Sürdürülebilir Kalkınma Amaçları
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- MakaleAçık Erişim2025A strategy for the one-pot direct production of 5-hydroxymethylfurfural (HMF) from sucrose using organic weak acid in situ as a catalyst
Gül, Abdulkadir; Tanyıldızı, Muhammet Şaban
5-Hydroxymethylfurfural (HMF), which can be produced in high yields by acid-catalyzed dehydration of carbohydrates, is used as a feedstock in biofuel and biopolymer production. However, these acidic catalysts are usually added externally, which increases HMF production costs. Furthermore, other important parameters for high yields of HMF production are raw material selection, reaction medium, and separation-purification processes. The aim of this study is to produce HMF in one-pot without the addition of any exogenous catalyst by evaluating the fructose remaining in the production medium in which the glucose from sucrose hydrolysis is microbially fermented into gluconic acid (GA). HMF production from fructose in a biphasic system consisting of a fermentation liquid containing GA and fructose and 2-Methyltetrahydrofuran (2-MeTHF) was optimized using Central Composite Design (CCD). The variables examined included reaction time, reaction temperature, solvent type, salt type, and organic/aqueous phase ratio. In the study, by chelating GA and calcium ions, the low degree of ionization of GA was increased, and HMF was produced in high yields without the addition of a catalyst. Under optimum conditions, using 2-MeTHF/ fermentation liquid (6:1) and 7.56 wt% CaCl2, the yield of HMF produced in pressurized (hydrothermal) vessels at about 147 °C for 158 min reached 77.6 % of the theoretical yield. The amount of GA in the production medium was 92.64 % preserved from degradation. GA and HMF in different phases of the biphasic system were purified from the production medium in high yields. Furthermore, 2-MeTHF, which constitutes the organic phase of the biphasic system, was recovered at approximately 95 % by vacuum evaporation. As a result, HMF production from sucrose, which is a more economical and abundant raw material compared to glucose and fructose, was realized in one-pot without the addition of any catalyst.
- MakaleAçık Erişim2024Gluconic Acid Production by Using Recombinant Escherichia coli Waksman pqq+ Cells with a Novel Approach from Biomass Sources
Gül, Abdulkadir; Tanyıldızı, Muhammet Şaban
Gluconic acid (GA) is widely used in the pharmaceutical, food, detergent, textile, leather, and concrete industries. However, cost-effective and high-yield production of GA remains a challenge. Due to currently high raw material inputs of GA, various alternative carbohydrate sources are being investigated. Sucrose is one of the cost-effective biomass sources that can be used as feedstock. The most common industrial production of GA is based on wild-type bacteria and fungi, but there are many problems with this production. This study aimed to optimize the production of GA from glucose produced by hydrolysis of sucrose using recombinant E. coli Waksman (W) pqq+ strain. After sucrose was enzymatically hydrolyzed, significant medium components for GA production were determined as glucose, calcium carbonate (CaCO3), peptone, and ammonium phosphate ((NH4)3PO4) using Placket-Burman Design (PBD). Detailed optimization of the medium components that are significant in GA production was carried out using central composite design (CCD), and optimum values of the independent variables examined in maximum GA production (93.5 ± 2.95 g/L) were determined as glucose 95, CaCO3 25, peptone 2, and (NH4)3PO4 1.13 (g/L). Using results obtained in the Erlenmeyer experiments, GA production in the bioreactor was investigated by CCD. The maximum GA efficiency (3.20 ± 0.15 g/L. h) was obtained under conditions where the air supply rate was 10.82 L/min, stirring speed was 656.87 rpm, and CaCO3 concentration was 16.90 g/L. In conclusion, it has been shown that GA can be produced with a high yield with this novel approach using a recombinant strain for GA production from sucrose.
- MakaleAçık Erişim2024Central composite design modelling and developing a method for removing sulphate from an alunitic kaolin ore
Erkan, İlker; Inal, Serkan; Alp, İbrahim
The main mineral in kaolin ore, kaolinite, is well-known for its many uses in the paint, paper, and ceramics industries. The necessity of getting pure kaolinite is discussed in this work, with an emphasis on the extraction of impurities from kaolin. Specifically, alunitic kaolin, which is common in northwest Turkey, has sulfur concentrations higher than 3 % SO3, which means that it can't be used for many industrial purposes. Leaching is a popular method for removing sulfur, especially when done directly and through pre-treatment techniques like roasting. High-temperature roasting, however, presents difficulties since it causes phase transformation on kaolinite to metakaolin and mullite and on alunite to alum. The temperature of phase transformation is important on high temperature studies which affects negatively the thixotropic qualities that are essential for the production of ceramics. This study introduces a novel approach by optimizing roasting conditions and employing a central composite design methodology for leaching. The optimal parameters for the roasting studies were determined to be 525 °C for 3 h. For leaching, the ideal conditions were identified using the leaching recovery equation, which specifies 0.195 M NaOH, 80 °C, 127 min, and a 2.55 % solid content. These characteristics were confirmed by follow-up experiments, which showed a change in SO42− concentration from 3.03 % to 2.97 %, along with some structural changes in the roasted sample. The subsequent leaching process resulted in a significant drop in SO42− concentration to 0.46 %. By highlighting the effectiveness of lower-temperature roasting and optimizing experimental methodology, this research presents a novel thermochemical method for sulfur removal in alunitic kaolin.