Low-cost ternary composite photocatalysts consisting of TiO 2 , kaolinite and cement for an efficient organic waste decontamination in water

: The present study demonstrates the fabrication of heterogeneous ternary composite photocatalyst consisting of TiO 2 , kaolinite and cement (TKCe), which is essential to overcome the practical barriers that are inherent to currently available photocatalysts. TKCe is prepared via a cost-effective method, which involved the mechanical compression and thermal activation as a major fabrication steps. Clay-cement ratio primarily determines TKCe mechanical strength and photocatalytic efficiency where TKCe with the optimum clay-cement ratio, which is 1:1 results in uniform matrix with fewer surface defects. The composites that have clay-cement ratio below or above the optimum ratio account for comparatively low mechanical strength and photocatalytic activity due to inhomogeneous surface with more defects, including particle agglomeration and cracks. The TKCe mechanical strength is mainly from clay-TiO 2 interactions and TiO 2 -cement interactions. TiO 2 -cement interactions result in CaTiO 3 formation, which significantly increases matrix interactions; however, the maximum composite performance is observed at the optimum titanate level; anything above or below this level deteriorates composite performance. Over 90% degradation rates are characteristic to all TKCe, which follow pseudo first order kinetics in methylene blue decontamination. The highest rate constant is observed with TKCe 1-1, which is 1.57 h −1 and being the highest among all the binary composite photocatalyst that were fabricated previously. The TKCe 1-1 accounts for the highest mechanical strength, which is 6.97 MPa, while the lowest is observed with TKCe 3-1, indicating that clay-cement ratio has direct relation to composite strength. TKCe is a potential photocatalyst, which can be obtained in variable sizes and shapes, complying with real industrial wastewater treatment requirements.


Introduction
Rapid industrialization, agrochemical consumption, and a limited disposal space have all contributed to the accumulation of organic waste in water bodies, which is responsible for significant environmental pollution [1].Traditional wastewater treatment methods (alkaline hydrolysis) are less viable due to drawbacks such as high alkaline consumption, low treatment efficiency, and environmental pollution caused primarily by alkaline disposal [1].The photo-catalyzed advanced oxidation method outperforms conventional treatment methods for organic waste decontamination in water.Photocatalytic degradation is a well-known advanced oxidation process due to its high efficiency and environmental friendliness when compared to other advanced oxidation processes, including Photo-Fenton technique that require additional reagents [2].TiO2 is a well-known semiconductor photocatalyst that can decontaminate a wide range of organics and microorganisms while producing inorganic species that are naturally harmless.This is mainly achieved via an advance oxidation where the organic waste decontamination initiated by electron-hole pair generation under sunlight/UV irradiation that is often used to mineralize a variety of organic pollutants in wastewater.Because of its high photocatalytic activity/stability, chemical/biological inertness, and low cost, TiO2 has been widely used.
Photocatalysts can be utilized as a powder, membrane (immobilized on the surface of a suitable substrate), or composite material.TiO2 powder is less effective as a photocatalyst alone because of its small specific surface area, low adsorption ability, photocatalyst agglomeration, and post-separation issues [1].A supportive substrate that has a large surface area and a high adsorption capacity should be used to immobilize TiO2 powder that is an essential step overcomes these limitations.Photocatalyst immobilization can be accomplished on a variety of substrates.Powder/pellet, soft/thin, and rigid substrates are the three major classes that have often used [3].Activated carbon, clay, and volcanic ash are the best powder/pellet substrates for immobilizing photocatalysts.The soft/thin substrates fall within a broad range, including alumina, polyvinylidene difluoride, glass filter, cellulose fibers, and sponge [4][5][6][7].TiO2 can be immobilized on a substrate using one of two methods, including binders' incorporation or physically anchoring TiO2 particles on a substrate [1].Poor TiO2 immobilization is caused by the use of organic/inorganic binders, including polyester resin, polyethylene, polypropylene, polyethylene glycol, and silicon adhesive [8][9][10].Because the binders are typically organic in nature, they are highly susceptible to self-degradation (by TiO2) when exposed to sunlight/UV light.TiO2 particles, on the other hand, can submerge and agglomerate within the binder, resulting in decreased photocatalytic activity.The coating preparation is also imperfect and complex, resulting in a number of difficulties to control the uniformity and durability.
Existing techniques are limited to laboratory scale or prototypes, and their commercial applications are imperfect.Due to the low stability/durability of the photocatalysts and engineering constraints that are related to reactor design fail to meet industrial waste disposal standards.From an industrial standpoint, low-cost, longlasting photocatalysts that can be easily integrated into commercial wastewater treatment units are essential.Furthermore, having a readily available photocatalyst that can be easily synthesized on a large scale is more important.Authors of the present study recently developed a novel composite preparation method based on mechanical compression and heat treatment, resulting in a stable binder-free graphite and clay composite electrode [21][22][23][24][25].Following a similar technique, authors recently developed an efficient binary photocatalysts, which are composed by raw materials, including TiO2 and clay (kaolinite/MMT), resulting in improved photocatalytic activity and mechanical strength [26,27].However, authors also found that ternary composites that are related to graphite-clay composite electrodes outperform the binary electrodes, revealing that such ternary composites results in matrix enhancements [23,24].Based on a similar hypothesis, the current study is demonstrated the fabrication of ternary TiO2-clay-cement composite photocatalyst (TKCe) for the first time.The TKCP offers numerous advantages, including high photocatalytic activity, mechanical stability, mouldability, chemical-free surface regeneration, and a long shelf life, resulting in an effective photocatalyst that can bridge the gap between lab scale and commercial products.

TKCe block fabrication
To prepare composite suspensions, a fixed amount of TiO2 (80%) was mixed in distilled water with various clay and cement (total 20%) ratios and then continuously stirred at 1000 rpm using an overhead agitator (IKA, Germany) for 3 h.TKCe 1-3, TKCe 1-1, and TKCe 3-1 were prepared in 25 g by combining kaolinite and cement in the following ratios: 1:3, 1:1, and 3:1.TKCe blocks with dimensions of 4 cm × 4 cm × 0.8 cm were fabricated by applying a 125,000 N vertical ram force for 30 min to a partially dried composite material that was uniformly packed inside a specially designed steel mould.TKCe blocks were then calcined for 2 h at 600 ℃ in a hightemperature furnace (Nebertherm), resulting in a TiO2-kaolinite-cement heterogeneous photocatalyst (Figure 1).The TKCe photocatalytic activity was determined using modified blocks with an untreated top surface.To accomplish this, the TKCe blocks' side and bottom surfaces were uniformly painted, except the top surface, which serves as the active exterior, facilitating photocatalytic disintegration.

TKCe block characterization
To characterize the TKCe blocks and raw materials, an X-ray diffractometer (Rigaku Ultima IV, Japan) equipped with a copper target X-ray generator (CuK1-0.154056nm), a secondary beam curved graphite monochromator, and a D/tex Ultra detector was used.An X-ray beam generated under standard tube conditions, including a 40 kV tube voltage and a current of 30 mA, was used to analyze the powdered samples.The samples were scanned between 15° and 80° at 2° min −1 to obtain diffractograms.The X-ray beam geometry was carefully optimized, with the divergence, scattering, and receiving slits all fine-tuned by 2/3°, 2/3°, and 0.45 mm, respectively.The Rietveld refinement on XRD profiles was performed using an advanced WPPF (whole powder pattern fitting) component that integrated with the PDXL X-ray powder diffraction software.The refined diffractograms were analyzed with the PDXL integrated X-ray powder diffraction software, which was linked to the ICDD (International Centre for Diffraction Data) database.The composition analysis was achieved via Relative Intensity Ratio (RIR) module that is available with powder diffraction software.The crystallite size estimation related to both anatase and rutile was carried out accurately by analyzing refined diffractograms using the Halder-Wagner model available with PDXL software.
The flexural strength was calculated by substituting the force at rupture of a TKCe strip that was measured using universal testing machine (Testometric, UK).To accomplish this, the TKCe strip was carefully placed horizontally on the Testometric universal testing machine's supporting stage, and the force at the fracture point was measured upon collision with a load that vertically lowered at a rate of 2 mm min −1 .
The TKCe series was examined using a scanning electron microscope (ZEISS EVO LS15, Germany), which produced well-resolved images at a constant accelerating voltage of 20 kV.The FT-IR spectra were collected in an attenuation total reflection module (ATR) with a diamond puck (sample compartment) using a Bruker Tensor 27 spectrometer (Germany).The samples were scanned between 600 and 4000 cm −1 at a resolution of 4 cm −1 , yielding a transmittance spectrum from which the vibration frequencies corresponding to IR bands were obtained.TGA/DSC analysis (TA instruments SDTQ600, USA) was used to determine the thermal profile and stability of kaolinite.

TKCe photocatalytic activity determination
Methylene blue degradation in the presence of TKCe was measured using a UV-Visible spectrophotometer (UV-1800 Shimadzu, Japan, at λmax = 664 nm).Each TKCe block was placed in a crystallization flask (150 mL) followed by adding 100 mL of methylene blue solution (1.56 × 10 −5 mol dm −3 ).The reaction vessels were exposed to sunlight for 2.5 h, with absorbance measurements taken at every thirty minutes (Figure 2).The dye concentration (CMB) after each consecutive irradiation was determined carefully using a calibration plot that was preliminary constructed with known methylene blue concentrations.The calibration plot was constructed using the UVProbe software, which is interfaced with the UV-Vis spectrophotometer.The irradiated methylene blue concentration was determined directly from the previously installed calibration plot.The entire experiment was conducted in direct sunlight, with an average irradiation of 400 W m −2 (intensity).After determining the methylene blue concentration in relation to the control sample, the percentage degradation (DR) and the pseudo first-order rate constant (k) were calculated using the following relationships [29].

Results and discussion
According to previous studies, TiO2 amount that can effectively incorporate into a binary TiO2-clay based composite photocatalyst is found to be 60%, greater than which the composite stability is drastically reduced, causing multiple surface cracks [26].In the present study, TiO2 percentage that can incorporate into the composite photocatalysts is greater than the previously fabricated binary composite photocatalyst.This is mainly due to cement incorporation as an additional mineral phase, which results in a high TiO2 loading capacity without deteriorating the composite mechanical strength.The clay itself can only increase the TiO2 loading capacity up to some extent, but the clay-cement combination makes the composite architectural framework quite stronger, which results in a stable ternary composite photocatalysts.The high TiO2 loading capacity is an advantage that makes TiO2 surface concentration very high, resulting in a high photocatalytic activity.This is a good indication for an advancement of solid state composite engineering, which highlights the incorporation of minerals together, including clay and cement that can significantly improve the photocatalysts properties and performance.
The clay firing is a major step that led to a strong photocatalyst matrix, which is mainly resulted from the dehydroxylation, integrating the clay mineral with other composite components.Among the many clay types available, kaolinite was chosen in the current study due to its low cost, high abundance, and platy sheet-like structure, which allow easy processing of the material at high compressibility [26].Figure 3 exhibits TGA/DTA thermogram, which reveals that kaolinite is typically undergoing dehydroxylation at 500 ℃, resulting in a rigid clay matrix.Therefore, the firing temperature was set at 600 ℃ to ensure the complete dehydroxylation.It also reveals that the spinal crystallization take place at 1000 ℃ followed by mullite and crystobalite formation, which is typically occurred above 1100 ℃.The TKCe photocatalytic activity and the mechanical strength both are important factors that determine the industrial level feasibility.TKCe 1-1 account for the highest photocatalytic activity and mechanical strength, revealing that 1:1 kaolinite to cement ratio resulted in an effective composite matrix (Table 1).Over 98% degradation rate (DR) is observed with TKCe 1-1, which is the highest among all binary composite photocatalysts that are fabricated previously and raw TiO2 [26,27].The authors' previous study observed a very low DR (72.5%) and pseudo first order rate constant (k = 0.28 h −1 ) related to raw TiO2 when it used in powder form that is mainly due to the ultra fine particle nature of TiO2, which results in a colloidal suspension where the tiny particles are dispersed throughout the entire solution [26].This is caused poor sunlight penetration and scattering through the suspension, which results in an ineffective sample irradiation [26].TKCe 1-1 is also accounted for the highest pseudo first-order rate constant (k), which is higher than binary composites and many photocatalysts test against methylene blue, including TiO2 nanotrees (0.346 h −1 ), TiO2 nanobelts (0.026 h −1 ), multilayer TiO2 coating on HDPE (0.27-0.43 h −1 ) and GO-ZnO-Cu nanocomposite (0.246 h −1 ) [26,[30][31][32] (see Table 1 and Figure 4).The plots (C vs. time and 1/C vs. time) both are accounted for a nonlinear relationship, which confirms the deviation from the zero and the second-order reaction kinetics (Figure 4).TKCe 1-3 and TKCe 3-1 both are accounted for a higher %degradation and k compared to previously develop binary TiO2-kaolinite (TKCP) and TiO2-kaolinite-MMT composite (TKMCP) photocatalysts.These binary composites have shown less than 95% degradation rate in comparison to TKCe, which exhibits a DR > 98% (Table 1).TKCe 1-1 rate constant, which is 1.57h −1 , is quite similar to that of TKMCP (1.55 h −1 ) and is greater than that of TKCP (0.58 h −1 ) [26,27].The mechanical strength of TKCe follows a similar trend as photocatalytic activity, with the highest observed with TKCe 1-1 (6.97 MPa), implying that the optimal cement percentage is critical for a better composite matrix (Table 1).The much lower or higher cement percentages results in a comparatively deteriorated properties and performance of TKCe.In that sense, the highest DR, σf, and k were observed in TKCe 1-1, which is considered the composite with optimum kaolinite to cement ratio; the composites that deviate from the optimum ratio account for comparatively low DR, σf, and k (see Table 1).Among the rest of the TKCe composites, the composite with more cement accounts for a stronger matrix than the one with the lowest cement fraction that is TKCe 3-1.In contrast, the composite with high clay fraction results in a better photocatalytic activity than the one with low clay fraction, which is TKCe 1-3 (Table 1).TKCe 1-1 mechanical strength is greater than that of binary composites, including TKCP (3.55 MPa) and TKMCP (5.83 MPa) that were fabricated previously [26,27].Therefore, an optimum clay-cement combination simultaneously results in high photocatalytic activity and mechanical strength, which is observed in TKCe 1-1, revealing that proper raw material combinations can make significant impact on composite properties.
The improved photocatalytic activity and mechanical strength related to TKCe 1-1 can be explained considering four factors, including anatase to rutile ratio, crystallite size, calcium titanate percentage and morphology.The anatase to rutile ratio in each composite is determined using an X-ray diffraction analysis and results are given in Table 2.The authors of the current article revealed that the same TiO2 powder underwent a measurable phase transition at low temperatures, resulting in a composition change of approximately 25% at 650 ℃ [33].Such phase transition is prevented in binary composites that are fabricated using clay.This is because clay eventually acts as a phase transformation barrier and predominantly undergoes dehydroxylation, preventing anatase to rutile transformation [26,27].In the present study, kaolinite also acts as a barrier for anatase to rutile conversion, preventing the phase transformation, which results in a marginal change in rutile percentage (Table 2).Kaolinite not only serves as a phase transition barrier, but it also provides an architectural framework for strengthening the composite matrix.TKCe composites are negative for characteristic kaolinite XRD peaks, indicating that dehydroxylation occurred completely, resulting in metakaolinite, which is amorphous in nature (please see Figures 5 and 6).The FT-IR spectra related to TKCe provide clear evidence for the amorphization of kaolinite, which is confirmed by the absence of characteristic kaolinite IR bands between 1250-600 cm −1 (in plane Si-O stretching vibration at 1114 & 1007 cm −1 , OH vibration of inner and outer Al-OH bonds at 912 cm −1 , Si-O-Al stretching vibration at 788 and 748 cm −1 ) and an emergence of amorphous SiO2 peak at 1070 cm −1 (Figure 7).This anti-symmetric Si-O stretching band is unique to metakaolinite, and the absence of bands in composites at 3689 and 3619 cm −1 , which correspond to the stretching vibration of hydroxyl, ensures complete dehydroxylation [34].However, the situation is somewhat different when incorporating cement as a ternary phase that consumes anatase to produce calcium titanate (CaTiO3) instead of undergoing phase transformation, resulting in a considerable reduction in anatase percentage (Table 2).This is clearly reflected by anatase and rutile percentages that are observed in composites and raw TiO2, exhibiting a significant reduction in anatase percentage unlike rutile, which is quite similar in magnitude (Table 2).The calcium titanate formation is typically occurred at high temperature, which is above 900 ℃ [35].In the present study CaTiO3 is emerged at 600 ℃, revealing that such formation is likely induced by highly compressed matrix, which is responsible for low temperature titanate formation.This is a good indication for mechanical activation that is mainly resulted from the highly compressed matrix, which triggers the thermal conversion of minerals within the composite even at low to moderate temperatures.CaTiO3 formation begins with the thermal decomposition of calcite, which resulted in CaO (calcite from cement, see Figure 5).However, calcite decomposition is a hightemperature process that typically occurs above 700 ℃ [36].
In the present study, the mechanical compression is implemented as a fabrication technique that leads to highly compressed material matrix, which is eventually experienced very high matrix stress.The composite heating also accounts for further increase in matrix stress where the composite matrix tries to regain the stability via either thermal decomposition or matrix distortion.The thermal decomposition is more effective than the matrix deformation where the matrix stability is likely achieved via material loss, resulting in a low matrix stress [36,37].This explains why calcite is decomposed even at temperature that is well below the typical decomposition temperature.The CO2 removal during calcite decomposition is likely reduced the matrix stress by increasing the internal space, which is mainly caused by material loss [36].Therefore, unlike non-compressed materials, the materials that are under high compression strain can easily undergo thermal conversions even at low to moderate temperatures.
The reaction between CaO and TiO2 produced orthorhombic CaTiO3, which is the stable phase below 1200 ℃; this is more pronounced in TKCe contains more cement (Figure 6 and Table 2).During CaTiO3 formation, the reaction is most likely propagated in the following sequence [35,36].
600 ℃(2 ℎ) The TKCe X-ray diffractograms provide clear evidence for titanate formation and the amorphization of certain cement phases that are available at room temperature.The absence of characteristic cement phases in TKCe, including calcium silicate and aluminates is a better indication for cement amorphization, which is also reflected in TKCe FT-IR spectra (Figure 7).Raw cement exhibits the characteristic vibrational modes at 871, 1083, and 1425 cm −1 , which are corresponded to CO3 2− stretching (outof-plane), Si-O-Si stretching, and CO3 2− stretching (asymmetric) modes, respectively (Figure 7) [38].These modes are mainly caused by primary constituents in cement, including CaCO3 and calcium silicate (Figure 6).Low intense broad titanate FT-IR vibration band can be seen in all composites (1455 cm −1 ), but it is more pronounced in TKCe 1-3 that has the highest titanate percentage (Figure 7) [39].The most distinctive cement IR bands, which correspond to calcite CO3 2− vibrations, and CaTiO3 fingerprint bands are masked by a broad Ti-O-Ti stretching vibration band that typically appears between 900 and 600 cm −1 (see Figure 7) [26,27].
In TiO2-clay binary composites that are recently developed, the dehydroxylation typically results in Ti-O-Si and Al-O-Ti bond formation that ensures strong composite matrix [26,27].However, in the present study CaTiO3 directly involved in material architectural framework, increasing the mechanical strength in addition to Ti-O-Si and Al-O-Ti formation that is reflected by TKCe very high flexural strength (Tables 1 and  2).However, CaTiO3 in excess can negatively affect the matrix uniformity, which results in the lowest flexural strength and photocatalytic activity that are clearly noticeable in TKCe 1-3 (Tables 1 and 2).This indicates that an optimum CaTiO3 level is important to have uniform composite matrix with improved properties.The numerous studies have revealed that anatase itself is a relatively poor photocatalyst but anatase and rutile mixtures are better photocatalysts with a wide range of applications [40].The optimum titanate level is also accounted for proper anatase to rutile ratio that is quite essential to obtain an efficient photocatalyst with a high activity, which is clearly reflected in TKCe 1-1 (Table 1).
Anatase crystallite size and photocatalytic activity has a direct relation that is well noticeable in TKCe 1-3, which has smallest anatase crystallites, resulting in a lowest catalytic activity.The more cement in TKCe can produce excess CaTiO3, during the production of which anatase crystallites are greatly consumed upon the reaction with CaO that likely damage the crystallites, resulting in small anatase crystallites.A small anatase crystallite size is a strong indication of the matrix defects that are typically generated during the titanate formation.The titanate formation via anatase incorporation is confirmed by a significant decrease in anatase size and a marginal change in rutile crystallite size, indicating that rutile is less important in titanate formation, most likely due to structural disparity and low abundance (see Table 2).
However, up to certain level, the titanate formation is positively affected on TKCe properties and performance, resulting in an improved mechanical strength and catalytic activity.This is in better agreement with the high DR observed with TKCe 1-1, which has the largest anatase crystallites (Table 2).However, this is somewhat opposite when the titanate percentage increased above the optimum level where the excess CaTiO3 is likely damaged the composite matrix, destabilizing anatase lattice, which results in small crystallites.
The TKCe composition-matrix correlations are clearly reflected in SEM micrographs, which reveal the structural alterations that occurred under mechanical and heat treatment.The SEM images reveal that a uniform composite surface is more pronounced in TKCe 1-1 compared to both TKCe 1-3 and TKCe 3-1, which have somewhat less uniform surfaces.In contrast to binary TiO2-clay composite photocatalysts, cement incorporation induces raw material amalgamation, resulting in small spherical composite particles that are packed together, resulting in a compressed composite matrix (Figure 8).The composite particle nature, including shape and size are important in determining the composite's compressibility under hydraulic pressing.However, it is obvious that the size of such composite particles is determined by their composition, particularly the ratio of kaolinite to cement.
The TKCe 1-1 SEM micrograph clearly exhibits fewer surface defects and a wellorganized, uniform composite matrix, which explains the TKCe 1-1 improved mechanical strength and photocatalytic activity.In contrast to TKCe 1-1, both TKCe 1-3 and TKCe 3-1 have partially compressed matrixes with more surface defects, including particle agglomerates and cracks.This explains why mechanical compression and heat treatment are more effective when the optimal matrix composition is used, resulting in a uniform matrix with low surface defects.The optimum composition is important to have composite particles that can undergo effective mechanical compression (high compressibility), resulting in a highly compressed matrix.In contrast, both TKCe 1-3 and TKCe 3-1 resulted in poor compressibility, leaving more surface defects, including particle agglomerates and cracks.Therefore, the deviation from optimum raw material ratios accounted for a less uniform composite matrix with comparatively higher surface defects, which are mostly the particle agglomerations, forming as a result of low compressibility.The latter is accounted for partially compressed composite particles that are still noticeable in both TKCe 1-3 and TKCe 3-1 SEM micrographs.
The TiO2 immobilization technique described here is very useful for large-scale commercial photocatalyst fabrication, with a focus on high-capacity wastewater treatment plants that are powered by renewable sunlight or UV irradiation.The simple chemical-free fabrication process makes commercial-level TKCe production more feasible, requiring minimal supervision and machinery and yielding a high output.TKCe has several advantages, including easy fabrication, low cost, free of hazardous chemicals, high production capacity with minimal machinery/supervision, non-selfdegradability, easy disposal, easy installation in pilot-scale reactors, compatibility with both batch and flow reactors, and environmental, and user-friendliness.

Conclusions
An industrially feasible TiO2-kaolinite-cement composite photocatalyst is prepared using inexpensive raw materials via a straightforward method.Fabrication route is intended to avoid additional reagents; making the process more economical, faster and environmental friendly (green technology).The TKCe can be manufactured in a variety of shapes and sizes to match the reactor dimensions, reducing engineering constraints when upgrading the lab-scale product to pilot-scale reactors.The physical properties of TKCe are primarily determined by the clay-cement ratio where the optimum ratio, which is 1:1 exhibits the highest photocatalytic activity and flexural strength.This is mainly due to uniform TKCe matrix with fewer surface defects, which resulted from high compressibility.Composites with clay-cement ratios below or above the optimum ratio exhibit lower mechanical strength and photocatalytic activity due to an inhomogeneous surface with more defects, such as particle agglomeration and cracks.TKCe mechanical strength is primarily derived from clay-TiO2 interactions and TiO2-cement interactions.TiO2-cement combination results in a CaTiO3, which significantly improves matrix interactions; however, the best composite performance is achieved at the optimal titanate level; anything above or below this level negatively affects composite performance.The TiO2 immobilization technique that described here is very useful for large-scale commercial photocatalyst fabrication, with a focus on high-capacity wastewater treatment plants powered by renewable sunlight or UV irradiation.The simple chemical-free fabrication process enables commercial-scale TKCe production with minimal supervision and machinery, resulting in a high production capacity.

Figure 1 .
Figure 1.TKCe blocks prepared with different kaolinite and cement ratios.

Figure 7 .
Figure 7. FT-IR spectra of Raw materials and composites.

Table 1 .
TKCe flexural strength, DR and pseudo first-order rate constant.