Application of guar gum for the removal of dissolved lead from wastewater

• Main Authors: Mukherjee, Sumona, Mukhopadhyay, Soumyadeep, Zafri, Muhammad Zakwan, Zhan, Xin Min, Hashim, Mohd Ali, Sen Gupta, Bhaskar
• Format: Article
• Published: Elsevier 2018
• Subjects: TA Engineering (General). Civil engineering (General); TP Chemical technology
• Online Access: http://eprints.um.edu.my/21196/; https://doi.org/10.1016/j.indcrop.2017.10.022

Lead (Pb) is a toxic heavy metal with highly recalcitrant property. It easily accumulates in the food chain by interacting with calcium and iron components of the biomolecules of living organisms. The aim of the study was to develop an efficient method to treat heavy metal containing turbid wastewater without the introduction of any secondary source of pollutants. Guar gum, a long chain polysaccharide was used to remove Pb2+ from turbid wastewater containing kaolinite. Guar gum is extracted from the seed of leguminous shrub Cyamopsis tetragonoloba commonly known as guaran. Potassium alum, a commonly used inorganic coagulant was also studied in order to compare its Pb2+ removal efficiency with the biopolymer. It was observed that guar gum could achieve 83% removal, at an initial Pb concentration of 15 mg L−1. Optimization study using response surface methodology was used to determine the optimal process parameters. FTIR and zeta potential measurement of guar gum-Pb2+ aggregates were used to determine the removal mechanism. FTIR absorption peaks at 3618.79 cm−1 in the flocs indicate hydrogen bonding between Pb2+ and guar gum. Compact and well-formed flocs by guar gum are indicated by the SEM micrographs. In addition to the formation of compact sludge, guar gum is nontoxic and biodegradable and hence highly recommended for treatment of metal containing wastewater. The requirement of ultra-low amount of biopolymer in the range of 1.25 mg L−1 to treat the relatively high volume of water provides an additional financial advantage.