Characterization of degradation products of activated diethanolamine and methyldiethanolamine during carbon dioxide absorption and desorption processes / Md. Sakinul Islam

Degradation studies of activated Diethanolamine (DEA) and Methyldiethanolamine (MDEA) induced by carbon dioxide were conducted in jacketed glass reactor under absorber and stripper conditions at atmospheric pressure. Piperazine (PZ) is used as an activator in this system. There are eighteen amines and activated amine samples studied. Pure carbon dioxide was bubbled through the reactor till saturation. The concentration of amine and activator used ranging from 2M to 4M and 1M to 2M respectively. On the other hand activated amine concentrations ranged from 4M to 11M. Six generic cycles were conducted for each run during the degradation experiments. Each cycle configured with the absorption and desorption of carbon dioxide at 55 ˚C and 100 ˚C respectively. Samples were collected after a predetermined experimental time and analyzed by various chromatographic methods to identify degradation products. The degradation products were identified using ion chromatography (IC), high performance liquid chromatography (HPLC)-UV detection and gas chromatography mass spectroscopy (GC/MS). In the IC analysis three different columns were used for Anion, Cation and Ion exclusion systems these are Metrosep A Supp 5 150/4.0, Metrosep C Supp 4 150/4.0 and Metrosep Organic Acids respectively. The supelco HPLC column was used to identify polar degradation products of amine sample. In the GC-MS chromatographic analysis HPINNOWAX (30 m × 0.250 mm × 0.25μm) column was used. The major identified degradation products in IC analysis are nitrate, nitrite, acetate, phosphate and ammonium. In HPLC analysis the most common degradation products are found formamide, 2-(2- aminoethoxy)ethanol, Diethylenetriamine, Ethyl 1-piperazinecarboxylate, N-(2-Hydroxyethyl) ethylenediamine, Triethanolamine, 2-Methoxyethanol, Ethylene glycol, 1,4- Dimethylpiperazine and 1-(2-Aminoethyl) piperazine. GC-MS is particularly conducted for five alkanolamine samples which are DO2PZ2M, D05DEA4M, D10DEA7MPZ2M, D13MDEA4M and D18MDEA7MPZ2M. Five degradation products are identified for DO2PZ2M and these are Formamide, Ethylenediamine, N-formylpiperazine, Fomic acid and Imidazole. D05DEA4M degraded sample shows ten degradation products these are Formamide, N-(hydroxyethy1) ethylenediamine, Oxazolidone, 2-(2-aminoethoxy) ethanol, 2- amino-2-methyl-1-propanol, N,N-bis(hydroxyethy1)- ethylenediamine, Ethylurea, 2- methylaminoethanol, ethanol and acetone. Activated DEA sample D10DEA7MPZ2M shows twelve DGPs these are Formamide, 1,4-Bis(2-hydroxyethyl)piperazine, Oxazolidone, 1,4- Dimethylpiperazine, N,N-bis(hydroxyethy1)ethylenediamine, 2-dimethylaminoethanol, 1-(2- Aminoethyl)piperazine, Ethyl-1-piperazinecarboxylate, Acetic acid, Glycolic acid, Ethyl urea and Acetone. Inactivated MDEA samples D13MDEA4M was analyzed and eleven degradation products are found which are 1, 4-Bis (2-hydroxyethyl)-piperazine, Bis-(2-hydroxypropyl) amine, Oxazolidone, 2-(2-aminoethoxy)ethanol, 2-Amino-2-methyl-1-propanol, 2- dimethylaminoethanol, Ethylurea, Glycolic acid, Acetaldehyde, Ethanol and Acetic acid. Similarly eight degradation products are found for D18MDEA7MPZ2M sample which are 1- Methyl piperazine, 1, 4-Bis(2-hydroxyethyl)piperazine, Bis(2-hydroxypropyl) amine, N, Ndimethyl piperazine, 2-Amino-2-methyl-1-propanol, 2-dimethylaminoethanol, 1-(2- aminoethyl) piperazine and ethanol. In addition two physical properties density and viscosity of eighteen activated and inactivated amine samples are measured at 30 ˚C, 55 ˚C and 100 ˚C and it was found that the both physical properties decreased with increasing temperature. However, in case of increasing concentration it is significantly increases the density and viscosity of both activated and inactivated amine solutions. Keywords: Degradation, activated diethanolamine, activated methyldiethanolamine, absorption, stripping, desorption

Trace metals concentration in vegetables of a sub-urban industrial area of Bangladesh and associated health risk assessment

Trace metals contamination of vegetables in the sub-urban industrial area of Bangladsh are increasing day by day. The mostly consumed vegetables like tomato (Lycopersicon lycopersicum), spinach (Spinacea oleracea), bean (Lablab purpureus), brinjal (Solanum melongena), potato (Solanum tuberosum), cauliflower (Brassica oleracea var botrytis), cabbage (Brassica oleracea var cupitata), and radish (Raphanus sativus) were collected from industrial area. Trace metals arsenic (As), manganese (Mn), zinc (Zn), cadmium (Cd) and lead (Pb) were measured using atomic absorption spectrophotometer (AAS). The descending order of trace metals followed the order of Zn>Mn>Pb>Cd>As. The results revealed that every vegetable contained the highest concentration of Zn range from 15 ± 1.4 to 50 ± 4.0 mg/kg fresh weight. Trace metals in vegetables exceeded the permissible level of FAO and WHO standard. The non-carcinogenic and carcinogenic risks were estimated on the basis of estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and target carcinogenic risks (TRs). The EDI values of all trace metals were below the maximum tolerable daily intake (MTDI). Total target hazard quotient (TTHQ) were greater than 1, indicated that if people consume these types of vegetables in their diet, they might pose risk to these metals. Finally, the total cancer risks (TRs) values were 6.4 × 10−3 for As and 8.7 × 10−5 for Pb which were greater than threshold value of USEPA (10−6), indicating that the consuming inhabitants of these vegetables are exposed to As and Pb with a lifetime cancer risk

Grafting of acrylonitrile monomer onto bleached okra bast fibre and its textile properties

321-327 The graft copolymerization of acrylonitrile monomer onto okra bast fibre has been carried out using potassium persulphate as an initiator in the presence of ferrous sulphate. The graft yield is evaluated on varying the concentration of monomer from 1.0×10-2 to 7.0×10-2 mol L-1 and concentration of potassium persulphate from 1.0×10-3 to 7.0×10-3 mol L-1 at ferrous sulphate concentration varying from 1.0×10-3 to 7.0×10-3 mol L-1 in the reaction mixture. The graft yield and other grafting parameters have been optimized at 3.0×10-2 mol L-1 monomer, 4.0×10-3 mol L-1 potassium persulphate, 5.0×10-3 mol L-1 ferrous sulfate, 120 min treatment time and 70°C temperature. The composition of grafted chain is characterized by Fourier transform infrared spectra and scanning electron microscopic studies. Dyeing and tensile properties of grafted okra bast fibre have also been studied. The grafted fibre shows better properties in all cases in comparison to bleached okra bast fibre. </smarttagtype