Comparative Performance of Tetraphosphonate and Diphosphonate as Reverse Osmosis Scale Inhibitors

Alexey Andrianov,Roman Efremov,Konstantinos D Demadis,Stefania Liakaki-Stavropoulou,Maria Danilycheva,A Volkov,A Pustovgar,A Adamtsevich

doi:10.1051/matecconf/201825103049

Abstract

Reverse osmosis (RO) technologies are widely used throughout the world for drinking, industrial and waste water treatment purposes. Proper and economically attractive operation of RO installations should be provided by the correct maintenance of all technical process parameters. One of the significant operational problems is precipitation and deposition of sparingly-soluble salts on the membrane surface, which can be prevented by dosing special chemical additives into the feed solution. The aim of the present work is to reveal the structure/function relationship of phosphonate scale inhibitors, which possess systematic structural similarities and differences. Specifically, two classes of tetraphosphonate (5 additives) and diphosphonate (6 additives) have been tested as calcium carbonate scale inhibitors on the lab membrane unit. It was found that among the family of tetraphosphonates and diphosphonates the inhibitor efficiency increases with elongation –(CH2)– chain, but the longest additives have a sharp drop in inhibition efficiency.

Highlights

Reverse osmosis is the predominant desalination technique for various applications
A wide number of chemical additives cab be applied for maintaining sustainable operation of reverse osmosis installations
The scale inhibition efficiency ranking was 2 < 4 < 6 < 8. These results reveal the tendency of decreasing of inhibition effect is proportional to the number of methylene groups on the side-chain

Summary

Introduction

Reverse osmosis is the predominant desalination technique for various applications. In spite of its efficiency, there are certain fundamental issues that cause operational problems. One of these is precipitation of sparingly-soluble salts on membrane surface, which changes the operating mode, deteriorates the product water quality and shortens the operating time of the membrane modules. Antiscalant dosing is one of the most widespread methods to prevent scaling. A wide number of chemical additives cab be applied for maintaining sustainable operation of reverse osmosis installations. The most widely accepted mechanistic scenario is that these chemicals stop or interfere with inorganic scale nucleation, precipitation and adherence to equipment surfaces

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