Nitrate determination in natural waters by spectral photometry with a miniaturized fiber-coupled flow cell

This paper presents the formulation of an integrated Back Flow Cell Model (IBFCM) for ozonation processes by incorporating together the contactor hydrodynamics, mass transfer, ozone decay in water, microbial inactivation, and disinfection by-products formation to describe the significance of their interrelated nature in determining the overall process performance. It also summarizes the experimental procedures that could be used to quantify the characteristic parameters for each process component. The model applicability was then illustrated by comparing the predictions with the experimentally observed dissolved ozone profiles. Further analysis was made to demonstrate the model application for predicting the disinfection efficiency and disinfection by-products formation simultaneously. From these analyses, it was also found that during the ozonation of natural waters, the ozone decay could not be described by the simple first order rate expression.

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Development of an In Situ Analyzer Based on Sequential Injection Analysis and Liquid Waveguide Capillary Flow Cell for the Determination of Dissolved Reactive Phosphorus in Natural Waters

Sensors ◽

10.3390/s20102967 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2967

Author(s):

Zeming Yang ◽

Cai Li ◽

Zhenzhao Zhang ◽

Guixin Lu ◽

Zifeng Cai ◽

...

Keyword(s):

Natural Waters ◽

Capillary Flow ◽

Northern South China Sea ◽

River Estuary ◽

Chemical Separation ◽

Flow Cell ◽

Injection System ◽

Sequential Injection Analysis ◽

Sequential Injection

This study presents an innovative technique for the in situ analysis of aquatic biochemical elements detected through wet chemical processes. A new compact in situ phosphate analyzer based on sequential injection analysis, liquid waveguide capillary flow cell and spectrophotometry was developed, and a safe and modular electronics-chemical separation mechanical structure was designed. The sequential injection system of this analyzer was optimized, and the major functions of this analyzer were studied and estimated. With a 10 cm liquid waveguide capillary flow cell and a 6.3 min time cost of detection, the analyzer reaches a detection limit of 1.4 μg·L−1 (≈14.7 nM, [PO43−]) and a consumption of 23 μL at most for each reagent. This analyzer was operated in situ and online during two scientific research cruises in the Pearl River Estuary and northern South China Sea. The advantages of this analyzer include its simple versatile manifold, full automation, low chemical consumption and electronics-chemical separate safe structure. Long-term in situ performance of this analyzer will be validated in the future.

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