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Flow Injection Stripping Potentiometry with Periodic Alternation of Flow Direction
Chow, Christoper W.K.,Kolev, Spas D.,Davey, David E. 경북대학교 센서기술연구소 1994 센서技術學術大會論文集 Vol.5 No.1
A fully computerized flow injection (FI) manifold with a peristaltic pump allowing periodic alternation of the flow direction and incorporating a detector system capable of performing potentiometric stripping analysis (PSA) is outlined. The proposed measuring technique combines the attractive features of both traditional flow injection analysis (FIA) and batch PSA and at the same time overcomes some of the most serious drawbacks of the latter resulting from the fact that potentiostatic deposition and chemical stripping occur in the same solution. An experimental study of the influence of the main parameters of the flow system on its behaviour was performed using Cu(II) solutions in the parts per billion concentration range as samples. The potentiostatic deposition was carried out on a precoated Hg glassy carbon electrode while Hg(II) ions were utilized as oxidant in the chemical stripping step. The magnitude of the analytical signal is independent of the electrode area which allows miniaturization of the equipment. The results obtained suggest that the proposed technique could be implemented in compact, inexpensive and fully automated flow-through systems for quantitative determination of low concentration metals ions in various samples (e.g., heavy metals in environmental, food and pharmaceutical samples).
Byeongcheol Min,Surya N. Jampana,Christoper M. Thomas,Bandaru V. Ramarao 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.2
Buffer substitution method were studied to improve the efficiency and to reduce cost of enzymatic hydrolysis of paper mill waste fines. The method is utilization of CaCO₃ in waste fine as a buffer material to substitute traditional buffer chemicals using in hydrolysis process. The 0.05M of sodium acetate buffer required 8.2 ㎏ of sodium acetate and 2.0 ㎏ of acetic acid per 100 ㎏ of waste fines to make the pH 5. When buffer solution and waste fines were mixed, the pH of the mixture shifted to 6.5-7.0 due to the dissociation of CaCO₃. The shifted pH was adjusted with addition of extra acids such as sulfuric acid and acetic acid to reach the pH to 5.2. Adjustment of pH increased waste fine hydrolysis yield from 33.7% to 41.4% by addition of extra acetic acid as much as 6.3 ㎏ per 100 kg of waste fines. For the buffer substitution method, only 7.7 ㎏ of acetic acid was demanded without sodium acetate for the same pH level (pH 5.2) of the mixture. The buffer substitution method resulted in 40.8% of hydrolysis yield which was comparable result of pH adjustment of buffer. The buffer substitution method reduced the requirement of 8.2 ㎏ of sodium acetate and 0.6 ㎏ of acetic acid for 100 ㎏ of waste fine hydrolysis. Addition of sulfuric acid resulted adverse effects compared to addition of acetic acid for both pH adjustment and buffer substitution.