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A mathematical model was used to design four modes of two-bed pressure swing adsorption (PSA) process to investigate argon presence in the feed mixture. The effect of operating parameters such as cycle time, pressure equalization, adsorption pressure, and purging flow rate was investigated. The model was validated with experimental data of nitrogen separation from the air by a single bed adsorber on carbon molecular sieve (CMS). A good agreement with experimental data is obtained. In the PSA process, higher purity of nitrogen (99.7%) was detected by mode 4 when the feed mixture was free of argon (O2: 21%, N2:79%). While the nitrogen purity was only 98.0% in the state of argon presence in the feed mixture (O2: 21%, N2: 78%, Ar: 1%). The results showed that the cycle time had insignificant effect whereas the pressure equalization and purging at low vacuum pressure had a significant effect on the process performance. ABSTRAK: Model matematik digunakan bagi membina empat mod terdiri daripada tekanan dua-turus proses penyerapan buai (PSA) bagi menyiasat kehadiran argon dalam campuran pakan. Kesan parameter beroperasi seperti masa kitaran, penyamaan tekanan, tekanan penyerapan, dan kadar aliran penyingkiran disiasat. Model matematik tersebut disiasat melalui data eksperimen pemisahan nitrogen dari udara melalui penyerapan turus tunggal pada penapis molekular karbon (CMS). Data eksperimen yang bagus diperoleh. Dalam proses PSA, mod keempat menghasilkan ketulenan nitrogen (99.7%) lebih tinggi apabila campuran pakan bebas argon (O2: 21%, N2:79%). Sementara itu, ketulenan nitrogen hanya 98.0% apabila terdapat kehadiran argon dalam campuran pakan (O2: 21%, N2: 78%, Ar: 1%). Kajian menunjukkan masa kitaran memberi kesan tidak signifikan sementara penyamaan tekanan dan penyingkiran pada tekanan vakum rendah mempunyai kesan signifikan terhadap prestasi proses.

An investigation on two processes of pressure swing adsorption (PSA) to produce oxygen and nitrogen simultaneously was conducted numerically through exploiting depressurizing and purging gas of each process by each other. Each unit included two bed six step PSA process. The first unit packed with zeolite 13X for oxygen generation, and the second unit packed with carbon molecular sieve (CMS) for nitrogen generation. Three configurations were studied, two process were operated individually, depressurizing and purging gas of each process used by other unit ( no gas vented to atmosphere), and the third configuration was similar to the second configuration except purging gas of the second unit was vented to atmosphere. Configuration three produced oxygen with purity 98% and nitrogen with purity 95% together in comparing with configuration 1, and 2. Configuration 2 produced oxygen with purity over 99% while nitrogen purity dropped dramatically to be lower than its atmospheric purity (78%). Oxygen and nitrogen purity in all configuration improved with increasing the adsorption pressure.

In order to obtain a sufficient removal of heavy metal ions from water, new resources should be exploited to design more efficient and eco-friendly adsorbents. In this work, we have demonstrated an efficient, simple, and reusable adsorbent, which can be operated at the water treatment site. The simultaneous adsorption behavior and competitive interactions between As(III) and As(V) from aqueous solution onto chitosan/diatomaceous earth composite (CSD) were investigated at different solution-pH and adsorbent dosages. The adsorption mechanism was interpreted depending on the data of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. Results of batch equilibrium experiments indicated that the pH and adsorbent dosages have significantly influenced the adsorption process, and the adsorption of heavy metals was better fitted with Langmuir isotherm and pseudo-second-order models. The binary maximal adsorption capacities of As(III) and As(V), as determined from the Langmuir adsorption isotherms, were 87.81 mg/g and 44.07 mg/g at a pH of 6, respectively. The presence of phosphate (PO43−) as co-existing anions has an obvious impact on the adsorption of arsenic species. Based on the obtained results, the prepared adsorbent showed a great promise to be used in arsenic species adsorption from aqueous solution.