Chloride removal from recycled cooling water using ultra-high lime with aluminum process.
Chloride is a deleterious ionic species in cooling water systems because it promotes corrosion, and most of the scale and corrosion inhibitors are sensitive to chloride concentration in the water. Chloride can be removed from cooling water by precipitation as calcium chloroaluminate [Ca4Al2Cl2(OH)12]. A set of equilibrium experiments and one kinetic experiment were conducted to evaluate chloride removal using the ultra-high lime with aluminum (UHLA) process and to characterize the equilibrium conditions of calcium chloroaluminate precipitation. A total of 48 batch-equilibrium experiments were conducted on a 30 mM NaCl solution over a range of values for lime dose (0 to 200 mM) and sodium aluminate dose (0 to 100 mM). Experimental results showed that the UHLA process can remove chloride and that the formation of a calcium chloroaluminate solid phase is a reasonable mechanism that is able to adequately describe experimental results. An average value of the ion activity product of 10(-94.75) was obtained and can be used as an estimate of the solubility product for Ca4Al2Cl2(OH)12.
Abdel-Wahab
Ahmed
A
Civil Engineering Department, Texas A&M University, College Station 77843-3136, USA.
Batchelor
Bill
B
D000535:Aluminum / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry*; D011232:Chemical Precipitation; D002712:Chlorides / Q000737:chemistry / Q000302:isolation & purification*; D003247:Conservation of Natural Resources; D007477:Ions; D010087:Oxides / Q000737:chemistry*; D012995:Solubility; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
D017610:Calcium Compounds; D002712:Chlorides; D007477:Ions; D010087:Oxides; C016538:lime; D000535:Aluminum