Acid-base Titration Method Research Articles

Effect of Red Guava (Psidium guajava L.) Juice Concentration on Product Quality and Antioxidant Activity of Red Guava Synbiotic Yoghurt

Red guava juice has very strong antioxidant activity and has the potential to be processed into synbiotic functional beverage products that have health benefits. This study examined the effect of red guava juice concentration on product quality and antioxidant activity of red guava synbiotic yoghurt. Product quality tested included microbiological quality (total LAB) and chemical quality (pH value and Total Tritable Acid (TTA )value). The concentrations of red guava juice used were 0%, 10%, 20%, 30%, and 40%. Fermentation was carried out for 6 hours at 37⁰C by Lactic Acid Bacteria (LAB) from powdered mixed culture. Then organoleptic testing using the hedonic test, total LAB testing using the Total Plate Count (TPC) method, pH value testing using a pH meter, TTA value testing using the acid-base titration method, and antioxidant activity testing using the DPPH (2,2-diphenyl-1-picrylhydrazil) method. Test data were analyzed using SPSS software to determine the effect of red guava juice concentration on test results. The concentration of red guava juice in red guava synbiotic yoghurt affects the pH value, TTA value, and IC50 value as the result of antioxidant activity testing. Red guava juice concentration did not affect total LAB testing. Organoleptic assessment of red guava symbiotic yoghurt is in the range of like to like very much. The best formulation was red guava synbiotic yoghurt with 30% red guava juice concentration, which had strong antioxidant activity with an IC50 value of 59.637 ppm, pH value of 3.94, TTA value of 1.98%, and total LAB as much as 1.81x10⁸ colonies/g, so it has met the quality requirements of yoghurt according to Indonesian National Standard SNI 2981: 2009.

Sulfonated graphitic carbon catalyst derived from coffee waste: A sustainable valorization approach for highly efficient production of 5-hydroxymethylfurfural (5-HMF) from fructose

According to recent research, a sulfonated 2D graphitic carbon catalyst for the dehydration of fructose to the platform chemical 5-Hydroxymethylfurfural (5-HMF) can be made from used ground coffee. By carbonizing and activating at different temperatures, sulfonated graphitic carbon (SC) catalysts with varied chemical compositions and textural characteristics were obtained. The physical and chemical characteristics of the SC catalysts were assessed using XRD, Raman, SEM-EDX, HR-TEM, BET analysis, and XPS. Due to its microporous structure, SC-900 exhibited a high specific area and demonstrated selective and efficient production of 5-HMF from fructose. All in all, the surface acidity of catalysts was measured by NH3-TPD, and acid-base titration methods. The SC-900 catalyst, designed through carbonization at 900 ℃, achieved a fructose conversion rate of 100 % and a 5-HMF yield of 97.91 % without generating any by-products. This indicates the catalyst essentially produces 5-HMF under the specified optimal conditions (140 ℃, 90 min) observed in this study. To determine the origins of the highly efficient and highly selective conversion of fructose to 5-HMF, the performance of the SC catalysts was systematically investigated vi-a-vis their physical and chemical properties. The development of microporous SC catalysts and their application as catalysts not only enhances the value of waste coffee but also provides an environmentally friendly approach for converting carbohydrates into 5-HMF.

Determination of insoluble (INSOL) calcium content in Cheddar, Feta, Juustoleipa, and Mozzarella cheeses using acid-base buffering curves

The amount of colloidal calcium phosphate (CCP) complex associated with caseins (INSOL Ca) determines the body, texture, flavor and breakdown of cheese constituents during aging. The continuous pH decline during cheese making because of lactic acid fermentation results in solubilization of insoluble (INSOL) calcium. Measuring INSOL Ca in such a dynamic and wide range pH system (6.6 to 5.3) is challenging. The purpose of this study was to test utility of acid-base auto-titration method in differentiating INSOL Ca content in cheeses with a wide range of pH (i.e., Juustoleipa 6.6, Mozzarella 5.6, Cheddar 5.3, Feta 4.8) and also to understand the relationship between pH, protein content, and INSOL Ca. A positive relationship was obtained for pH (R2 = 0.62) and protein content (R2 = 0.85) with INSOL Ca, suggesting concomitant release of CCP content at lower pH values and association of higher amount of CCP with higher protein content. Despite having a pH slightly closer to Mozzarella (pH 5.56), Cheddar cheese (pH 5.25) had more INSOL Ca (0.67%) owing to the highest amount of protein (26%) and low moisture content (33%). Feta had the lowest amount of INSOL Ca (0.15%) owing to a low pH (4.79), higher moisture content (55%), and low protein content (14%). Juustoleipa had the highest percentage of INSOL Ca out of total calcium (88%) due to higher pH (6.62) and more intact casein. It was evident that the acid-base titration method was able to differentiate INSOL Ca between different types of cheeses with varying pH and protein content. Findings of this work will help tracking the proportion of INSOL Ca at various stages of cheese making and understanding kinetics of INSOL Ca solubilization and its role in causing pH variation in the early stage of cheese ripening.

Effect of Chitosan Addition on Porosity of Rice Husk Calcium Silicate Used for Free Fatty Acid Adsorbent from Palm Oil

Studies have been done on developing calcium silicate pores derived from rice husk with and without including chitosan as a template. The chitosan solution was supplemented with sodium silicate derived from rice husk, and then CaCl2 was added. The calcium silicate was calcinated at 900ºC for 4 h. The calcium silicate obtained was characterized using X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Brunauer-Emmett-Teller (BET) analysis. The XRD analysis showed the presence of diffraction peaks corresponding to Wollastonite (CaSiO3) crystals, Wollastonite 2m (CaSiO3), Alite (Ca3SiO5), and larnite (Ca2SiO4). Next, the FT-IR spectrum exhibits Si-O-Si, Si-O-Ca, and Si-OH functional groups, suggesting the presence of calcium silicate material. The BET study of calcium silicate using chitosan templates revealed a pore size of 3.88 nm, a pore volume of 0.1577 cc/g, and a surface area of 81.1519 m2/g. The BET analysis results obtained differed from those of the BET analysis of calcium silicate conducted without using chitosan templates, which were 2.06 nm, 0.069 cc/g, and 13.531 m2/g, respectively. The developed mesoporous calcium silicate was employed as an adsorbent to decrease the concentrations of free fatty acids in palm oil. The acid-base titration method is used to evaluate quantities of free fatty acids. The results obtained from the computation of free fatty acid levels indicate a decline in the concentration of free fatty acids in palm oil. The concentration of free fatty acids derived from palm oil was 1.23%. Therefore, mesoporous calcium silicate-free fatty acids at a concentration of 1.06% resulted in an 86.1% reduction.

Electron beam-assisted exfoliation of boron nitride and covalent functionalization

A facile, scalable exfoliation technique is still required for further modification to cater to any potential application for two-dimensional boron nitride. This paper discusses the radiation-assisted exfoliation of hexagonal boron nitride (h-BN) using electron beam irradiation and followed by functionalization with phosphoric acid 2-hydroxyethyl methacrylate ester (PA) to facilitate targeted applications. h-BN is dispersed in NaOH solution and subjected to mild sonication to facilitate ion intercalation between the layers. The sonicated h-BN solution was exposed to electron beam irradiation for BNNS exfoliation. The degree of exfoliation was measured in terms of d-spacing derived from XRD using Bragg's law. The effect of irradiation dose, energy, NaOH concentration, and mass of h-BN, on exfoliation degree was investigated. XRD analysis was used to compute the d-spacing, crystallinity, and crystal size of h-BN after irradiation. The d-spacing attained for pristine h- BN was 0.334 nm, however it increases to 0.337 nm upon irradiation at 100 kGy doses, 3 MeV of energy, and 0.1 g of h-BN in 80 mL of 30 % NaOH solution. The occurrence of radiation-assisted exfoliation and its mechanism were supported by FTIR, TGA, Raman, FESEM, XPS, AFM, and TEM analyses. The exfoliated BN was functionalized with PA. The degree of functionalization was measured by phosphoric density (mmol/g) via the acid-base titration method. The effect of PA concentration, reaction temperature and mass on phosphoric density was also investigated. The highest phosphoric density attained was approximately 13.32 mmol/g at 10 % PA, 0.1 g of exfoliated BN, 80 °C, and 5 h. The incorporation of PA onto exfoliated BN was further confirmed by XRD, FTIR, TGA, Raman, FESEM-EDX, and XPS analyses. Conclusively, this study reveals a facile dual-step exfoliation and functionalization technique of h-BN nanosheet through radiation assisted exfoliation technique.

Identification of acetic acid levels in ecoenzyme from organic materials of orange peel with acid-base titration method

This study aimed to elucidate the comparison of the levels of acetic acid and the pH of the ecoenzymes from organic matter variations of sweet and sour orange peels. The acetic acid is an organic compound containing a carboxylic acid group which is also widely applied in the health and industrial fields. Preparation of acetic acid from substrate products containing ethanol which can be obtained from fruit ingredients including oranges. One of the uses and management of organic waste, including vegetables and fruit, is by making ecoenzymes from fruit peels with a mixture of water and sugar. Fruit peels that can be used as organic ecoenzyme ingredients vary widely, so the content in ecoenzymes becomes very diverse and tends to be unstable. This type of research is descriptive. This study consisted of three stages, namely the manufacture of ecoenzymes from pasaman orange peel, gunung omeh, kaffir lime and lime in 7 variations (for 100 days), measurement of acetic acid levels and pH in the ecoenyzme samples for 14 days and 100 days. Acetic acid levels were determined using the acid-base titration method. The results of this study showed that the highest levels of acetic acid ecoenzyme in the 100-day fermentation were 5.53% in the sour orange group, while the lowest in the mixed ecoenzyme was 3.32%. The most acidic ecoenzyme pH was at 100 days of fermentation (pH ±3.5).

Solvent-free synthesis of jasminaldehyde over chitosan–layered double hydroxide catalyst assisted by microwave irradiation

This research paper reports on the use of chitosan-modified layered double hydroxide (LDH) composite catalysts (CS/MgAl–NO3) for the synthesis of jasminaldehyde under microwave irradiation. The catalysts were prepared by co-precipitation in an inert nitrogen atmosphere. The resulting samples were characterized by mean of X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric/differential thermal analysis (TGA/DTA), scanning electron microscope (SEM) with energy-dispersive X–ray (EDX), and N2 adsorption/desorption isotherm (BET) analysis. The basicity of each catalyst was determined by the acid-base titration method. The performance of the catalysts was evaluated in the solvent-free synthesis of jasminaldehyde from aldol by condensation reaction between benzaldehyde and 1–heptanal in a microwave oven at P = 100 W and T = 90 °C. The effects of different parameters that are involved in the reaction, such as the catalyst amount and the benzaldehyde to 1–heptanal molar ratio, and reaction temperature, are investigated in detail. The results showed that the CS-functionalization of the catalyst leads to the enhancement of its basic sites making it more efficient than the naked MgAl–NO3 catalyst, in terms of the initial reaction rate, the conversion of the reactants and the selectivity toward the jasminaldehyde. The CS/MgAl–NO3 catalyst was also evaluated in successive regeneration reaction cycles.

Potensi Sirop Umbi Yakon sebagai Prebiotik Dadih Susu Sapi untuk Asupan DMT2

Background: The prevalence of people with Type 2 Diabetes Mellitus (T2DM) is ≥90% of the total diabetics worldwide. The formulation of dadih of cow’s milk with the addition of yacon tuber syrup can potentially be a synbiotic product. Consumption of synbiotic products in people with T2DM can provide a glycemic control effect. Objective: Analyzed the effect of adding yacon tuber syrup on total lactic acid bacteria (LAB), pH, total acid, and acceptability of cow’s milk dadih. Method: The research design was experimental with a single-factor completely randomized design (CRD) and three repetitions. The method used to analyze the total LAB test uses total plate count (TPC), the pH test using a pH meter, the total acid test using the acid-base titration method, and the acceptability test using an organoleptic test with a hedonic scale (1-9). Results: the addition of yacon tuber syrup affected the pH value (p= 0,016). While, it did not show a significant effect (p>0,05) between the addition of yacon tuber syrup on total LAB, total acid, and organoleptic. Conclusion: Product F2 with added 20% yacon tuber syrup was the best formula with the highest total LAB and acceptability.

Bioprospecting of Lactobacillus sp. Starter Culture from Colostrum Breast Milk for Probiotic Milk Production from Soybeans

Lactobacillus sp. is a bacterium that naturally exists in various environments, including in breast milk colostrum. This bacterium belongs to a group of lactic acid bacteria that produce lactic acid as the main product of sugar fermentation so that it has probiotic properties that also play a role in the fermentation process. This study aims to produce probiotic milk using Lactobacillus sp isolates from breast milk colostrum with soybean (Glycine max (L.) Merril.) as the base material and then test the total lactic acid content, pH value, reducing sugar and the number of lactic acid bacteria. The production of soybean fermented milk is based on the analysis of total lactic acid content by acid-base titration method with 0.1 N NaOH standard solution, pH value by using universal pH meter, reducing sugar test by spectrophotometric method of Nelson-Somogyi and the number of lactic acid bacteria by using Glucose Yeast Pepton Agar (GYPA) medium added with CaCO3 then calculated by using Standard Plate Count (SPC) method with TPC value (Total Plate Number) is 2.3. 1012 colonies/ml, 2.5.1012 colonies/ml, 4.5.1014 colonies/ml, 4.1.1014 colonies/ml. From the results of the study it is known that Lactobacillus sp isolates from breast milk colostrum fluid can ferment soybean milk (Glycine max (L.) Merril.)

Clay-supported acidic ionic liquid as an efficient catalyst for conversion of carbohydrates to 5-hydroxymethylfurfural

Halloysite nanoclay has been used as a natural support for the immobilization of an acidic ionic liquid with multiple acidic sites. To graft the ionic liquid on the halloysite, amino-functionalized halloysite was reacted with 2,4,6-trichloro-1,3,5-triazine and 2-aminopyrimidine successively to form heterocyclic ligand on halloysite, which was then converted to acidic ionic liquids through reaction with chlorosulfuric acid. The resultant catalyst was then characterized via SEM, EDS, and elemental mapping analysis, FTIR, XRD and TGA. Noteworthy, acid-base titration method confirmed that introduction of acidic ionic liquid significantly improved the Brønsted acidity of halloysite. The catalytic activity of the catalyst was investigated for conversion of various carbohydrates to 5-hydroxymethylfurfural. Gratifyingly, the results showed that the catalyst could promote the reaction of fructose, sucrose, glucose and galactose under mild reaction conditions (catalyst (0.03 g), at 85 °C in 70 min) to give the product in high to excellent yields. Computational DFT studies unveiled the reaction mechanism, pointing out the limiting steps kinetically, and in addition how important are the non-covalent interactions. Furthermore, the recycling tests confirmed high recyclability of the catalyst up to six runs.

The Effect of Rice Varieties on Silica Purification from Rice Husk Ash as Adsorbent for Mn(II)

The influence of rice types on the purification of rice husk ash was investigated by extracting silica and purifying it with a 12% NaOH solution, followed by the coprecipitation technique. Rice husk samples were from Mbay (Nagekeo Regency) with two different varieties, Ciherang and Inpari 42, and from Soa (Ngada Regency) with Ciherang variety. The silica produced in this research was characterized using UV Vis spectrophotometry to obtain the surface area value. The surface acidity value was calculated using the acid-base titration method. Using XRF, the purity of silica was determined. Ciherang Mbay, Ciherang Soa, and Inpari Mbay had surface area values of 18.397 m2/gram, 18.347 m 2 /gram, and 18.491 m 2 /gram, respectively. The surface acidity value of the three samples was 45.1 mmol/gram, 45.5 mmol/gram, and 44.7 mmol/gram, respectively. The purity of silica from rice husk ash Ciherang Mbay, Ciherang Soa, and Inpari Mbay samples based on XRF was 98.6%, 98.3%, dan 99.2%, respectively. Silica with the highest purity (Inpari Mbay variety) was applied as an adsorbent in the adsorption process of manganese (Mn(II)) metal ion with an adsorption capacity of 212.76 µmol/gram and adsorption energy of 38.165 kJ/mol through chemical adsorption. Keywords : purification, rice varieties, silica, adsorption, manganese

Development and Validation of New Methods for Quality Control of the Antiviral Substance FAVIPIRAVIR

The introduction into the production of medicinal substances involves the creation of a pharmaceutical dossier, an important component of which is data on pharmaceutical development and quality control methods. The physico-chemical properties of the antiviral substance of favipiravir were investigated, and some basic sections of the analytical documentation were developed. With the help of a complex of physical, chemical, and physico-chemical methods of analysis, the "Identification" test was developed, and the structure of favipiravir was proven. Methods for the determination of related substances by the HPLC with UV detection and the assay of favipiravir by the acid-base titration method, suitable for substance quality control, have been developed. Relative retention times and correction factors for calculating their content are established for all impurities. The methods were validated on the parameters of specificity, accuracy, correctness, and linearity in the studied range of concentrations.

A comparative assessment of chemical characteristics of goat’s milk yoghurt after the addition of Syzygium cumini L.

Introduction: Yogurt is a functional food that has health benefits. The study aimed to analyze the physicochemical characteristics of goat’s milk yogurt after adding Syzygium cumini L. Methods: Syzygium cumini L extract was mixed into goat’s milk and starter (Streptococcus thermophilus and Lactobacillus bulgaricus) and then fermented at 250C for 24 hours. The samples were divided into 4 treatment groups, namely differences in the concentration level of the addition of Syzygium cumini L (0%, 20%, 40%, 60%). The pH levels were analyzed by pH meter, lactic acid levels by acid-base titration method, and dietary fiber content by enzymatic gravimetric method. Results: The results showed that the pH level without adding Syzygium cumini L was 4.81 while Syzygium cumini L decreased by 0.5-0.8 to become more acidic. Meanwhile, the addition of Syzygium cumini L increased the lactic acid level by 4.82% by 0.2-0.5%. Dietary fiber content increased from 2% to 2.10% with the addition of 60% Syzygium cumini L. This study showed a difference in the chemical characteristics of pH, lactic acid, and dietary fiber between goat’s milk yogurt before and after the addition of Syzygium cumini L. Conclusion: This study has identified a significant difference in characteristic physicochemical on pH level, lactic acid level, and dietary fiber content between goat’s milk yogurt before and after the addition of Syzygium cumini L.

MODIFIKASI SILIKA GEL DARI ABU LIMBAH HASIL PROSES PEMBAKARAN INDUSTRI BATU BATA DENGAN DIFENILKARBAZON SEBAGAI ADSORBEN SERTA UJI DAYA SERAP TERHADAP ION LOGAM Cr(III) DAN Cu(II)

The modification of silica gel, from the waste of the bricks burning process, with diphenylcarbazone has been done. The silica gel modified by diphenylcarbazone (Si-DPZon) was obtained by boiling the ash with NaOH solution to create sodium silicate and neutralized with HCl to get the silica gel, then physically modified with diphenylcarbazone ligand. The study included the determination of the adsorbent functional groups by spectrophotometer IR, surface acidity by acid-base titration method, specific surface area by absorption of methylene blue method, the optimum conditions (pH, contact time) of the adsorption of Cr(III) and Cu(II). FTIR analysis showed that the Si-DPZon contained amide (N-H), carbonyl (C=O), silanol (Si-OH), siloxane (Si-O-Si) and aromatic (C-H) functional groups. The results showed that Si-DPZon had a surface acidity (Kal) of 5.8384 ± 0.2466 mmol/g with the number of active sites of 12.3945x1020 atom/g with a specific surface area of 12.6886 m2/g. Si-ABB had a surface acidity (Kal) of 4.5568±0,2453 mmol/g with the number of active sites of 27.4410x1020 atom/g and with a specific surface area of 11.6712 m2/g. The optimum conditions for adsorption of chromium (III), both Si-DPZon and Si-ABB occurred at pH 5 and 15 minutes. The adsorption ability of Cr(III) by Si-DPZon at the pH and contact time optimum conditions was 34.6927 mg/g with an adsorption percentage of 86.7317% and Si-ABB was obtained at 34.5445 mg/g with the adsorption percentage of 86.3611%. Adsorption ability of Cu(II) by Si-DPZon at the pH and contact time optimum conditions was 26.49672 mg/g with the adsorption percentage of 66.2418% and Si- ABB was obtained at 24.93210 mg/g with the adsorption percentage of 62.3302%.
 Keywords: adsorptions, chromium (III), copper (II), diphenilcarbazone ligand, synthesis of silica gel.

SINTESIS DAN KARAKTERISASI SIFAT FISIK DAN KIMIA KATALIS BENTONIT-ZnO

The use of bentonite clay as a catalyst has been reported by many studies. The catalytic activity of clays is generally not very high. Therefore, the clay must be modified before use. Synthesis and characterization of ZnO (Bentonite-ZnO) modified clay was carried out. This study aimed to determine the physical and chemical properties of modified Bentonite with ZnO. Bentonite was dipped first and then intercalated with ZnO which was expected to form pillars. The synthesized Bentonite-ZnO was characterized according to the benefits of Bentonite-ZnO as a catalyst using X-Ray Diffraction, SEM-EDS, FTIR, surface area using Methylene Blue adsorption method, and surface acid sites using an acid-base titration method. The characterization results showed that the intercalation of ZnO into bentonite did not increase the distance between layers, the catalyst became more homogeneous and there was an increase in the number of Zn elements, the appearance of absorption bands in the 3600; 1600 – 1650; 2900-2850 and 450 cm-1 regions which identified the functional group characteristics of Bentonite-ZnO and surface area and acid sites of 46.357 m2/g and 5.887 x 1022 sites/g, respectively.
 Keywords: bentonite, catalyst, characterization, pillared, ZnO.

A facile approach for the determination of degree of deacetylation of chitosan using acid-base titration

Several spectroscopic techniques such as nuclear magnetic resonance (NMR), UV-visible, Fourier transform infrared (FT-IR), etc. have been already used for the determination of degree of deacetylation (DD) of chitosan. These techniques involve the interpretation of spectral data apart from sample preparation for obtaining DD of chitosan. In addition, inaccurate interpretation of data sometimes misleads researchers to get an exact value of DD of chitosan. Among them, NMR is an excellent technique for the estimation of DD of chitosan but expensive and not found easily in every research laboratory. On the other hand, titrimetric methods have been employed by many researchers for determining the DD of chitosan but these existing methods involve many complex calculations, which do not always give accurate results. Moreover, few of the acid-base titration methods are little complicated for execution. Therefore, in this present study, we adopted a very handy and simple acid-base titration method with a new approach and proposed a new equation facilitating the ease of calculation that is not reported elsewhere for the determination of DD value by observing the net volume of NaOH consumed for the complete neutralization of protonated amino groups (-NH3+) of chitosan describing the novelty of the work. All the DD values (77.04 ± 1.36; 81.71 ± 1.73; 91.68 ± 1.42 for CS1, CS2, and CS3 respectively) obtained for various chitosan samples were in good agreement with the reported DD values (>75%, >80%, and >85% for CS1, CS2, and CS3 respectively) mentioned in the specifications of chitosan samples supplied by the manufacturer. Finally, the experimental DD values were further validated with the DD values (77.39%, 81.64%, and 90.5% for CS1, CS2, and CS3 respectively) obtained from the interpretation of 13C-NMR spectral data and all the experimental DD values were consistent with the DD values as calculated based on NMR spectra.

SPENT EDIBLE OIL SOAP ANALYSIS ON CHEMICAL PRACTICUM ACTIVITIES IN SMA HARAPAN III DELI SERDANG

Spent edible oil is the result of repeated frying that is mostly done in the fast food industry or in household activities and generally this used cooking oil is disposed of as waste that pollutes the waters in the environment. Spent edible oil is a good ingredient for soap making because its raw material is relatively cheaper than most oils. In a simple laboratory study conducted by students of SMA Harapan III Deli Serdang, soap was made from used cooking oil using alkaline NaOH. The saponification process was carried out using used edible oil soap 0.3 parts by mass ratio of NaOH at a concentration of 30% and 1 part of used edible oil bleached with activated charcoal. The analysis of edible oil soap that has been made by determinate the value of free alkali with acid-base titration method and foam stability test. The results obtained from the determination of the foam test provide foam stability of 83.3% and free alkali content of 0.211%. This soap provides a fairly stable foam stability, but it still feels hot in the hands due to the alkaline NaOH that is used not completely soaped in the washing process. The use of edible oil into soap by students can increase knowledge and can be applied to overcome environmental pollution due to the disposal of edible oil into the environment.

Low-cost Posidonia oceanica bio-adsorbent for efficient removal of antibiotic oxytetracycline from water.

The presence of antibiotics as micro-contaminants in the water and aqueous environments is a health concern to humans and the ecosystem. Therefore, their elimination by adsorption to available and cheap materials in water treatment plants is a research topic of high relevance. The present paper reports on the adsorption behavior of oxytetracycline on a bio-adsorbent prepared from Posidonia oceanica; an abundant Mediterranean biomass. Characterization of the pretreated Posidonia biomaterial was achieved using several analyses such as Boehm acid-base titration method, pHPZC determination, and analysis techniques (FTIR, 13C CP-MAS NMR, optical microscopy, and TGA). The pHPZC occurred around pH 2.11. Posidonia biomaterial showed a fast and high uptake rate throughout the adsorption process, which is a definite advantage for analytical applications such as water decontamination. The experimental kinetic data fitted very rightly the pseudo-second-order kinetic model and the equilibrium uptake can adopt the bi-Langmuir isotherm model for all studied pH values which assumes adsorptions at the two localized sites. Maximum adsorption capacities of 11.8mg∙g-1 and 4.4mg∙g-1 for the two adsorption sites are reached at pH 6. The oxytetracycline adsorption process onto Posidonia bio-adsorbent is spontaneous (ΔadsG0 < 0), exothermic (ΔadsH0 < 0), and entropically favorable (ΔadsS0 > 0). The effect of pH on adsorption behavior and the thermodynamic parameters of adsorption are consistent with a possible origin of adsorption of oxytetracycline by means of hydrogen bonding interactions between surface hydroxyl and phenolic groups of the biomaterial and oxytetracycline. The proposed green and environmentally friendly biomaterial offers potential benefits as a bio-adsorbent in the remediation of aquatic environments contaminated by various organic materials.

Phenolphthalein Indicator in Titrimetric Estimation of Benzoic Acid Solubility and Distribution in Water and Benzene-Buffer Solutions

In solubility and partitioning process of benzoic acid, the various factors are involved such as temperature, solute-solvent interaction and dissociation of acid into ionic state in taking solvents. Here, we reported the benzoic acid (solute) solubility in gram/100gram of solvent in different pH benzene-buffer solutions which are analyzed by using of titration method and partition study of these acid into solvents like water and benzene layer by shake-flask acid-base titration method, at room temperature (25°C) for 24 hours. In titrimetric estimation the solute benzoic acid solubility and their partition in between of water and in different pH buffer solutions as in medium of acidic, neutral and basic, a phenolphthalein indicator have been used well. The solvents and benzene-buffer solutions having different pH 4.0, 7.0 and 9.0 is titrated against as 0.01, 0.05 and 0.1N NaOH solutions by using phenolphthalein as indicator, where the end point show a pink color for each reading. Concentration of benzoic acid into water and solvent benzene layers is being calculated as by applying the equation of normality determination and distribution coefficient as from Nernst distribution law equation.

Analisis Karakteristik Fluida dan Temperatur Reservoir Dengan Menggunakan Diagram Ternary Cl-Li-B Pada Manifestasi Panas Bumi Di Desa Kaleosan, Minahasa Utara

Research on determining the fluid and temperature of the geothermal reservoir in Kaleosan village, Kalawat district, North Minahasa regency, the hot springs are 100 ml. Determination of the characteristics of geothermal fluids is carried out using the Cl-Li-B triangle diagram. The Cl-Li-B triangular diagram is used to determine the origin, boiling, and dilution of geothermal reservoir fluids. Reservoir temperature estimation is done by using silica geothermometer equation. Measurements of Li, B and Ca elements were carried out using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and measuring SiO2 compounds using Visible Spectroscopy. Measurement of Cl elements using acid-base titration method at the PT. Indonesian WLN. Based on laboratory results and data processing and field sampling, the dominant type of chloride (Cl) concentration was obtained. The results showed that the geothermal springs in Kaleosan Village are in immature water, which indicates that the geothermal reservoir fluid has undergone dilution with other elements. The geothermal system in Kaleosan Village is dominated by water and hot springs come out in the outflow zone.