Bentonite organo-clay/anthracite mixture in the granular form (EC-1 00) wasused in filtration (column) studies in treating four representativeoil-in-water emulsions. The oilin- water emulsions used were as follows:standard mineral oil (SMO); Kutwell45 (KUTJ and Valcool (VAL), two cuttingoils; and refinery efluent (RE) from the Co-operative Oil Refinery, Regina, Saskatchewan The concentrations of oil in oily waters varied from 8.3 to 69.3mg/L. Eight-hour column studies were conducted in a 19 mm ID, 450 mm/l200 mmlong cast acrylic pipe with organo-clay/anthracite depth of 300 mm/l000 mm. The SMO, KUT, and VAL oil-in-water emulsions were pumped into the column at fourflow rates of 3, 6, 9, and 12 mL/min (0.3, 0.5, 0.8, and I.0gpm/ft2, respectively). Column breakthrough studies were conductedin a 19 mm ID, 1200 mm long cast acrylic pipe using the organo-clay/anthracitemixture of IO00 mm depth. The study was conducted for SIUO, KUT, VAL and REoil-in-water emulsions with a flow rate of 12 mUmim (I gpm/ft2). Theeight-hour column tests with 300 mm bed depth and all oilin- water emulsionsindicated that generally, the oil removal efficiencies decreased with anincrease in flow rate. The percentage redaction in oil removal efficiency was29 and 37 for SMO, 51 and 59 for Km, and 9 and 57 for VAL when the flow ratewas increased from 3 mUmin to 6 and 9 mLJmin, respectively. The results of theeight-hour experiments with 1000 mm depth of organo-clay/anthracite bed andwith a flow rate of I2 mUmin showed that oil removal eficiency for SMO, KUT, and VAL varied between 65 and 70 percent. In the case of RE which is a treatedand highly stable emulsion, the oil removal efficient was found to be 99.5percent. The results from the breakthrough studies clearly indicated that theThomas' equation provides a reasonable fit of the data. The oil-sorptioncapacities (x/m) based on a mass balance analysis were found to be 0.0036,0.0019, 0.0015, and 0.0018 for SMO, KUT VXL, and RE, respectively. The analysisof breakthrough data using Thomas model resulted in similar values of x/m. Theresults also showed that uptake of oil by organo-clay/anthracite mixture canwell be described by a simple equation involving time such as Weber and Mowismodel.
Organo-clay can be described as modified bentonite. The modification processbecomes complete by exchanging the inorganic cations (sodium and calcium)present on the surfaces and interlayer spaces of clays by the nitrogen end of aquaternary amine, and thus changing the hydrophilic nature of clays toorganophilic1,2, As a result, organo-clays become excellent sorbentsfor hydrophobic organics such as oie. An advantage of organo-clay compared toother sorbents is that it can selectively remove organic pollutants fromcontaminated waters.
The sorptive nature of bentonite organo-c1ay for some organic pollutants hasbeen extensively studied4,s,6,7,8. However, the effectiveness oforgano-clay/anthracite mixture as a filter in the removal of oil from water hasnot been studied extensively. Alther (1995/found bentonite organo-clayeffective in the removal of oil from oily waters.