Papers by Keyword: pH

Abstract: The gold nanoparticles were successfully synthesized using the chemical reduction method. The surface of gold nanoparticles was modified using three different charges of amino acid. The amino acid that used in this study was cysteine, arginine, and glutamic acid. The calcium and phosphate sources were added to amino acid capped gold nanoparticle solution to obtain hydroxyapatite. Hydroxyapatite is an inorganic material for teeth and bone tissue engineering. The morphological properties of the samples were investigated using Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FE-SEM). Different morphological characteristic was seen in different pH synthesis. The pH variation was normal pH that form in the solution and pH adjusted to 10 using NaOH in the hydroxyapatite formation. The elemental composition was also investigated using Energy-Dispersive X-ray (EDS) analysis. The elemental mapping was shown the homogeneity composition distribution of Ca and P on the sample pH adjustment that contains cysteine. The EDS results indicate the adjusted pH to 10 was potentially formed hydroxyapatite with a Ca/P ratio close to the theory.

Abstract: The paper analyzes the impact of personal protective equipment used by the population as a result of the COVID-19 pandemic on the environment. The scale of the additional amount of waste generated as a result of the use of protective face masks, etc. is noted. The globality of the existing problem and its multiparametric impact on the components of the environment are indicated. The short-term effect of a number of disposable protective face masks on the condition of soil by chemical component has been studied. The dependence of leaching of heavy metals from masks on soil acidity was experimentally analyzed, the dynamics of mobile phosphorus and potassium in soil samples was studied. It is shown that the presence of masks in the soil leads to exceeding the standard for zinc content, while for copper content and manganese content exceeding the standard is not observed in the study period, for lead there are fluctuations in content beyond standard value. The need for long-term research on the impact of face masks on the environment, and in particular soils, was noted.

Abstract: Sub-Sahara Africa countries are faced with the problem of solid waste management and access to sustainable energy. There is a need to develop a technology that can help to manage the generated solid waste and the same time produce green energy that is sustainable. Hence, this research work that focused on the development of a novel three-stage anaerobic digestion (AD) plant for management of biodegradable portion of municipal solid waste. An experimental design and preliminary tests using co-digestion of municipal solid waste was conducted with the operation and process parameters utilized in this research work. Conceptual design was generated based on results of experimental design. The developed AD plant was evaluated for performance and the results obtained compared to an existing single stage fixed dome AD pilot plant using 100 kg of substrates with an organic loading rate of 3 kg/m³day for an operating time of 163 days. The cumulative biogas yield, and behaviour of the operation and process parameters utilized in this research work were evaluated. The results obtained reveal that unlike the single stage fixed dome AD pilot plant, the three-stage AD plant enables continuous production of biogas. Besides, optimum conditions of neutral pH range of 6.99 m to 7.01 m, slurry mesophilic temperature range of 37.05 °C to 37.15 °C, and organic loading rate of 3kg/m³d that favoured optimum biogas yield were established.

Abstract: Microorganisms can initiate, accelerate, and/or inhibit corrosion processes through several different ways, including modification of the localized environment at the metal/solution interface causing pitting attack. In this work, the effect of pH on Pseudomonas growth was investigated in understanding the biodeterioration manganese steel rod due to bacteria attack. This study focused on identifying the effect of pH on the corrosion of galvanized steel. In artificial seawater containing Pseudomonas Aeruginosa. Galvanized steels were exposed to the medium for 7 days at 37°C at pH ranging from 5.0 to 9.0. Roles of different metallurgical, chemical and microbiological features on the surface will be reviewed to interpret this phenomenon. The results confirmed that the pits formed in this case are attributed to the Pseudomonas Aeruginosa sp under microbial corrosion.

Abstract: Gold nanoparticles (AuNPs) have received considerable attention recently because of their chemical properties and potential applications in the medical field.Monodispersed AuNPs in this paper are successfully synthesized by using some stabilized ligands including 3,5-dinitrobenzoic acid (DNBA) and sodium acetate (SA) dispersible in aqueous media, where NaBH₄ was used as a reducing agent to reduce KAuCl₄ from Au (III) to Au (0).The synthesized AuNPs are characterized by using UV–Vis spectroscopy to evaluate their surface plasmon resonance (SPR) absorption in a wavelength range of 500–650 nm. The size and morphology of AuNPs were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), where the results displayed that AuNPs with a strong SPR peak around 530 nm and 536 nm with an average size of 10 ± 1.2 nm and 14.0 ± 0.9 nm at the initial time for both DNBA-AuNP and SA-AuNP respectively. The synthesized AuNPs illustrate perfect chemical stability for more than 24 weeks in an aqueous solution. Therefore, the size of DNBA-AuNP was smaller and most stable than SA-AuNP, which may be due to 2 nitro groups that have resonance with the benzene ring leading to an increase in the stability of AuNPs.The stability of AuNPs in this work was monitored at a range of pH 2-12. Where high stability was showed at pH 6.6 ± 0.5, while the aggregation appears at more than pH 10 and less than pH.3.5.Herein, in this paper AuNPs have shown remarkable results against multi-drug resistance Pseudomonas aeruginosa. AuNP functionalized by SA ligand is shown to have a greater biological effect and be more effective than DNBA-AuNP. Due to the high stability of AuNP prepared in this work, it can be further tested to be an improved choice for more biomedical applications in the future.

Abstract: Nanoparticle has been used in agricultural practices such as soil ameliorant. Nanoparticle of volcanic ash and biofertilizer were applied to improve some soil characteristics of Inceptisols. The objective of this research was to optimize the benefit of nanoparticle of volcanic ash and biofertilizer in reducing soil acidity, increasing organic carbon content, and increasing basic cations of Inceptisols. Volcanic ash was obtained from the eruption of Mt. Merapi in Central Java. Nanoparticle was grinded in Nanotechnology and Graphene Research Center, Universitas Padjadjaran. Phosphate solubilizing fungi was used as biofertilizer, isolated in Soil Microbiology Laboratory, Universitas Padjadjaran. A two factors randomized experimental design was used in this research. Nanoparticle of volcanic ash was used as first factor (four levels: 0%, 2%, 4% and 6% of soil weight percentages). Biofertilizer was used as second factor (two levels: 0 and 10 g.kg^-1). These two treatments were combined and mixed evenly and incubated for three months in field condition. Every month during those three months a few soil samples were taken to analyze the change of soil characteristics. The results showed that the treatments increased organic carbon content and potassium basic cation but had no effect to soil acidity.

Abstract: Silver nanoparticles (AgNPs) have become interesting metal nanoparticles for filler composite electroactive bone scaffold due to its favorable electrical conductivity, chemical stability, and antibacterial activity. The green synthesis method was selected to produce AgNPs because of using safer solvents, minimizing dangerous reagents, and providing benign response conditions suitable for medical applications. In this study, AgNPs were prepared by a green synthesis approach using Indonesian wild honey with a wider pH range (5, 8, 11). Based on visual observation, UV-Vis spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) data, increasing pH leads to faster formation of AgNPs and smaller particle size of AgNPs. It was found that the smallest particle size of AgNPs (hydrodynamic diameter is 46.5 nm from DLS result and the actual particle size is 6.3 ± 1.5 nm from TEM result) was generated at pH 11.

Abstract: Adding sap particle, Portland cement foamed concrete was studied to manufacture a new type of planting material. The pH, porosity, permeable capacity, infiltration rate and water storage were tested for evaluating the performance of foamed concrete. Solid-liquid extraction method and image binaryzation were used to study the pH and porosity of foamed concrete. A kind of self-made permeable device was also used in this paper. It was found that the pH of foamed concrete could be decreased by sap particles absorbed the boric acid solution in 14 d. For the foaming effect of fresh concrete was disturbed by liquid from sap particles, the porosity of foamed concrete was increased and then decreased. Seepage channels could be formed in foamed concrete when sap particles shrunk for releasing liquid and they also would be block for sap particles expanding when water permeated into foamed concrete. The permeable capacity and infiltration rate were decreased with increasing sap particles. The water storage of foamed concrete was fluctuated with sap particles increasing but more than that without sap particles. The optimal dosage of sap particles was 0.3wt% of binder material in this study. At the dosage, the minimal pH of foamed concrete could be obtained and performance of that would be good to plant, such as permeable capacity, infiltration rate and water storage.

Abstract: Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H₂SO₄) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, E_g of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.

Abstract: Bio-Dye is a dye derived from natural ingredients that have an important role in DSSC performance. This Bio-Dye is later in charge of absorbing sunlight entering the DSSC cells. Bio-Dye is a dye derived from natural ingredients that have an important role in the performance of the DSSC. This Bio-Dye is the one that will be in charge of absorbing sunlight entering the DSSC cells). One important key to know DSSC performance is to pay attention to the quality of the BIO-Dye. A good BIO-Dye can be seen by knowing the absorbance pattern and the function group of the dye its self. This research was conducted to determine absorbance patterns and functional groups based on pH variations in the wet and dry extraction methods contained in the Ocimum sanctum. The absorbance pattern was seen using a UV-Vis spectrophotometer and a functional group using FTIR. The chlorophyll pigment contained in the BIO-Dye (Ocimum sanctum leaf) was extracted using an ethanol solvent and added acetic acid to produce variations in pH values. The UV-Vis spectrometer measurement results showed the highest absorbance pattern was possessed by Ocimum sanctum dye in the dry extraction method and at natural pH (pH = 6.5). The peak absorbance they have is 648 nm, 614 nm, and 537 nm. The FTIR spectrum was obtained from Ocimum sanctum information containing the same functional groups when variations in pH values ​​were carried out in the wet and dry extraction methods. The functional groups are OH groups at wave number 3356.57 cm^-1, CH at 2975.37 cm^-1, C = O at 1652.50 cm^-1, CN at 1383.81 cm^-1, C = C at 880.25 cm^-1, and CH absorbed at wave number 1087.78 cm^-1. In general, it can be concluded that natural dye from Ocimum sanctum has a high absorbance in the visible light region and contains COOH compounds that can strengthen the bond of dye with TiO₂ semiconductors so that Ocimum sanctum can be used as a dye in Dye-Sensitized Solar Cells (DSSC).