Influence of Temperature on the Performance of Forward Osmosis Using Ammonium Bicarbonate as Draw Solute

Liyuan Feng,Lixin Xie,Xiaofeng Shao,Tao Dong,Gaofeng Suo

doi:10.1007/s12209-018-0159-1

Abstract

This study investigated the influence of temperature on the performance of forward osmosis (FO) under the condition that the feed solution (FS) temperature was different from draw solution (DS) temperature. An FO model considering the mass and heat transfer between FS and DS was developed, and the FO experiment with ammonium bicarbonate solution as DS and sodium chloride solution as FS was carried out. The predicted water flux and reverse draw solute flux using the developed model coincided with the experimental fluxes. Increases in the temperature of FS or DS yield corresponding increases in the water flux, reverse draw solute flux, and forward rejection of feed solute. Compared with increasing the FS temperature, increasing the DS temperature has a more significant impact on enhancing FO performance. When the temperature of DS increased from 20 to 40 °C, the specific reverse solute flux decreased from 0.231 to 0.190 mol/L.

Highlights

Seawater desalination is considered to be one of the most attractive technologies for alleviating water scarcity [1]
The slopes of these fitting lines represent values of water permeation coefficient at different temperature gradients, and the result indicates that the water permeation coefficient increases with an increase in the feed solution (FS) or draw solution (DS) temperature, which is consistent with previous research [29]
The water viscosity was lower and the water diffusion coefficient was larger at higher temperature, causing a larger water flux

Summary

Introduction

Seawater desalination is considered to be one of the most attractive technologies for alleviating water scarcity [1]. Like the majority of pressure-driven membrane processes [16], feed solutes are retained on the active layer surface as water molecules flow to DS, which causes CECP. The reverse draw solute flux inside the support layer under steady-state conditions can be written as follows [12]: Js. where DDe port layer, is the effective diffusion coefficient of and is proportional to DD5 by DDe =. (14) where Q represents the heat flux (W/m2); h is the heat transfer coefficient (W/(m2 K)); M is the molar mass (g/mol); cρ is the specific heat (J/(kg K)); and the subscripts w, a, and s refer to water, the active layer and support layer of FO membrane, respectively. To ensure the accuracy of results, each experiment was repeated three times

Evaluation of FO Performance

Results and Discussion

Conclusion