Activator Concentration Research Articles

High quenching concentration of the CaLuAlO4:Er3+ upconversion phosphor with short-range energy migration

Low activator concentration in upconversion phosphors has been a hindrance in improving luminescence performance. Herein, we report an Er3+ doping concentration as high as 30 at. % in the CaLuAlO4 upconversion host. The CaLuAlO4:Er3+ phosphors were prepared by the traditional high-temperature solid-state method. Under the excitation of a 980 nm laser, the optimal concentration of Er3+ approaches 30% according to the total integrated intensity of red and green upconversion luminescence. This quenching concentration is one order of magnitude higher than that in the traditional Er3+ doped upconversion polycrystals. The results obtained from first-principles calculations suggest that there are no in-plane or chain rare-earth ions in the cell. This increases the difficulty of propagating excitation energy to quench centers and is advantageous for high doping concentration. Our work can spark people's interest in the research and application of highly doped upconversion phosphors.

Characterization and fractal analysis of drying shrinkage of metakaolin-based geopolymers under gradually-decreasing humidity

This study investigated the drying shrinkage of metakaolin (MK)-based geopolymers paste under a relative humidity gradient (decreasing step-by-step) with different activator modules, activator concentrations, and liquid-solid ratios. These results were then compared with those of a cement paste with the same strength grade. The mechanisms of various factors affecting the drying shrinkage of MK-based geopolymer were elucidated using MIP and TAM Air techniques. Subsequently, fractal analysis was conducted using the pore structure data obtained through MIP to investigate the correlation between fractal dimension and drying shrinkage. The results showed that the drying shrinkage of MK-based geopolymers was greater than that of a cement paste at the same strength grade. MK-based geopolymers exhibited earlier shrinkage than the cement paste during the reduction in humidity. Moreover, the drying shrinkage of MK-based geopolymers increased with a decrease in activator modulus, and an increase in activator concentration and liquid-solid ratio. In the present study, the fractal dimension of the microcapillary exhibited an excellent relationship with the drying shrinkage at various relative humidities. This indicates that the fractal dimension can be used to evaluate the drying shrinkage performance of MK-based geopolymers.

Experimental study on strength, durability, hydraulic and toxicity characteristics of soil treated with mine tailings based geopolymers for sustainable road subgrade application

This article explores the utilization potential of three distinct mine tailings (MT) viz.; red mud (RM), iron tailings (FeT), and zinc tailings (ZT) as geopolymer binders to stabilize the soil for road subgrade application. The strength and durability of soil treated with various MT-based geopolymers are examined through a succession of unconfined compressive strength (UCS), California bearing ratio (CBR) and alternate wetting-drying tests respectively. Furthermore, permeability tests are also conducted to examine the hydraulic response of soil amended with MT-based geopolymers. Finally, leaching study is performed to examine the geo-environmental implications of various geopolymer specimens. The experimental results reveal that the UCS of untreated soil is increased from 0.39 MPa to 5.24 MPa, 5.13 MPa and 3.78 MPa with the use of RM, FeT, and ZT-based geopolymers respectively. The study further shows a 26-fold, 19-fold, and 15.8-fold increase in the soaked CBR values of soil when it is stabilized with RM, FeT, and ZT-based geopolymers respectively. In contrast to untreated soil, soil stabilized with MT-based geopolymers exhibit excellent weathering resistance to alternate wetting-drying cycles showcasing its exceptional durability under challenging environmental conditions. Irrespective of the MT content, curing environment, and the alkali activator concentrations, soil treated with MT-based geopolymers is found to satisfy both the strength (i.e. UCS = 0.75–1.5 MPa and CBR > 5%) as well as durability criteria (i.e. % loss in mass < 10%) specified by Indian Road Congress for subgrade soil. Moreover, the leaching study shows the concentrations of toxic elements (Zn, Cd, Fe, Pb, Ni etc.) to be within the permissible limits specified by USEPA thereby dispelling any environmental concerns associated with the use of MT-based geopolymers.

Stabilization of an iron ore tailings by-product with perlite waste geopolymer

In the field of engineering, sustainable solutions that can generate lower environmental impacts, either through material replacement or reuse, are increasingly sought after. In Brazil, in the geotechnical area, there is a demand to find solutions to avoid the disposal of tailings sludge destined for structures, following the recent dam ruptures of Fundao in 2015 and Corrego do Feijao in 2019. One of the recent investments is in the treatment of tailings, generating by-products. To improve the mechanical properties of these by-products, geopolymer utilization has been employed. Geopolymers are products resulting from reactions between aluminosilicate precursors and alkaline activators. The objective of this study is to evaluate the unconfined compressive strength of an iron ore tailings by-product stabilized with a geopolymer that utilizes perlite waste as a precursor and sodium hydroxide as an activator through a two-part alkali-activation process. Two molar concentrations of activators, 2M and 5M, and two sample compositions were evaluated: one with 20% geopolymer and 80% iron ore tailings by-product, and another with 30% and 70%. An increase in unconfined compressive strength was observed with higher concentrations of the activator solution and a greater percentage of geopolymer in material stabilization. Thus, it can be stated that the use of geopolymers in by-product stabilization is promising, but finding the optimal dosage and evaluating other variables such as curing time and temperature is necessary.

Carbonization of rice husk for adsorption of phosphate compounds: Influence of temperature and NaOH activator

Rice husk is mostly composed of cellulose, hemicellulose, and lignin that can be converted into carbon to be used as an adsorbent. Phosphate is one of the elements that cause eutrophication, resulting in algae blooming. The purpose of this research is to determine the best carbonization temperature and concentration of NaOH activator. The phosphate compounds studied are Sodium Tripolyphosphate (STPP) as artificial phosphate compounds and phosphate compounds in laundry wastewater. Carbonization of rice husk was done for 1 hour with temperature varied at 400, 425 and 450°C. The carbon activation of rice husk was done for 24 hours with variation of NaOH concentrations of 0.3, 0.5, and 0.7 M. The performance test of 100 mesh activated carbon was performed at a speed of 100 rpm and stirring time of 45 minutes. Activated carbon with the best characteristics was obtained from a carbonization temperature of 450°C and activated by 0.3 M NaOH. The characteristics obtained were 1.90%, 35.82%, 20.04%, 42.25%, 49.4 mg/g for water content, ash content, volatile matters, fixed carbon, methylene blue adsorption, respectively. The best dose was 16 g/L of active carbon with an adsorption efficiency of 75.15% on STPP and 93.7% on laundry wastewater.

Fresh Properties, Strength, and Durability of Fiber-Reinforced Geopolymer and Conventional Concrete: A Review.

Reducing the environmental footprint of the construction industry in general and concrete in particular is essential. The addition of synthetic and natural fibers to concrete mixes at appropriate dosages enhances durability and strength and extends the lifespan of concrete infrastructures. This study reviews the geometric and mechanical properties of selected fibers such as steel, basalt, polypropylene, polyvinyl alcohol, polyethylene, glass, carbon, and natural fibers and their impact on concrete fresh, mechanical, and durability properties when combined in different configurations. The study focuses on the effect of blending fibers with concrete mixes that use alkali-activated binders based on recycled industrial byproducts such as slag and fly ash and thereby contribute to reduction of CO2 contribution through complete or partial replacement of Ordinary Portland cement (OPC). As a result, the effect of binder content, binder composition, alkaline activator concentration, and water-to-binder (w/b) ratio on fresh properties, mechanical strength, and durability of concrete with blended fibers is also evaluated in this study. The properties of fiber-reinforced concrete with alkali-activated binder and conventional OPC binders are compared. Fiber-reinforced concrete with alkali-activated binders that are based on industrial byproducts may represent sustainable alternatives to conventional concrete and offers competitive fresh and mechanical properties when fiber properties, fiber content, w/b ratio, binder type, and dosage are carefully considered in concrete mix design.

Effect of Chemical Activator Concentration on the Quality of Activated Carbon from Polypropylene Plastic

Effect of Chemical Activator Concentration on the Quality of Activated Carbon from Polypropylene Plastic

Optimization and Characterization of Adsorbent from Palm Kernel Shell Waste Using H3PO4 Activator

&lt;p class="E-JOURNALHeading1"&gt;Palm kernel shell is solid waste produced from the processing of crude palm oil (CPO). In this context, phosphoric acid (H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;) serves as an essential activator for producing an adsorbent with maximum micropore under operating conditions at a temperature of &amp;lt;450&lt;sup&gt;o&lt;/sup&gt;C. Therefore, this study aimed to determine the optimal adsorbent condition of the palm kernel shell using H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;activator. The production process was optimized using Response Surface Methodology (RSM) and Central Composite Design (CCD) methods with activator concentration variations of 4%, 5%, and 6%, at activation times of 23 hours, 24 hours, and 25 hours, respectively. The quality of the adsorbent produced fulfilled SNI standard 06-3730-1995, characterized by water content of 1.001%, ash content of 5.767%, missing substance level of 18.932%, and fixed carbon content of 75.301%. Furthermore, this work effectively optimized the RSM and CCD adsorbent production process, achieving 4.785% variation in activator concentration and 24.679 hours activation time.&lt;/p&gt;

Setting time, sulfuric acid resistance, and strength development of alkali-activated mortar with slag & fly ash binders

This study evaluated the effect of initial molar ratios SiO2/Al2O3 and (CaO + SiO2)/Al2O3, on the setting time of mortar with alkali-activated Ground Granulated Blast Furnace Slag (GBS) and fly ash (FA) binders. The study also evaluated the chemical resistance of alkali-activated mortar and the effect of NaOH alkaline activator on resistance to sulfuric acid in particular. Mortar samples were cured at 22 ± 2 °C and 70% relative humidity (RH). Three GBS/FA binder combinations were evaluated: 1:1, 3:1, and 1:0 (100% GBS). Activation was done using a combination of sodium hydroxide, with concentrations from 10 mol/L to 16 mol/L, combined with sodium silicate solution. Chemical resistance was evaluated by immersing mortar samples in sulfuric acid. Geopolymer mortar samples cured in an open system exhibited an increase in compressive strength from the age of 1 day–28 days. However, at the age of 90 days, all air-cured mortar samples, irrespective of activator concentration, decreased in strength. Similar mortar specimens immersed in sulfuric acid 24 h after casting exhibited a continuous increase in strength until the age of 90 days. Water evaporates from an open system which may cause partial precipitation of dissolved silicates rather than the formation of geopolymer products. The medium containing the sulfuric acid provided a closed system simulating a physical barrier against evaporation, and making dissolved silicates available to participate in the formation of geopolymerization products. Setting time was found to have a stronger correlation with the initial molar ratio of (CaO + SiO2)/Al2O3, than the molar ratio SiO2/Al2O3. Several mathematical models for predicting splitting tensile strength were developed and the goodness-of-fit to test data was evaluated using the integral absolute error (IAE).

Role of angiotensin II and neuroendocrine factors in immunological regulation in patients with coronary heart disease: prospective cross-sectional study

BACKGROUND: Among chronic noncommunicable diseases, cardiovascular diseases, particularly coronary heart disease (CHD), are the leading cause of death. The rennin-angiotensin-aldosterone system plays an important role in CHD development and progression; however, its role in the regulation of immunoneuroendocrine interactions requires further analysis.&#x0D; OBJECTIVE: To study the relationship between angiotensin II (AT II) and molecular regulators of the activity of whole blood mononuclear cells (MNCs) in patients with angina pectoris.&#x0D; MATERIALS AND METHODS: This cross-sectional study enrolled 65 patients with exertional angina aged 45–67 years, including 19 apparently healthy individuals. The levels of interleukins (ILs), transforming growth factor-β1 (TGF-β1), prostaglandin E2 (PG E2), serotonin, thyroid-stimulating hormone (TSH), and AT II in the blood serum were determined. In MNCs, the concentrations of protein kinases FAK, JNK, p38, and ERK, signal transducers, and activators of transcription (STAT 3, 5A, and 6) were determined.&#x0D; RESULTS: In patients with coronary artery disease, the production of TGF-β1 increased by 7.2% (p=0.00001), AT II by 136.9% (p=0.0001), serotonin by 129.0% (p=0.00001), IL-18 by 92.5% (p=0.00001), TSH by 51.7% (p=0.0012), ERK protein kinase content by 86.4% (p=0.0001), JNK by 56.8% (p=0.0001), and FAK by 55.3% (p=0.00002). The levels of IL-15 also decreased by 38.1% (p=0.0001), PG E2 by 39.5% (p=0.0001), and STAT3 by 52.5% (p=0.0001).&#x0D; CONCLUSION: The nature of the identified relationships among the analyzed factors allows us to consider AT II as a factor that ensures adaptive coupling of immune and neuroendocrine regulatory mechanisms in patients with coronary artery disease, contributing to a change in the balance between macrophages and T-helper types 1 and 2.

Experiment on Compressive Properties and Microscopic Analysis of Sea Sand Geopolymer-Based Recycled Concrete.

For marine and coastal engineering, construction resources have become scarce due to a limited local supply. Sea sand geopolymer-based recycled concrete (SSGRC) is an innovative cementitious material known for its eco-friendly benefits and corrosion resistance. This study explores the mechanical properties of SSGRC. The influences of the replacement rate of mineral slag, alkali activator concentrations, fine aggregate types, and curing ages on the compression strength of SSGRC were studied. The failure mechanism was analyzed using the failure patterns and compressive stress-strain curves. The results show that sea sand had a positive effect on geopolymer-based material. The SSGRC reached peak strength with an alkali activator concentration of 10 mol/L and a mineral slag replacement rate of 60%. The maximum stress and strain increased with an increasing curing age. The ratios of strength to the peak value were 55% and 85% after 1 day and 7 days, respectively. Using SEM, in the last hydration stage, the C-(A)-S-H gel was formed with a dense microstructure, and the geopolymer exhibited a favorable bonding performance. The constitutive models describing the complete stress-strain relationship under compression were developed.

Mechanical properties and environmental characteristics of the synergistic preparation of cementitious materials using electrolytic manganese residue, steel slag, and blast furnace slag

The high content of heavy metals in electrolytic manganese residue (EMR) makes it difficult to utilize in engineering, and direct disposal can pose a threat to the environment. This study uses EMR as a raw material combined with steel slag (SS) and blast furnace slag (GGBS) to prepare electrolytic manganese residue-based cementitious material (ESGM) under the action of an alkali activator (NaOH), and studies the effects of the EMR to SS ratio and alkali activator concentration on the flowability, setting time, compressive strength, and toxic leaching of ESGM. In addition, XRD, FTIR, SEMEDS, and MIP were used to study the microscopic characteristics of ESGM and its stabilization/solidification mechanism for heavy metals. The results indicate that an increase in EMR content will reduce the fluidity and setting time of the slurry, while an increase in alkali activator concentration will increase the fluidity of the slurry and reduce the setting time. When the content of EMR, SS, and GGBS is 50%, 20%, and 30%, respectively, and the concentration of alkali activator is 0.2, the strength of ESGM reaches its maximum, reaching 23.0 MPa in 28 days. The heavy metal leaching in ESGM is lower than the allowable range of Chinese standard GB 89781–996, and the material meets environmental requirements. The microscopic analysis showed that the ESGM gelling products were mainly C-(A)-S-H and N-A-S-H gels, and the formation of ettringite was also observed. Mn2+ in EMR was mainly stabilized in ESGM in the form of MnO2 and H2Mn8O16·2.4 H2O.

ОЦЕНКА ЭФФЕКТИВНОСТИ МОДИФИКАЦИИ ГЕОПОЛИМЕРНОЙ СИСТЕМЫ МИНЕРАЛЬНЫМИ НАПОЛНИТЕЛЯМИ С ТОЧКИ ЗРЕНИЯ ФОРМИРОВАНИЯ ПРОЧНОСТНЫХ ХАРАКТЕРИСТИК

Geopolymers, due to their positive features, can fully compete with traditional Portland cement analogues, and often have other valuable properties that can significantly expand the scope of application of mineral binders for construction purposes. This seems possible due to a wide range of raw materials of different origins, as well as a result of the use of modifying additives of different nature, morphology and, as a consequence, functionality. As part of this work, the effect of some formulation factors was studied: the concentration of the alkaline activator, as well as the type and content of the modifying agent on the strength characteristics of a geopolymer binder based on fly ash. The results of the study made it possible to establish that an increase in the concentration of the alkaline component negatively affects the effect of the modifier. Modification of the geopolymer binder with Portland cement in the NaOH concentration range from 9 to 13% leads to strengthening of the geopolymer system with an increase in its content. With a further increase in the concentration of the alkaline activator, it initiates a softening effect from the introduction of Portland cement. In turn, modification with kaolin and metakaolin leads to a decrease in compressive and bending strength characteristics throughout the entire range of alkali concentrations under consideration. Moreover, the higher the alkalinity of the geopolymer matrix, the more pronounced the softening effect takes place.

Durability assessment of mechanochemically activated geopolymer concrete with a low molarity alkali solution

The prevailing practices of geopolymer concrete (GC) preparation use a high concentration of alkali activators, which is uneconomical. It is imperative to develop GC of low-concentration activators with enhanced durability for field implementation. Mechanochemical activation of geopolymer increases the reactivity of its raw materials by converting the crystalline phase to an amorphous phase. It has been illustrated in the present study that mechanochemical activation aids in achieving GC of desired properties at low concentrations of alkali activators. The mechanochemical activation of ground granulated blast furnace slag (GGBS) with sodium metasilicate was carried out to prepare GC of low (2 M) and high (12 M) alkali concentrations. The Portland slag cement-based concrete (PC) was cast to compare the durability performance of GC. The durability of the three concrete mixes was examined in terms of water absorption, the volume of permeable voids (VPV), water and chloride permeability, homogeneity, and acid resistance. The microstructural characterization of concrete samples exposed to acid were carried out by X-ray diffraction, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. The results indicated that GC with a low concentration of activator exhibited lesser water absorption, VPV, and permeability, whereas it offered higher resistance to acids and chloride ion penetrability. Low-concentration GC had a dense and compact structure due to the coexistence of geopolymeric and hydration products, leading to better performance than high-concentration GC and PC. The evaluation of cost and carbon emission of PC, and GC mixes suggests GC as a sustainable alternative to traditional concrete. Although PC is economically viable, the study suggest use of GC with low alkali concentration due to its environmental benefits with a minor increase in cost.

Pemanfaatan Eceng Gondok sebagai Adsorben dengan Perlakuan Awal untuk Menurunkan Kadar Logam Berat Cu

Industri kimia yang dalam prosesnya menggunakan katalis tembaga ataupun garam tembaga biasanya dalam limbah yang dibuang ke lingkungan juga akan terikut logam berat tembaga (Cu). Mengingat bahaya yang ditimbulkan oleh logam berat tembaga, maka dilakukan upaya untuk mengurangi kadar limbah tembaga di perairan. Salah satu metode yang dapat mengatasi kelebihan logam Cu adalah dengan proses adsorpsi. Proses adsorpsi memiliki banyak keuntungan, diantaranya dalam pengadaan media lebih ekonomis dan tidak men-imbulkan efek samping yang beracun. Tanaman Eceng gondok merupakan tanaman yang memiliki kandungan karbon cukup tinggi, sehingga tanaman eceng gondok berpotensi untuk dijadikan bahan baku pembuatan karbon aktif. Penelitian ini akan memeplejarari pembuatan eceng godondok sebagai karbon aktif. Proses dalam pembu-atan karbon aktif diawali dengan memasak eceng gondok dengan larutan NaOH untuk meningkatkan jumlah selulosa sebagai bahan utama pembutan karbon aktif. Kemudian eceng gondok dikeringkan dan dijadikan ser-buk. Selanjutnya serbuk eceng gondok diaktivasi dengan HCl. Proses uji adsorben dilakukan dengan menam-bahkan karbon aktif pada larutan CuSO4 dengan variabel konsentrasi 2 M, 2.4M, 2.8 M, 3.2 M, 3.6 M dan waktu pengontakkan 25, 35, 50, 65, 80 menit. Hasil analisa dari metode spektrofotometri serapan atom (AAS) bahwa semakin besar konsentrasi dan waktu pengontakan maka semakin tinggi effesiensi penyerapan karbon konsentrasi aktivator 3,6 M dengan waktu pengontakan 80 menit sehingga effesiensi penyerapan Cu sebesar 42,892 %.

Physical, mechanical and microstructural properties of one-part semi-lightweight geopolymers based on metakaolin modified with gypsum and lime

The elemental composition of precursors is crucial for the performance development of geopolymers. Metakaolin (MK) was used to produce one-part geopolymers (OPG), and the influence of calcium-based components (lime and gypsum) on their properties was investigated. The experimental results show that the use of lime instead of MK increases the fluidity of the mixture, while the addition of gypsum decreases the fluidity. Meanhwlie, the use of lime to replace a small amount of MK increases the concentration of activator by consuming water and the dissolution of calcium ions also participates in the geopolymerization reaction, which enhances the mechanical properties and durability of OPG. When 10 % lime is applied, the 7-d and 28-d compressive strengths of OPG are increased by 210 % and 157.14 % compared with the plain sample, respectively. The addition of gypsum generates AFt in OPG, which reduces the compactness of the microstructure, which is not conducive to the development of the strength and durability of OPG. When 10 % gypsum is applied, the 28-d compressive and flexural strengths of OPG are decreased by 32.14 % and 26.67 % compared with plain samples, respectively. As the lime content increases, further addition of gypsum to OPG has a more negative effect on OPG due to the plundering of calcium ions in the lime. The 28-d dry density of OPG is between 1585 and 1729 kg/m3, which makes it have a lower thermal conductivity (0.87–0.94 W/m·K).

Improvement of Magnetic Saturation in Fe3O4@Y2O3:Eu3+ Nanocomposites Through the Manipulation of Eu3+ Activators.

Fe3O4@Y2O3:Eu3+ nanocomposites and Y2O3:Eu3+ nanophosphors were synthesized using the hydrothermal method. Nanocomposites were analyzed using X-ray diffraction (XRD), Rietveld refinements, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence (PL), vibrating sample magnetometer (VSM), and high-resolution transmission electron microscopy (HRTEM). Nanocomposites exhibit superparamagnetic behavior that improves with Eu3+, resulting in increased magnetic saturation. In contrast to Y2O3:Eu3+ nanophosphors, the Fe3O4@Y2O3:Eu3+ nanocomposites display a distinctive characteristic whereby the photoluminescence intensity increases with a reduced concentration of Eu3+. The requirement of increasing the thickness of the Y2O3:Eu3+ outer layer to achieve improved light emission can be circumvented by solely manipulating the concentration of activators, without compromising the magnetic saturation of the nanocomposites. The luminescent and magnetic characteristics of Fe3O4@Y2O3:Eu3+ nanocomposites can be readily optimized using straightforward synthesis parameters, making them promising candidates for potential applications in theranostic medicine.

On the optical properties of gallium based garnet phosphors according to Ca2Ln1-xCexZr2Ga3O12 (with Ln = Y, La, Gd, Lu)

Several samples of a gallium based garnet phosphor activated by cerium were investigated and reported upon in this work. Firstly, a solid solution corresponding to Ca2Lu1-xCexZr2Ga3O12 (x = 0.001–0.1), in which a doping level of 1 atom-% was revealed as the optimal activator concentration for high efficiency. Secondly, a range of samples according to the general composition Ca2(Y,La,Gd,Lu)0.99Ce0.01Zr2Ga3O12 was investigated to study the effect of different non emitting lanthanide ions on the optical properties. For this work various polycrystalline samples were synthesized and investigated by X-ray powder diffraction to determine the phase purity of the prepared samples. Fluorescence properties were examined employing excitation, emission, and diffuse reflectance spectroscopy. Temperature dependent emission spectra and fluorescent lifetimes were investigated to gain insight into the thermal quenching behaviour. From the spectroscopic investigation it was confirmed that the crystal field splitting of the cerium 5di components is strongly influenced by the size of the non-emitting lanthanide ion and the molar concentration of cerium. The change in crystal field splitting consequently shaped the excitation and emission wavelengths. Additionally, T1/2 values were determined from temperature dependent emission spectra and found to be between 230 and 250 K. Furthermore, luminescent lifetimes were calculated from pulsed laser excited decay curves. On the basis of the spectroscopy results potential applications of these phosphors are discussed.

PERANAN AKIVATOR DAN LUAS PENAMPANG KARBON AKTIF TERHADAP KEMAMPUAN ADSORPSI KARBON AKTIF PADA MINYAK GORENG BEKAS PAKAI

Used oil or used cooking oil is oil that is produced from leftover frying. The high price of cooking oil and the high need for use also makes fried traders use used cooking oil continuously which has a negative impact on health. This study aims to determine the role of activators and cross-sectional area on the adsorption ability of activated carbon produced from nipa palm shells in the process of refining used oil. The sample used is used cooking oil which is then adsorbed using activated carbon with different cross-sectional areas. Analysis of the cross-sectional area shows that variations in the concentration of NaCl as an activator in the manufacture of activated carbon from nipa palm shells affect the cross-sectional area, the higher the concentration of NaCl activator, the greater the cross-sectional area of activated carbon produced. The surface area of activated carbon activated by NaCl 0M, 4M, 6M and 8M had respective values of 11.1489 m2/g, 11.4487 m2/g, 11.5028 m2/g, 11.5079 m2/g. The results show that the greater the cross-sectional area of activated carbon, the greater the ability of activated carbon to adsorb used oil, with a value of water content and volatile matter of 0.2612% - 0.1195%, peroxide of value (POV) of 11.8629 meq/g - 5.3029 meq/g, Acid Value (AV) of 1.3368 mg KOH/g - 0.5393 mg KOH/g. Optimum results were obtained on activated carbon activated with 8M NaCL activator, this was due to the increasing concentration of the activator, more pores were formed so that the absorption capacity of activated carbon also increased.

Investigation of the Effects of Some Plant Activators Against Verticillium Wilt (Verticillium dahliae Kleb.) on Cotton

Wilt disease caused by Verticillium dahliae Kleb. is one of the stress factors affecting yield and fiber quality traits in cotton cultivation. Plant activators provide resistance by stimulating genes that activate the resistance mechanism in the plant. The aim of this study is to determine the effect of plant activators such as auxiGRO, Green Miracle, Maxicrop, ProAct Plus, and Sojall Vitanal against Verticillium wilt under both in vitro and in vivo conditions. Firstly, the effect of various concentrations of plant activators (0, 1, 5, 25, 100, 250, and 500 ppm) on mycelial growth of two fungal isolates of V. dahliae (PHCVd3-non-defoliating pathotype and PHCVd47-defoliating pathotype) in potato dextrose agar (PDA) media was investigated in vitro. The effect of plant activators on V. dahliae was determined in tolerant cotton plants (cv Carmen) and susceptible cotton plants (cv Acala SJ2) in two different ways seed coating and foliar application in vivo. In vitro experiments were carried out with three replicates, and in vivo experiments were with five replicates depending on a completely randomized plot design. 500 ppm dose of all plant activators inhibited the mycelial growth of both isolates by approximately 90%. The lowest disease index (DI) against PHCVd3 was determined as 1.43 in the tolerant cv Carmen with seed coating of auxiGRO. The lowest DI against PHCVd47 was found in Sojall Vitanal and ProAct Plus at 2.09 and 2.12, respectively. The lowest DI against both isolates was found as 1.42 and 2.18 in cv Carmen by foliar application of ProAct Plus, respectively. Plant activators did not show any inhibitory effect on disease severity against both isolates in cv Acala SJ2. The combination of tolerant cultivar + plant activators can be suggested against Verticillium wilt disease as an alternative control.