The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer
Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures
was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of
PAA, with the greatest inhibition seen for PAA with hydrophobic end groups of moderate size (6–10 carbons).
The morphologies of CaCO3 crystals were significantly distorted in the presence of these PAAs. The smallest
morphological change was in the presence of PAA with long hydrophobic end groups (16 carbons) and the relative
inhibition observed for all species were in the sameorder at 30 °C and 100 °C. Aswell as distorting morphologies,
the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a
degree proportional to their ability to inhibit precipitation.
The inhibition efficiency of PAAwith different end groups and molar
masses as scale inhibitors to prevent CaCO3 formation in bulk solution
was studied at temperatures ranging between 25 and 100 °C using conductivity
and turbidity. The results showed that both molar mass and
the nature of the end group of PAA affect the inhibition of CaCO3 scale.
Low molar mass PAA with short and moderately-sized end groups had
relatively high inhibition efficiency and long induction times under all
conditions investigated, while all high molar mass PAAs had poor
inhibition efficiency of CaCO3. Low molar mass PAA with long hydrophobic
end groups had poor inhibition efficiency of CaCO3 scale. At
room temperature, the lowest molar mass of PAA with hydrophilic
end group showed good efficiency in the inhibition of CaCO3 scale
making it suitable for use as a scale inhibitor in RO desalination.
However, with increasing temperature, the lowest molar mass of PAA
with different middle hydrophobic end groups gave a better inhibition
efficiency and induction time than PAA with hydrophilic end groups.
These results suggest that the lowest molar mass PAA with end groups
of moderate hydrophobicity are more suitable as scale inhibitors in MSF
desalination.
Effectiveness of the inhibitors declinedwith increasing temperature,
but the relative effectiveness of the inhibitors according to end-group
remained essentially the same. At 100 °C, 0.5 ppm PAA applied to a
systemwith SL=277 gave approximately the same inhibition efficiency
(% IE) as 6.7 ppmapplied at SL= 1629,with the order of efficiency of
the different end-groups being almost identical.
The nature and length of end groups of PAA had a major effect on
themorphologies of CaCO3 obtained at 100 °Cwith 6.7 ppm. The highest
distortion in the CaCO3 polymorphswas for PAAwithmid-hydrophobic
end groups. However, the lowest distortion in different CaCO3 polymorphs
was for PAA with long-hydrophobic end groups. These results
may due to its rate of adsorption/desorption on the active faces of
CaCO3 polymorphs. The conductivity and morphology results are compatible,
where the % IE of CaCO3 formation and the distortion of its morphologies
have the same order of HIB N CIB N CMM N HDIB N DIB. As
previously observed with the calcium oxalate system, the PAA appears
to be stabilizing the initially-formed kinetically-favored product so it
is not transformed to the thermodynamic product, though less
Table 4
The relationship between the nature and length end groups of PAA and the distortion and speciation of CaCO3 polymorphs under condition set 4.
End-group % IE Distortion Average rod
length (μm)
Average vaterite
diameter (μm)
Predominant polymorph
None 0 None 63 20 Rod-like
CMM 66 Moderate 19 9.5 Rhombohedral calcite
HIB/CIB 100/94 High 14 9 Mixture of rod-like, vaterite and
DIB 20 Low 29 13 rhombohedral calcite
HDIB 45 Low 28 21
104 A.A. Al-Hamzah et al. / Desalination 338 (2014) 93–105
comprehensively. The crystals formed are more ill-defined than observed
in the calcium oxalate system, which may be related to the
higher concentration of polymer employed, a smaller difference in
charge density between crystal growth faces, or some other unidentified
feature of the system.
The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer
Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures
was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of
PAA, with the greatest inhibition seen for PAA with hydrophobic end groups of moderate size (6–10 carbons).
The morphologies of CaCO3 crystals were significantly distorted in the presence of these PAAs. The smallest
morphological change was in the presence of PAA with long hydrophobic end groups (16 carbons) and the relative
inhibition observed for all species were in the sameorder at 30 °C and 100 °C. Aswell as distorting morphologies,
the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a
degree proportional to their ability to inhibit precipitation.
The inhibition efficiency of PAAwith different end groups and molar
masses as scale inhibitors to prevent CaCO3 formation in bulk solution
was studied at temperatures ranging between 25 and 100 °C using conductivity
and turbidity. The results showed that both molar mass and
the nature of the end group of PAA affect the inhibition of CaCO3 scale.
Low molar mass PAA with short and moderately-sized end groups had
relatively high inhibition efficiency and long induction times under all
conditions investigated, while all high molar mass PAAs had poor
inhibition efficiency of CaCO3. Low molar mass PAA with long hydrophobic
end groups had poor inhibition efficiency of CaCO3 scale. At
room temperature, the lowest molar mass of PAA with hydrophilic
end group showed good efficiency in the inhibition of CaCO3 scale
making it suitable for use as a scale inhibitor in RO desalination.
However, with increasing temperature, the lowest molar mass of PAA
with different middle hydrophobic end groups gave a better inhibition
efficiency and induction time than PAA with hydrophilic end groups.
These results suggest that the lowest molar mass PAA with end groups
of moderate hydrophobicity are more suitable as scale inhibitors in MSF
desalination.
Effectiveness of the inhibitors declinedwith increasing temperature,
but the relative effectiveness of the inhibitors according to end-group
remained essentially the same. At 100 °C, 0.5 ppm PAA applied to a
systemwith SL=277 gave approximately the same inhibition efficiency
(% IE) as 6.7 ppmapplied at SL= 1629,with the order of efficiency of
the different end-groups being almost identical.
The nature and length of end groups of PAA had a major effect on
themorphologies of CaCO3 obtained at 100 °Cwith 6.7 ppm. The highest
distortion in the CaCO3 polymorphswas for PAAwithmid-hydrophobic
end groups. However, the lowest distortion in different CaCO3 polymorphs
was for PAA with long-hydrophobic end groups. These results
may due to its rate of adsorption/desorption on the active faces of
CaCO3 polymorphs. The conductivity and morphology results are compatible,
where the % IE of CaCO3 formation and the distortion of its morphologies
have the same order of HIB N CIB N CMM N HDIB N DIB. As
previously observed with the calcium oxalate system, the PAA appears
to be stabilizing the initially-formed kinetically-favored product so it
is not transformed to the thermodynamic product, though less
Table 4
The relationship between the nature and length end groups of PAA and the distortion and speciation of CaCO3 polymorphs under condition set 4.
End-group % IE Distortion Average rod
length (μm)
Average vaterite
diameter (μm)
Predominant polymorph
None 0 None 63 20 Rod-like
CMM 66 Moderate 19 9.5 Rhombohedral calcite
HIB/CIB 100/94 High 14 9 Mixture of rod-like, vaterite and
DIB 20 Low 29 13 rhombohedral calcite
HDIB 45 Low 28 21
104 A.A. Al-Hamzah et al. / Desalination 338 (2014) 93–105
comprehensively. The crystals formed are more ill-defined than observed
in the calcium oxalate system, which may be related to the
higher concentration of polymer employed, a smaller difference in
charge density between crystal growth faces, or some other unidentified
feature of the system.
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The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer
Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures
was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of
PAA,กับที่สุดและเห็นป้ากับกลุ่มจบ ) ขนาดพอประมาณ ( 6 – 10 ด้วย )
ลักษณะของผลึกแคลเซียมคาร์บอเนตอย่างมีนัยสำคัญเพี้ยนต่อหน้าแบบนี้ การเปลี่ยนแปลงลักษณะทางสัณฐานวิทยาที่เล็กที่สุด
คือต่อหน้าป้ากับกลุ่มสุดท้าย ( 16 ) นานด้วย ) และญาติ
inhibition observed for all species were in the sameorder at 30 °C and 100 °C. Aswell as distorting morphologies,
the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a
degree proportional to their ability to inhibit precipitation.
The inhibition efficiency of PAAwith different end groups and molar
masses as scale inhibitors to prevent CaCO3 formation in bulk solution
was studied at temperatures ranging between 25 and 100 °C using conductivity
and turbidity. The results showed that both molar mass and
the nature of the end group of PAA affect the inhibition of CaCO3 scale.
Low molar mass PAA with short and moderately-sized end groups had
relatively high inhibition efficiency and long induction times under all
conditions investigated, while all high molar mass PAAs had poor
inhibition efficiency of CaCO3. Low molar mass PAA with long hydrophobic
end groups had poor inhibition efficiency of CaCO3 scale. At
room temperature, the lowest molar mass of PAA with hydrophilic
สิ้นสุดกลุ่มแสดงประสิทธิภาพในการยับยั้งแป้ง
ขนาดทำให้มันเหมาะสำหรับใช้เป็นสารยับยั้งในขนาดโรดาหน้า .
แต่เมื่อเพิ่มอุณหภูมิ ต่ําสุดมวลโมเลกุลของป้า
กลุ่มระดับกลาง ) ต่าง ๆให้มีประสิทธิภาพและการการยับยั้งดีกว่า
เวลากว่าป้ากับกลุ่มจบ
น้ำ .These results suggest that the lowest molar mass PAA with end groups
of moderate hydrophobicity are more suitable as scale inhibitors in MSF
desalination.
Effectiveness of the inhibitors declinedwith increasing temperature,
but the relative effectiveness of the inhibitors according to end-group
remained essentially the same. At 100 °C, 0.5 ppm PAA applied to a
ใช้ SL = 277 ให้ประมาณเดียวกันและประสิทธิภาพ
% IE ) เป็น 6.7 ppmapplied ที่ SL = 1629 ด้วยเพื่อประสิทธิภาพของกลุ่มที่แตกต่างกันในที่สุด
เกือบเหมือนกัน ลักษณะและความยาวของปลายกลุ่มป้ามีผลสำคัญ
themorphologies ของ CaCO3 ที่อุณหภูมิ 100 องศา cwith 6.7 ppm . . สูงสุด
บิดเบือนใน CaCO3 polymorphswas สำหรับ paawithmid )
สิ้นสุดกลุ่มอย่างไรก็ตาม การบิดเบือนต่ำสุดที่แตกต่างกัน ใช้ให้หมด
คือป้ากับกลุ่มจบ ) นาน ผลลัพธ์เหล่านี้
อาจเนื่องจากอัตราของการดูดซับและปลดปล่อยบนใบหน้าใช้
แป้งให้หมด . ผลของความเข้ากันได้ ,
% IE ที่ก่อตัว CaCO3 และการบิดเบือนของโครงสร้าง
มีคำสั่งเดียวกันของฮิบ n n n n CIB CMM hdib ออ . โดย
เคยปฏิบัติกับระบบออกซาเลต แคลเซียม ได้ ป้าจะต้องคงที่เริ่มต้นขึ้น
ชื่นชอบผลิตภัณฑ์จลนศาสตร์ จึงไม่ใช่สินค้าที่เปลี่ยนทาง แต่น้อย
โต๊ะ 4 ความสัมพันธ์ระหว่างธรรมชาติและความยาวกลุ่มจบป้าและการบิดเบือนและชนิดของแป้งให้หมดภายใต้เงื่อนไขชุดที่ 4
จบ กลุ่มคือการเฉลี่ยคัน
%length (μm)
Average vaterite
diameter (μm)
Predominant polymorph
None 0 None 63 20 Rod-like
CMM 66 Moderate 19 9.5 Rhombohedral calcite
HIB/CIB 100/94 High 14 9 Mixture of rod-like, vaterite and
DIB 20 Low 29 13 rhombohedral calcite
HDIB 45 Low 28 21
104 A.A. Al-Hamzah et al. / Desalination 338 (2014) 93–105
comprehensively. The crystals formed are more ill-defined than observed
in the calcium oxalate system, which may be related to the
higher concentration of polymer employed, a smaller difference in
charge density between crystal growth faces, or some other unidentified
feature of the system.
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