Browsing by Author "Wang, Chu-Fang"

Now showing 1 - 2 of 2

Profiling vertical distribution of scalants in RO membranes by LA-ICP-MS and fouling models
(2014-11-05)
Lin, Justin Chun-Te
;
Wang, Tsinghai
;
Ku, Yu-Hsuan
;
Hsieh, Yi-Kong
;
Wang, Chu-Fang
The vertical distribution of scalants as a result of 24 h of filtration of simulated low-level radioactive liquid waste in the reverse osmosis (RO) membranes was characterized by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Our results suggested that the development of scalants is associated with the formation of metal hydroxide colloids, while these colloids might penetrate relatively deeper into the membrane under the acid environment than under the alkaline environment. Fitting with a two-phase fouling Hermia\'s model suggested that the development of cake-like scalants in the first 5 h under alkaline environment is responsible for hindering the assess of metal hydroxides into the membrane so that they would not penetrate as deep as they do under the acid environment. (C) 2014 Elsevier B.V. All rights reserved.
Visualization of clogs developed from interaction between APDC and low-level radwaste relevant nuclides on RO membranes: A LA-ICP-MS study
(2014-04-15)
Chen, Lian-Song
;
Wang, TsingHai
;
Hsieh, Yi-Kong
;
Hsu, Chien-Hua
;
Lin, Justin Chun-Te
In this study, we used LA-ICP-MS to visualize the fouling induced by seeded filtration for efficient removing liquid low-level radwaste relevant nuclides using a reverse osmosis (RO) membrane. Evidenced by a significant permeate flux drop, these APDC additives pronouncedly increased the rejection by around 20% (from 68% to 84%) for cobalt, 30% for strontium (from 55% to 71%), and 70% for cesium (from 20% to 34%). Surface mapping using LA-ICP-MS showed that the hot zones of Co, Sr, and Cs in the APDC-Co, APDC-Sr and APDC-Cs systems were perfectly superimposed with the locations of the S moiety of APDC. This suggested that the improved rejection is closely related to the formation of APDC-metal complexes, and the possible coprecipitation of these elements with APDC-metal complexes. Further depth profile analyses revealed that the fouling mainly occurred in the first 2-6 pm of the RO membrane. Fitted with the Hermia model, it was evident that APDC additives facilitate the formation of complete blocking, intermediate blocking, and standard blocking, and as a consequence enhance Co rejection. By contrast, cake formation induced by APDC additives was mainly responsible for the better rejection of Sr and Cs. Importantly, our depth profile analyses undoubtedly suggested that a large particle/colloid is able to penetrate deeply into the membrane despite its pore size is much smaller than those particles/colloids. (C) 2014 Elsevier B.V. All rights reserved.