Characterization of Phosphate-Free Detergent Powders Incorporated with Palm C16 Methyl Ester Sulfonate (C16MES) and Linear Alkyl Benzene Sulfonic Acid (LABSA)

Laboratory and pilot scale investigations were carried out on phosphate-free detergent (PFD) formulations comprising binary anionic surfactants of C16 palm methyl ester sulfonates (C16MES) and linear alkyl benzene sulfonic acid (LABSA) with the aim of maximizing the incorporation of C16MES into low density detergent powders without compromising the detergency and other significant properties. Initial laboratory experiments revealed that the detergent powder resulting from C16MES/LABSA with a 50:50 ratio and pH 7–8 has acceptable detergency stability over 1 week of accelerated ageing test at 50 °C and 85 % relative humidity. Subsequent experiments were carried out in a 5-kg/h-capacity pilot spray dryer using PFD formulations of C16MES/LABSA over the whole range of weight ratios under the same pH of 7–8. The concentration of the detergent slurry and cleaning performance (detergency, foaming ability and wetting power) of the resulting spray dried detergent powder (SDDP) were evaluated. C16MES/LABSA in a 40:60 ratio was selected as the ideal formulation based on its optimum detergent slurry concentration and comparable cleaning performance against the control formulation. Further environmental tests have confirmed that SDDP obtained from the ideal formulation is readily biodegradable (60 % in 13 days) and exhibits low eco-toxicity properties (LC₅₀ of 11.3 mg/L).