Antonius Indarto

Nanotechnologies in water and air pollution treatment

The issue of environmental pollution has become a hot issue in todays world. Environmental pollution, mainly caused by toxic chemicals, includes air, water, and soil pollution. This pollution results not only in the destruction of biodiversity, but also the degradation of human health. Pollution levels that are increasing day by day need better developments or technological discoveries immediately. Nanotechnology offers many advantages to improve existing environmental technologies and create new technology that is better than current technology. In this sense, nanotechnology has three main capabilities that can be applied in the fields of environment, including the cleanup (remediation) and purification, the detection of contaminants (sensing and detection), and the pollution prevention.

Polycyclic aromatic hydrocarbon formation mechanism in the “particle phase”. A theoretical study

The synthesis of polycyclic aromatic hydrocarbons (PAHs) and the formation of soot platelets occur both during combustion at relatively low [O(2)], or under pyrolysis conditions. When the PAH size grows beyond the number of three-four condensed cycles, the partitioning of PAHs between the gas and particle phases favours the latter (i.e. adsorption). This study aims to assess which role the soot particle plays during PAH synthesis, in particular if catalytic or template effects of some sort can be exerted by the soot platelet on the adsorbed growing PAH-like radical. Our theoretical calculations indicate that chain elongation by ethyne addition cannot compete with cyclization when both can take place in the growing PAH-like radical, already in the gas phase. When it is adsorbed, cyclization is found to become easier than in the gas phase (more so, in terms of Gibbs free energy barriers, at higher temperatures), hinting at some sort of template effect, while chain elongation by ethyne addition becomes somewhat more difficult. The underlying soot platelet can assist (at lower temperatures) the formation of a larger aromatic hydrocarbon, by a final hydrogen abstraction from that endocyclic saturated carbon the newly formed cycle still bears. As an alternative (at higher temperature), a spontaneous hydrogen atom loss can take place. Finally, at rather low temperatures, the addition of the growing radical to the underlying soot platelet might occur and cause some reticulation, form more disordered structures, i.e. soot precursors instead of PAHs.

Heterogeneous reactions of HONO formation from NO2 and HNO3: a review

The photolysis of nitrous acid (HONO) is an important reaction of atmospheric chemistry due to the fact that it can be the source of OH radical in the troposphere. Despite its role as a radical precursor, the chemical mechanisms leading to HONO formation are not well understood. It is commonly assumed that HONO formation is due to both homogeneous and heterogeneous processes involving NOx (mixture of NO and NO2) in which the kinetic and mechanistic details are still under investigation. In this discussion, we would like to highlight the formation of HONO from NO2 and nitric acid (HNO3) in the presence of organic particulate. We understood that in the real case, many parameters can influence the reaction mechanism; however, this is just an effort to have a better understanding of the study of HONO formation in the atmospheric process.

H2S–CO2 Separation Using Room Temperature Ionic Liquid [BMIM][Br]

Solubility and selective absorption of hydrogen sulfide (H2S) over carbon dioxide (CO2) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) has been evaluated under ambient temperature and pressure. [BMIM][Br] demonstrated its potential as a solvent for selective removal of H2S from CO2/H2S mixture. Our investigation indicated that H2S solubility in [BMIM][Br] is comparable to or better than that in commercially available MDEA-based solvents. Meanwhile, CO2 solubility in [BMIM][Br] is lower than that in the same amine resulting in H2S/CO2 absorption selectivity of within 3.5 to 3.75. The solubility behavior is relatively maintained after 4 times absorption-desorption cycles. A computational molecular study suggested that intramolecular hydrogen bonding interaction between anion Br and hydrogen atom of H2S could stabilize the complex and resulted lower complexation energy than CO2 interaction with [BMIM][Br]. Based on the experiment results, a separation process employing [BMIM][Br] is proposed to control the CO2/H2S ratio existing in a natural gas feed.

Decomposition of dichlorobenzene in a dielectric barrier discharge

This paper presents a decomposition study of 1,2-dichlorobenzene (DCB) using a dielectric barrier discharge (DBD). The discussion is focused on the effects of variations of carrier gases, DCB concentrations and input voltages on the decomposition performance. The DCB conversion was conducted inside a cylindrical reactor consists of silver film as the outside electrode and a spring coil as the inside electrode. Two carrier gases, i.e. air and nitrogen, were introduced to the reactor at a total flow rate of 500 mL/min with DCB concentrations of 100, 300 and 500 ppm. Gaseous products, before and after plasma treatment, were analysed by a gas chromatography and FT-IR spectroscopy, and the consumed power was calculated from Lissajous’ figure analysis. In order to improve the decomposition performance, various TiO2-supported catalysts were employed.

Methanol Synthesis Over Cu and Cu-Oxide-Containing

Initially developed for more than 20 years ago, the copper over zinc and aluminum oxide (ZnO/Al2O3) catalyst system is used for low-pressure methanol synthesis. Recently, the Cu/ZnO/Al2O3 (CZA) was shown to be active in a dielectric-barrier discharge (low-temperature plasma). In this paper, the investigation on the copper as the active site of the catalyst was discussed on the basis of experimental results and its characterization analysis. The catalyst was attempted to aid the reaction performance of partial oxidation of methane in order to produce methanol. All CZA-based catalysts were successful in increasing methanol selectivity, and the Cu oxide performed better than a metallic-copper catalyst.

\hbox{ZnO}/\hbox{Al}_{2}\hbox{O}_{3}

Non-catalytic conversion of methane (CH4) and nitrogen dioxide (NO2) into methanol (CH3OH) has been conducted and presented in this paper. Experiments were carried out using dielectric barrier discharge as the reaction medium in atmospheric pressure and temperature conditions. High yield production of methanol was achieved (18–20% mol) by single-stage plasma reaction with maximum selectivity of 32% mol. Compared to other oxidants, such as O2, the presence of NO2 in the plasma reaction resulted in higher methanol selectivity. For better understanding of the reactions, density functional theory calculations were also performed and discussed.

Using Dielectric Barrier Discharge

Our purpose is to identify a computational level sufficiently dependable and affordable to assess trends in the interaction of a variety of radical or closed shell unsaturated hydro-carbons A adsorbed on soot platelet models B. These systems, of environmental interest, would unavoidably have rather large sizes, thus prompting to explore in this paper the performances of relatively low-level computational methods and compare them with higher-level reference results. To this end, the interaction of three complexes between non-polar species, vinyl radical, ethyne, or ethene (A) with benzene (B) is studied, since these species, involved themselves in growth processes of polycyclic aromatic hydrocarbons (PAHs) and soot particles, are small enough to allow high-level reference calculations of the interaction energy ΔEAB. Counterpoise-corrected interaction energies ΔEAB are used at all stages. (1) Density Functional Theory (DFT) unconstrained optimizations of the A-B complexes are carried out, using the B3LYP-D, ωB97X-D, and M06-2X functionals, with six basis sets: 6-31G(d), 6-311 (2d,p), and 6-311++G(3df,3pd); aug-cc-pVDZ and aug-cc-pVTZ; N07T. (2) Then, unconstrained optimizations by Møller-Plesset second order Perturbation Theory (MP2), with each basis set, allow subsequent single point Coupled Cluster Singles Doubles and perturbative estimate of the Triples energy computations with the same basis sets [CCSD(T)//MP2]. (3) Based on an additivity assumption of (i) the estimated MP2 energy at the complete basis set limit [EMP2/CBS] and (ii) the higher-order correlation energy effects in passing from MP2 to CCSD(T) at the aug-cc-pVTZ basis set, ΔECC-MP, a CCSD(T)/CBS estimate is obtained and taken as a computational energy reference. At DFT, variations in ΔEAB with basis set are not large for the title molecules, and the three functionals perform rather satisfactorily even with rather small basis sets [6-31G(d) and N07T], exhibiting deviation from the computational reference of less than 1 kcal mol(-1). The zero-point vibrational energy corrected estimates Δ(EAB+ZPE), obtained with the three functionals and the 6-31G(d) and N07T basis sets, are compared with experimental D0 measures, when available. In particular, this comparison is finally extended to the naphthalene and coronene dimers and to three π-π associations of different PAHs (R, made by 10, 16, or 24 C atoms) and P (80 C atoms).

Partial oxidation of methane to methanol with nitrogen dioxide in dielectric barrier discharge plasma: experimental and molecular modeling

The absorption of carbon dioxide (CO2) in phosphorous-based ionic liquids was studied theoretically by the molecular modeling ab initio density functional theory (dispersion-corrected B3LYP) and second-order Møller-Plesset perturbation methods. Several types of phosphate- and phosphite-based anions were employed and the calculation results were compared with recent published papers. The interaction energy between CO2 and anion, following the result of Bhargava and Balasubramanian, was calculated in order to have a better understanding on the effect of different functional groups on the interaction between CO2 and anion. The computational results indicated that the molar volume of the anion molecules played an important role on the absorption mechanism of CO2 due to the CO2-philicity of carbonyl and alkyl groups.

Density functional theory study of the interaction of vinyl radical, ethyne, and ethene with benzene, aimed to define an affordable computational level to investigate stability trends in large van der Waals complexes

This paper presents a direct comparison of the vibrational spectra between quantum mechanistic calculation and ultrashort laser pulses (USLP) spectrometer for chloroform oxidation. The chloroform decomposition was conducted in the presence of oxygen by using a gliding-arc plasma. In agreement with the prediction from both ab initio density functional theory calculation and USLP spectra analysis, it shows that the early step of the chloroform decomposition by oxygen follows a mechanism of CHCl3 + O2 rarr CCl3OOH rarr COCl2 + OH + Cl.