Experimental study on scale inhibition performance of a green scale inhibitor polyaspartic acid

Abstract

Static and dynamic experiments were carried out to validate scale inhibition performance of a green scale inhibitor-polyaspartic acid (PASP). From the static experiment, it was shown that below 60℃, polyaspartic acid is very effective in scale inhibition, with the scale inhibition ratio exceeding 90% with only 3 mg/L PASP for the 600 mg/L hardness solution. For a higher hardness solution of 800 mg/L, the scale inhibition ratio can also reach 90% with 6 and 12 mg/L PASP at 30 and 60℃respectively. The SEM photographs of CaCO 3 crystals indicate that the crystal structure transforms from a compact stick-shape to a loose shape so that the scale can be washed away easily instead of being deposited on the heat transfer surface. The dynamic experimental results show that almost no scales formed on the heat transfer surface and the fouling thermal resistance decreases extraordinarily if PASP is added in the solution.polyaspartic acid, scale inhibition, fouling resistanceIn cooling water systems of industry, mineral ions in water, such as bicarbonate and calcium, may concentrate to form scale in heat transfer equipment, for example, heat exchangers, evaporators, condensers etc. The scale not only degrades performance of heat exchangers by increasing the resistance to heat transfer, but also wastes energy due to increasing power of pumps, resulting in tremendous economic loss. In order to control scale, numerous chemicals have been used widely in the cooling water systems. With the increase of environmental awareness, people pay much more attention to the study of new green scale inhibitors all over the world [1,2] .A green scale inhibitor named polyaspartic acid (PASP) without phosphorus was developed in the nineties. It is produced without any environmental pollution and can be degraded completely by microbes and epiphytes after being used [3][4][5][6] . In China, people have performed relevant researches and published many papers, in which PASP was reported as a good substitute of other conventional scale inhibitors and a kind of valuable green scale inhibitor [7][8][9][10][11][12][13] . However, most of the studies focused on the chemical syntheses of PASP rather than its scale inhibition performance. Experimental data of the scale inhibitor are not enough to validate its performance of scale inhibition. In addition, the static method is usually used to estimate the scale inhibition behavior, but it does not involve dynamic influence. The dynamic method is regarded as a credible evaluating method because of its simulating actual fouling processes of heat exchangers more factually [14] . In this paper, static and dynamic experiments were conducted to study the scale inhibition performance of PASP for the further application of PASP in industrial circulating water systems.

Synthesis and characterization of novel polyaspartic acid/urea graft copolymer with acylamino group and its scale inhibition performance

“…As a typical green degradable scale inhibitor, PASP presents a good prospect because of its non-toxicity, non-phosphorus and good biodegradability [15][16][17]. Meanwhile, PASP molecule contains carboxylic group with fine chelating ability [18][19][20][21][22][23][24][25] and dispersibility [26][27][28], which is associated with scale inhibition property.…”

A Review of Green Scale Inhibitors: Process, Types, Mechanism and Properties

“…It is a biodegradable polymer having no phosphorus atom and showing excellent performance on sulfate and carbonate scales of Ca 2+ . PASP can be widely produced by several methods in the presence or absence of a catalyst, which has been reported by many researchers [108][109][110][111][112][113][114]. Commonly, many processes are involved in the formation of polysuccinimide that can be hydrolyzed into salt or acid form.…”

State of the art of synthetic threshold scale inhibitors for mineral scaling in the petroleum industry: a review

“…PASP is one of the commonly applied scale inhibitors. It has been widely applied in the oil and gas industry due to its good environmental and inhibition performance (Ajikumar et al 2005;Migahed et al 2016;Quan et al 2008;Thombre and Sarwade 2005). It is a non-phosphorous biodegradable polymer, showing excellence performance on CaSO 4 and CaCO 3 scales.…”