4.2.7. Different types of wastes sludges as adsorbent
Different industries produce sludge as by-products which have been examined as adsorbents by various researchers. Chrome sludge, a solid waste material from an electroplating industry, was used as an adsorbent for As(V) removal by Lee and Lee. The maximum sorption capacity of chrome sludge for As(V) was reported as 21 mg/g. Chrome sludge was also tested to remove dyes from aqueous solutions and the results indicated that the sludge had a better affinity for acid dyes than basic dyes.
Color removal of an aqueous solution containing water-based inks, a mixture of resins, pigments, and dyes, was investigated by using metal hydroxide sludge, which is a waste from the electroplating industry by Netpradit et al.. The maximum adsorption capacity for the red ink was reported as 34.48 mg/g of metal hydroxide sludge. Waste metal hydroxide sludge was used as low-cost adsorbent for removing a reactive textile dye (Remazol Brilliant Blue) by Santos et al.. The maximum adsorption capacity of 91.0 mg/g was found at 25 ◦C and pH 7.