Maulidan Firdaus

Bio: Maulidan Firdaus is an academic researcher from Sebelas Maret University. The author has contributed to research in topics: Chemistry & Food science. The author has an hindex of 11, co-authored 41 publications receiving 631 citations. Previous affiliations of Maulidan Firdaus include Karlsruhe Institute of Technology.

Terpene-Based Renewable Monomers and Polymers via Thiol–Ene Additions

Abstract: Solvent and radical initiator-free addition of thiols to terpenes ((R)-(+)- and (S)-(−)-limonene and (−)-β-pinene) are described as a simple approach to obtain a wide range of alcohol and/or ester functionalized renewable monomers. (R)-(+)-Limonene (1) and (S)-(−)-limonene (2), presenting different reactivity at the endocyclic and exocyclic double bonds, have yielded the monoaddition or diaddition product by simple variation of the thiol feed ratio. In the same manner, (−)-β-pinene (3) derived alcohol and ester monomers have been prepared. The monomers thus obtained have been characterized, and their behavior in polycondensation has been studied. It has been found that long chain diesters or diols, which were synthesized from a castor oil derived platform chemical, are suitable comonomers and result in polycondensates with number-average molecular weights of up to 25 kDa. Thus, terpene/fatty acid-based polyesters were prepared, and their structure–thermal property relationships were studied.

The langmuir isotherm adsorption equation: The monolayer approach

Abstract: Langmuir adsorption isotherm equation is generally derived using the kinetics approach and based on some assumptions. These assumptions are usually not accompanied by an adequate explanation related with the mechanisms and the determination techniques of its adsorption constants. This study presents a simple technique on the determination of the isotherm equation based on the main assumption so called the monolayer assumption. Furthermore, a more precise technique for determining the adsorption constants is also described. This theoretical study is supported with statistical analysis on the experimental data adapted from the literature. Two theories based on adsorption mechanism and based on rate were introduced. Regardless of its limitations, the results show that the technique for the determination is valid.

Bright Side of Lignin Depolymerization: Toward New Platform Chemicals

Abstract: Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products. Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many creative strategies emerged that deliver defined products via catalytic or biocatalytic depolymerization in good yields. The purpose of this review is to provide insight into these novel approaches and the potential application of such emerging new structures for the synthesis of biobased polymers or pharmacologically active molecules. Existing strategies for functionalization or defunctionalization of lignin-based compounds are also summarized. Following the whole value chain from raw lignocellulose through depolymerization to application whenever possible, specific lignin-based compounds emerge that could be in the fu...

Strategies for the Conversion of Lignin to High-Value Polymeric Materials: Review and Perspective

Abstract: The majority of commodity plastics and materials are derived from petroleum-based chemicals, illustrating the strong dependence on products derived from non-renewable energy sources. As the most accessible, renewable form of carbon (in comparison to CO2), lignocellulosic biomass (defined as organic matter available on a renewable basis) has been acknowledged as the most logical carbon-based feedstock for a variety of materials such as biofuels and chemicals. This Review focuses on methods developed to synthesize polymers derived from lignin, monolignols, and lignin-derived chemicals. Major topics include the structure and processing of lignocellulosic biomass to lignin, polymers utilizing lignin as a macromonomer, synthesis of monomers and polymers from monolignols, and polymers from lignin-derived chemicals, such as vanillin.

Management of validation of HPLC method for determination of acetylsalicylic acid impurities in a new pharmaceutical product

Abstract: The work mainly focused on a validation of the method for determining the content of salicylic acid and individual unknown impurities in new pharmaceutical product-tablets containing: 75, 100 or 150 mg of acetylsalicylic acid and glycine in the amount of 40 mg for each dosage. The separation of the components was carried out by means of HPLC, using a Waters Symmetry C18 column (4.6 × 250 mm, 5 μm) as the stationary phase. The mobile phase consisted of a mixture of 85% orthophosphoric acid, acetonitrile and purified water (2:400:600 V/V/V). Detection was carried out at a wavelength of 237 nm, with a constant flow rate of 1.0 ml min-1. In order to verify the method, linearity, precision (repeatability and reproducibility), accuracy, specificity, range, robustness, system precision, stability of the test and standard solution, limit of quantification and forced degradation were determined. Validation tests were performed in accordance with ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) guidelines. The method was validated successfully. It was confirmed that the method in a tested range of 0.005-0.40% salicylic acid with respect to acetylsalicylic acid content is linear, precise and accurate.