Adsorption efficiency of natural materials for low-concentration cesium in solution

Abstract

In this study, several natural materials were investigated in order to clarify their potential use as cesium (Cs) adsorbents in situ. Four materials--carbonized rice hull, beech sawdust, oak sawdust, and charcoal (Japanese cedar)--which were previously shown to have Cs adsorption capabilities, were examined. Cs adsorption experiments were conducted using different initial Cs and adsorbent concentrations. The physical properties, adsorption isotherms, and adsorption processes were then examined, so as to exploit the Cs adsorption characteristics in the field. Based on these findings, carbonized rice hull and beech sawdust were selected as effective Cs adsorbents. It was found that these materials show continuous and stable Cs adsorption rates for different initial Cs concentrations. The adsorption efficiency of these two adsorption materials in combination was considered, and it was shown that the adsorption isotherms for carbonized rice hull and beech sawdust follow the Freundlich model. Furthermore, the beech sawdust adsorption process exhibited better agreement with the calculated values obtained via the adsorption rate model and the adsorption kinetics model than did the carbonized rice hull adsorption.

Determination of Cesium Adsorption Breakthrough Curves Using Carbonized Rice Hull and Beech Sawdust as Adsorbents

“…This result for beech sawdust is similar to that obtained in our previous adsorption experiments using the batch method [7], where an adsorption rate of 45% was obtained. However, the adsorption ratio for carbonized rice hull obtained using the batch method was ~90%, which is significantly greater than that obtained in this study.…”

“…Carbonized rice hull (commercially available) and beech 462 Determination of Cesium Adsorption Breakthrough Curves Using Carbonized Rice Hull and Beech Sawdust as Adsorbents sawdust (from the Yamagata prefecture) were selected as the natural materials of interest based on their previous identification as candidate materials for Cs adsorption [7]. The physical properties of these materials were reported in our previous study [7].…”

“…The physical properties of these materials were reported in our previous study [7]. Minimal screening was carried out on the carbonized rice hull and beech sawdust samples to minimize the number of steps required during their potential utilization in the field.…”

“…Carbonized rice hull gave a solution pH of 7.25, while beech sawdust gave a pH of 6.42. Prior to carrying out any further experiments, each material was pretreated using a previously described procedure [7].…”

“…To address such issues, the author previously examined the potential of natural materials, which are readily available in agricultural areas, for use as Cs adsorbents in mountain streams and reservoirs [7]. More specifically, the examination of five different natural materials indicated that carbonized rice hull and beech sawdust were the most promising adsorbents, and batch adsorption experiments revealed that the adsorption isotherms of these two natural materials fitted well with the Freundlich adsorption isotherm.…”