahangir Ali Fathima Benazir, 2010), and automotive applications like shock absorbers, windshields (Balakrishnan et al., 2019), doors, ceilings (Vijay, 2016, Selvakumar andMeenakshisundaram, 2019). They are also vital sources for reinforcement materials with polymer matrix for small-scale applications (Rajini, 2019).
The varied application of plant fibers is the fact that they have exceptional characteristics of flexibility, eco-friendly nature, low cost, renewability, and accessibility, less harmful effect to human beings, bio degradability, ease of extraction, fabrication and manufacturing, high strength to weight ratio with simple and harmless implementation process as compared with synthetic fibers.
Moreover, natural resources have played foremost role in the economic activities with substantial sustainability to the growth of the world in progress through socio-economic development , Kim et al., 2019, Verma et al., 2019, Tomczak et al., 2007. The maximum utilization of such resources done with new developments and products in advance with preventing environmental pollution and generating employment opportunities followed by improvement of people's living standards. One of the most abundant foundations of such resources has been lignocellulosic materials, have been utilized since 6000 BC available from many plant parts .
Natural fibers are generally extracted with a simple and economical method known as retting process after which they are exposed to different chemical treatment approaches. Normally the makeup of the lignocellulosic fibers consists of cellulose, hemi-cellulose, and lignin. The suitable natural fibers extraction represents a significant test happening during the processing of plant fibers. The most common methods to separate the plant fibers were dew retting and water retting processes. Depending on the fiber category, the methods need nearly 15 to 30 days for the removal of waxes, pectin substance, hemicellulose and lignin. Alternative methods just like mechanical extraction and chemical treatments have been introduced to reduce long processing time. In retting process, the existence of the bacteria and moisture in the plants allows to break down large parts from cellular tissues and its adhesive substances that surround the fibers, enabling the separation of individual fibers from the plant. The reaction time must be carefully evaluated when using dew or water retting because excessive retting can cause difficulties for the separation of individual fibers or may weaken the fiber strength.
On the other hand, the mechanical extraction process of fibers can produce high-quality fibers with shorter retting time, however in respect to dew or water retting process the technique is more expensive.
Retting is widely used extraction methods of fibers from the plant parts. It is a process of controlled degradation of the plant to allow the fiber to be separated from the woody or non woody core and thereby improving the ease of extraction of the fibers through biological activity of microorganism, bacteria or fungi from the environment to degrade the pectic polysaccharides from the bon fiber tissue and, thereby, separate the fiber bundles. The fiber separation and extraction process has a major impact on fibre yield and final fibre quality. It influences the structure, chemical composition and properties of the fibres. Most scholars divide retting procedures as biological, mechanical, chemical and physical fibre separation process as shown Figure 1.
Biological retting may be either natural or artificial retting. Natural retting comprises dew or field retting and cold water retting. Dew or field retting is commonly applied retting process with appropriate moisture and temperature ranges. Then, the crops should remain on the fields until the microorganisms have separated the fibres from the cortex and xylem then the stalk is dried and baled.
Moreover, Cold water retting by using anaerobic bacteria that breakdown the pectin of plant straw bundles submerged in huge water tanks, ponds, hamlets or rivers and vats. The process takes between 7 and 14 days and depends on the water type, temperature of the retting water and any bacterial inoculum. Even though the process produces high quality fibres, environmental pollution is high due to unacceptable organic fermentation waste waters. Artificial retting involves warm-water or canal retting and produces homogeneous and clean fibres of high quality in 3-5 days. Plant bundles are soaked in warm water tanks. After sufficient retting, the bast fibres are separated from the woody parts. The sheaves or hurds are loosened and extracted from the raw fibres in a breaking or scotching process.
Mechanical or green retting is much simpler and more cost-effective alternative to separate the bast fibre from the plant straw. The raw material for this procedure is either field dried or slightly retted plant straw. The bast fibers are separated from the woody part by mechanical means.
Weather-dependent variations of fiber quality are eliminated. However, the produced green fibers are much coarser and less fine as compared to dew or water retted fibers (Thomas et al., 2011).
Physical retting includes ultrasound and steam explosion method. In ultrasound retting, the stems obtained after the harvest are broken and washed. Slightly crushed stems are immersed in hot water bath that contains small amounts of alkali and surfactants and then exposed to high-intense ultrasound. This continuous process separates the hurds from the fibre. The steam explosion method represents another suitable alternative to the traditional field-retting procedure. Under

Experimental design
Response surface methodology by central composite design (CCD) employing the multivariate approach was used to design the experiment as well as to do the analysis of the results. Because it enables the development of concept using fewer experiments, without wastage of a large amount of time and resource the experimental number of CCD is as per 2 + 2 + where Cp is the replicate number of centre points and k is the factor number. It is more advantageous to decide the ideal condition of the experimental parameters (Bezerra et al., 2008, Gunst, 1996. It leads to the construction of reliable response surfaces that are characterized by high adherence to the experimental data describing the reality being studied (Myers and Montgomery, 1995). Each run in the course of subsequent experimental design was triplicate and the average values were used.
In order to establish better fiber extraction, DOE was applied with a pre-determined set of factors.
Following completion of the treatment according to the developed model design, CCD optimized the obtained significant variables on the efficiency of extraction procedure.

Preparation
CDA stalks were collected and treated using different extraction techniques. The mature CDA stems were stratified and individualized into thinner and flat strips. Then each stem was separated and extracted with mechanical, cold water, and Hot water extraction mechanisms (Nag arajaGanesh, 2016). All samples were striped manually with mechanical action to speed up the extraction time of the bast and core parts of the non-woody stem. All the samples were kept at ambient conditions for a minimum of 3 weeks before the extraction process. The whole extraction process was carried out by combining mechanical and retting techniques followed by stripping, washing, squeezing and sun drying.

Cold water extraction method
The non-woody stems were cut into 5 cm and placed into 20 plastic beakers in cold water at room temperature in aerobic environment with different NaOH concentration and time. The nonwoody stems underwent soaking in water for a minimum of 15 days and a maximum of 40 days to undergo microbial and chemical degradation through retting.
Thereafter, the stalks were dried in natural sunlight to remove moisture content after completion of the retting operation. Then the extracted fibers were set in a controlled laboratory environment for 24hrs before characterization (Indran, 2015).

Hot water extraction method
Known weight of CDA plant samples were treated in NaOH solution with different concentrations.
For the optimization process the following combinations were used; MLR (6-17), NaOH concentration, (1.7-5 %), time (1.5-4 hr.), and temperature (30-60 0 C). After extraction, the extracted fiber was squeezed and dried using oven drying. Then the extracted fiber was stored in sealed plastic bags, in a controlled laboratory environment for further characterization.

Statistical analysis
The data has statistically evaluated using DOE software, Version 11. Analysis of Variance

RESULTS AND DISCUSSION
It is worth mentioning here that unlike any other bast fibers where the fiber extracted only from the outer layer of the plant, the whole non-woody stem of CDA plant was transformed into fiber.
As it is clearly seen in the following sections all the response variables were dependent on the extraction parameters.

Analysis of Variance for Yield
As shown in the ANOVA Table 4, the Model was significant with F-value of 5.75; P-value of 0.0058, which was less than 0.0500; difference between Predicted R-squared and Adjusted Rsquared values was -0.7181 which was less than 0.2 and signal-to-noise ratio value of 8.3726. All those values proved that the model was fitting the data and can reliably be used to interpolation of the factor space, navigate the design space, and entailed that the model has a strong enough signal to be used for optimization. In this case; time, the combination effect of time and NaOH concentration and quadratic value of concentration were significant model terms on the fiber yield.

Effect of NaOH and time on yield
As shown in (Figure 4 a), he linear effect of changing the level of NaOH concentration has a quadratic relationship up to a maximum yield percentage of 51.25 % at the concentration level of 5%. Beyond this range the yield has decreased in quadratic function as NaOH concentration has increased. The reason was due to the quadratic effect of the chemical that increased the degradation rate of the fiber facilitated by time increments.

Interaction effect of NaOH and time on yield
The interaction effect of time and NaOH concentration on fiber yield showed a quadratic effect up to a certain level.

Analysis of Variance for strength
As shown from the ANOVA There was a 54.22% chance that a "Lack of fit F-value" this large was occured due to noise. Nonsignificant lack of fit was worthy need the model to fit.

Effect of NaOH, Time and MLR on strength
From the one factor analysis, NaOH concentration has quadratic effect followed by linear relationship (Figure 6 a).That was because as NaOH concentration increased, the strength increased before degradation point. The reason was that NaOH removed most of the impurities like lignin, pectin and other waste materials that increased the cellulose surface energy to resist applied force on the fibre.  On the contrary, as the duration of extraction increased, the strength increased to a certain level (up to 27 days, but beyond this range strength of the fibre decreased dramatically due to the microbial effect of feeding on the fibre has increased (Figure 6 b). MLR value has a linear relation with strength of fiber (Figure 6 c).

Interaction effect of factors on the fiber strength
For the extraction process with three control variables, the interaction terms significantly affect the strength of the fibre were NaOH concentration and MLR value on strength. The interaction effect of NaOH and MLR was direct relation effect that as NaOH concentration and MLR value increased, the strength of the fibre increased linearly (Figure 7). for both responses. The optimal solutions for the process was developed after considering all of the criteria applied to find the optimal settings and look through all the given solutions to see which ones best meet the specified criteria. The optimal solution has a maximized desirability value of 0.861 with the factor settings in the highest desirability scores, which indicate there is an island of acceptable outcomes. Therefore, the model is optimal process with 3.8 % NaOH concentration and   Table 6 showed that the model F-value of 3.13 implied that the model was significant. There was only a 1.80% chance that the F-value large occurred due to noise levels. Similarly, P-values less than 0.0500 indicated model terms A, D, CD, C², D² were significant model terms and the lack of fit F-value of 0.75 suggested the lack of fit was not significant relative to the pure error. There was only 67.51% chance that a "Lack of Fit F-value" this large occurrence due to noise since nonsignificant lack of fit model was good for the model to fit the expected criteria.

Analysis of Variance for Yield
From the fit statistics analysis, negative predicted R² inferred that the overall mean of the model was a better predictor of the response variables and adequate precision ratio of 7.063 indicated an adequate signal so that the model can be used to navigate the design space as well.

Single Factor Effect Analysis on Yield percentage
The effect of one factor on percentage yield for hot extraction method is shown in Figure 8. NaOH concentration and temperature of extraction have inverse relationship with fiber yield this may be due to the fact that both NaOH and temperature contribute for the complete removal of all the impurities in the fiber, finally reduce the field fiber yield. that there was a 6.28% chance that a lack of fit F-value large occurs due to noise. Furthermore, from the fit statistics, the difference between predicted R² Adjusted R² was less than 0.2 that designated an adequate signal to navigate the design space as well.

Interaction effect analysis of strength in HWEF
The interaction of NaOH concentration and time has a negative linear effect on the strength of the fiber. From Figure 11, it can be concluded that as the concentration increased the tensile strength of the extracted fiber was lowered. This was due to the fact that as time and temperature increases, the degradation rate of the fiber was increased; this in turn reduced the strength of the fiber dramatically. On the other hand, the interaction effect of NaOH and MLR was inversely related effect that as NaOH concentration and MLR value increased, the strength of the fiber decreased linearly. Even though MLR value has positive impact on strength of the fiber, the NaOH concentration affected this scenario and their interactions reduced the strength of the fiber. Figure 11: Interaction effect graph of factors for strength in HWE Generally, from the design evaluation, ANOVA statistics, fit summary and diagnostics graphs, the models provided a good estimate of the true response surface. The extraction process was optimized using design expert software. Since the goals of optimization was to maximize economic benefit by minimizing processing cost, the process variables (concentration, MLR, time and temperature) need to be set within the range and the two response variables, yield and tensile strength were set to maximum levels. Therefore, the model was optimal process with 1.7% NaOH concentration and 6:1 MLR value treated at 30℃ for 90 minutes with a maximal yield of 59.6% fiber having an optimized tensile strength of 247.68 cN/Tex. From the two extraction techniques, the hot water extraction was found the better optimized process in both strength (247.68 cN/Tex) and yield (59.6%) than that of cold-water extraction.

Conclusions
The need for recyclable, renewable and sustainable materials has brought about the amplified consumption of natural fibers for various applications. This study was mainly focused on the optimization of extraction techniques of the lignocellulosic fiber derived from Cyperus Dichrostachus A.Rich plant. On the progress of the study, the new natural lignocellulosic fiber was successfully extracted using the well optimized extraction techniques and successfully demonstrated to be an alternative source for producing the fiber. The fiber was extracted with cold The elimination of lignin, hemicellulose and pectic substances from the fiber strands on hot water extraction was proved by repeated tests. The tensile property of the fiber was increased for hot extraction due to improved fiber structure at for 1.7% NaOH treatment that gave optimized strength and yield.