Osmotic Membrane Distillation Crystallization of NaHCO3

Abstract

A new crystallization process for sodium bicarbonate (NaHCO3) was studied, proposing the use of osmotic membrane distillation crystallization. Crystallization takes place due to the saturation of the feed solution after water evaporation on the feed side, permeating through the membrane pores to the osmotic side. The process operational parameters, i.e., feed and osmotic velocities, feed concentration, and temperature were studied to determine the optimal operating conditions. Regarding the feed and osmotic velocities, values of 0.038 and 0.0101 m/s, respectively, showed the highest transmembrane flux, i.e., 4.4 × 10−8 m3/m2·s. Moreover, study of the temperature variation illustrated that higher temperatures have a positive effect on the size and purity of the obtained crystals. The purity of the crystals obtained varied from 96.4 to 100% In addition, the flux changed from 2 × 10−8 to 7 × 10−8 m3/m2·s with an increase in temperature from 15 to 40 °C. However, due to heat exchange between the feed and the osmotic solutions, the energy loss in osmotic membrane distillation crystallization is higher at higher temperatures.

Fluoride Removal and Recovery from Water Using Reverse Osmosis and Osmotic Membrane Crystallization

“…When the feed concentrations are lower, the water activity and driving force are higher, whereas higher osmotic concentrations result in lower water activity and higher driving force [26,42]. Consequently, an increase in feed concentration is expected to lead to a decrease in flux.…”

“…The researchers highlighted OMD as an innovative technology that serves as an alternative to traditional crystallizers. This is attributed to its various advantages, including reduced energy and material consumption, enhanced control over operational parameters, and a larger evaporation surface area, among other benefits [42].…”

Key Parameters Impacting the Crystal Formation in Antisolvent Membrane-Assisted Crystallization

“…Membranes have been serving us well in different sectors such as water purification, gas separation and CO 2 capture [ 1 , 2 , 3 , 4 ], but novel applications are emerging nowadays. Membrane-assisted antisolvent crystallization (MAAC) is a new technique to control antisolvent crystallization.…”