Indonesian Journal of Chemical Analysis (IJCA)

Effect of Gondorukem (Arpus) Adhesive Composition on Organic Waste-Based Briquettes using Biodrying Technology

Ridwandi — 2025-03-30

Briquettes are an alternative to coal, wood, and fossil fuels. Briquettes can be made with simple, inexpensive materials. The adhesive is gondorukem (arpus), which is easy to find. Making briquettes involves preparing raw materials, mixing adhesives with organic waste, and testing the finished product. The adhesive variations used were 5, 10, 15, 20 and 25%. Briquettes made with 5% gondorukem (arpus) adhesive had the lowest ash content. Briquettes with 25% gondorukem (arpus) had the highest ash content at 8.31%. Adhesives affect ash content. Moisture content analysis obtained with a value of 9.49% to 10.30%, the value is stable. The volatile content is 3.41-4.66%, which meets the SNI 01-6235 2000 standard. Calorimetry, all samples except 5% adhesive meet SNI 01-6235 2000 with minimum 5000 Cal/g (20934 J/g). Briquettes had density values of 0.0034176-0.004359 g/cm³, affecting energy content and combustion. Bound carbon analysis showed that all samples met the standard value of SNI 4931-2010. The burning rate of organic waste-based briquettes with different adhesives is 27 to 39 minutes, with a weight of 3.108 to 4.753 g/min. Briquettes take 66-111 seconds to ignite. SEM analysis shows rod-shaped substances, indicating organic waste and adhesives. The fibers visible are from the organic waste.

Uncertainty of Routine pH Measurements Evaluated by the Principle of Pooled Calibrations

Jens Enevold Thaulov Andersen — 2025-03-30

In the digital age, taking logarithms of data is no longer necessary when assessing pH measurement uncertainties. The focus is now on using raw, unaltered data. Routine pH measurements often differ from those in reference labs, so quantifying these differences is necessary. The uncertainties of pH values at 25°C were evaluated using mass-by-mass calculations, along with comparisons between two pH meters. Four buffer systems and several beverage samples were tested. Expanded uncertainties (U) of up to U = 0.36 were observed for pH values between 2 and 11, significantly higher than those reported by manufacturers. While measured pH values were slightly higher than calculated ones, overlapping confidence intervals allowed the data to be combined. Due to significant uncertainties, the reliable pH range was limited to 1 < pH < 11, potentially narrower (1 < pH < 6.5). Routine pH measurement uncertainties did not match those based on the PoPC, with notably high CV values for proton activities at pH values below the buffers' pKa.

Optimization of pH Conditions for Lead Adsorption using Ion-Imprinted Polymer (IIP) with EDTA as Ligand

Yuliani Permatasari — 2025-03-30

Ion-imprinted polymers (IIPs) are selective adsorbents for heavy metal removal. In this study, IIPs were synthesized using Pb²⁺ as a template, EDTA as a ligand, methacrylic acid (MAA) as a monomer, and ethylene glycol dimethacrylate (EGDMA) as a crosslinker via precipitation polymerization in an ethanol-acetonitrile mixture with benzoyl peroxide (BPO) as an initiator at 70°C. FTIR analysis confirmed the successful synthesis of IIPs by identifying Pb-O vibrations at 530.1 cm⁻¹ in the non-imprinted polymer (NIP), which disappeared in IIP after Pb²⁺ removal. SEM-EDX analysis showed IIP had more voids than NIP due to Pb²⁺ removal, with decreased Pb content from 1.85% to 0.18%. Adsorption was tested at pH 4–9, a 30-minute contact time, and an initial Pb²⁺ concentration of 50 ppm. The optimum pH was 7, with an adsorption capacity of 47.52 mg/g and a percentage recovery of 97.3%. This method offers higher selectivity, stability, and reusability due to the polymer matrix's specific Pb²⁺-imprinted cavities than other adsorption methods. Adsorption occurred via electrostatic interactions and complex formation. These results demonstrate that IIPs are effective for Pb²⁺ removal, offering a promising solution for heavy metal pollution treatment.

Reduction of Organic Pollutant Levels in Slaughterhouse Wastewater Using the Electrocoagulation Method

Hanif Hanif — 2025-03-30

The increasing demand for meat has increased the number of livestock slaughtered. An increase in cuts means an increase in the waste generated. One of the wastewater treatment techniques is the aluminium (Al) plate electrocoagulation method. Electrocoagulation is a coagulation process or coagulation and deposition of fine particles in wastewater by utilizing electrical energy through an electrolysis process so that it can degrade pollutants or contaminants in RPH liquid waste. This research was conducted to determine the effect of variations in current density and contact time and their effectiveness in reducing levels of COD and TSS, as well as increasing DO and optimum pH changes in abattoir waste. The current density variations used are 40, 45 and 50 A/m²with 30, 60, 90, 120, 150 and 180 minutes of contact times. The effectiveness of electrocoagulation on the decrease in the highest TSS value was 96.04%, and COD was 76.81%, with a contact time of 180 minutes and a current density of 50 A/m2. The pH value increased at 50 A/m²current density with a contact time of 180 minutes, an increase from 5.9 to 8.1, and the DO value increased at a current density of 50 A/m²with a contact time of 180 minutes, an increase from 1.2 to 4,3 mg/L.

Optimization of Fe Leaching Method for Indonesia Laterite Rocks using Experiment Design Central Composite Design (CCD)-Response Surface Methodology (RSM)

Rasikha Alifah Hernanda — 2025-03-30

This study's goal is to maximize the soil's iron revocation process by exploiting the CCD (Central Composite Design) and RSM (Response Surface Method) experimental designs. Kendari, Kolaka, and Southeast Sulawesi are the laterite rocks used in this study. XRF testing is used to identify the mineral components contained in laterite rocks. The iron content of the laterite rocks is 68.90% according to XRF analysis, and the remaining metal content needs to be separated by leaching. Variations in the S/L ratio, leaching time, and leaching temperature were used in the leaching process, and these changes had an impact on the amount of extracted iron. Atomic Absorbtion Spectroscopy (AAS) is used to assess the leaching process results and quantify the iron concentration. Using CCD-RSM to optimize process settings, ideal conditions are achieved at a 1:1 S/L ratio, a 90-minute leaching period, 80°C, and a 19.20% iron extraction concentration. As a result, this study not only increases the iron's efficiency but also offers a technique that may be used to extract additional metals from lateritic rocks or comparable materials.

Synthesis of a Cellulose/PVA Adsorbent Composite from Pineapple Leaves Waste (Ananas Comosus) for the Degradation of Methylene Blue in Aqueous Solution

Novi Eka Mayangsari — 2025-03-30

Methylene blue is disastrous for the environment due to their high toxicity. This needs to be mitigated to ensure that the effects can be reduced. Pineapple peel waste (Ananas comosus) can be valorized as cellulose adsorbent and cellulose/PVA adsorbent is a potential solution to minimize the impact of these contaminants. The objective of this research is to investigate the performance of the cellulose/PVA composite in the methylene blue adsorption process and to evaluate its performance with a cellulose adsorbent. The adsorption process results showed that the percentage of MB removal reached 94.03% on the cellulose/PVA adsorbent with 9% NaOH delignification for 90 minutes. After adding PVA, there was a significant increase in the removal of methylene blue in the adsorbent was recorded. The results indicate that cellulose and cellulose/PVA composites are more effective adsorbents than cellulose alone for removing methylene blue.

Analysis of Process Variables Effect on The Efficiency of Soxhletation Extraction of Larvae Oil (Hermetica illucens) using Response Surface Methodology

Murni Fitria — 2025-03-30

Maggot or Black Soldier Fly (BSF) larvae can be used as a source of oil because they have a high lipid content. In this study, the maggot oil extraction process was optimised using the soxhlet method with the assistance of the response surface methodology (RSM) using the Central Composite Design (CCD) research design. Optimization was carried out with variations in the ratio: solvent (1: 7, 1: 10 and 1: 13 g/mL) and extraction time (120, 240 and 360 minutes). The results of the significance test using ANOVA showed that the sample solvent comparison had an insignificant effect (p-value: 0.060). In contrast, the extraction time had a significant effect (p-value: 0.000) on the maggot oil harvest yield. The results of different analyses showed a significant quadratic interaction between the sample solvent comparison (p-value: 0.002) and a significant interaction between the sample solvent comparison and extraction time (p-value: 0.008). The recommended optimal conditions based on optimization using RSM are a combination of a sample solvent ratio of 1:8.5 and an extraction time of 360 minutes with a predicted oil yield of 32.11%. Meanwhile, experimental validation at the recommended optimal conditions produced a yield of 38.68% or greater than the predicted value. The characteristics of the maggot oil obtained had a density of 0.9493 g/mL, a viscosity of 0.92 Pa.s, an air content of 0.0847% w/w, and free fatty acids of 4.56%. The results of GC-MS analysis of maggot oil showed a total of 9 compounds, with the 3 most abundant compounds being oleic acid (52.6%), palmitic acid (24.78%), and lauric acid (12.45%).

Modification of Screen-Printed Carbon Electrode (SPCE) by Magnetic Fe3O4-Chitosan for Detection of Hexavalent Chromium

Ani Mulyasuryani — 2025-03-30

A new modification of screen-printed carbon electrode (SPCE) with magnetic Fe₃O₄-chitosan has been developed. Magnetic Fe₃O₄-chitosan was made from a mixture of Fe²⁺/Fe³⁺ (1:2) with 1% chitosan. Sodium tripolyphosphate was used as a crosslinking reagent for chitosan under alkaline conditions using NH₃. SPCE modification with Fe₃O₄ can increase the sensitivity of Cr(VI) detection by differential pulse voltammetry (DPV). This method resulted in a sensitivity of 21.9 ppm/μA in the 0.1 - 1 ppm Cr(VI) concentration range in a 0.005 M KCl-HCl electrolyte mixture. The detection limit (LoD) is 0.2 ppm with an average accuracy of 94%.

Development of Non-Enzymatic Glucose Sensor Using Ag-Au Bimetallic Modified Pencil Lead Electrode with Voltammetry Method

Rahmida Marlini — 2025-03-30

Glucose is an essential monosaccharide that serves as the main source of energy in the human body. An imbalance in glucose levels in the body can lead to serious metabolic disorders, such as diabetes mellitus. Therefore, effective methods of analyzing and monitoring glucose levels are needed for early detection and more optimal disease management. In this study, a non-enzymatic glucose sensor based on Pencil Lead Electrode (PLE) modified with silver-gold (Ag-Au) bimetallic was developed through electrodeposition method using cyclic voltammetry. This modification aims to improve sensitivity and cost efficiency in glucose detection compared to enzymatic sensors, that are susceptible to denaturation and higher production costs. Electrodeposition is performed in a potential range of 1.6 V to -0.4 V to obtain an optimal bimetallic coating on the PLE surface. The Ag-Au/PLE electrode provided the best electrochemical response in detecting glucose, with oxidation and re-oxidation peaks at +0.01 V in 0.1 M KOH as a supporting electrolyte. The optimal condition was obtained in five electrodeposition cycles, with a correlation coefficient value of 0.9984 and a detection limit of 0.206 mM, indicating high sensitivity and accuracy. These results indicate that Ag-Au/PLE electrodes have great potential as reliable, sensitive and economical non-enzymatic glucose sensors.