Emerging Contaminants Removal from Wastewater Using Organo-Modified Bentonite Clay

Abstract

Organo-modified bentonite clay locally sourced from Bauchi State, Nigeria was prepared and used as an adsorbent for Emerging Contaminants (EC) capture from Kaduna Polytechnic female hostel wastewater. The produced adsorbent was characterized to determine the functional groups, surface area and crystal structure. Surface area for directly modified bentonite clay produced adsorbents and oxalic acid-pretreated bentonite clay adsorbent was found to be 625 m2/g and 349.2 m2/g respectively and the morphology of the produced acid-pretreated organo-modified bentonite clay adsorbents has better pore development with a higher amorphous structure. The wastewater compositions were found to contain major ECs identified to be Diclofenac, Triclosan, Methylparaben, and Bisphenol A, which account for 76.206% of the ECs that are detrimental to human and the environment. The impact of the adsorption factors; contact time, adsorbent dosage, and temperature on uptake behavior were all examined. Effect of adsorbent dosage was established which shows that all ECs removed rise rapidly from 0.5 – 1.0 g adsorbent dosage and then slowly reach a maximum of 98.65% Triclosan, 95.83% Diclofenac, 91.49% BPA, and 62.16% Methyl-Paraben removal as adsorbent dosage increases to 2g. On the other hand, as the adsorbent dosage increases to 3g, the removal rate of all ECs was observed to drop slightly and then attain maximum removal as the dosage rises to 4g. In contrast, a rise in adsorbent dosage of 2.5g gives a sudden drop in removal of Triclosane to 92.41% and Methyl-Paraben to 53.01% as well as a sharp drop in Methyl-Paraben to 33.33% and slightly drop in the removal of all other ECs. Langmuir and Freundlich isotherms models were fitted to the adsorption data and Freundlich showed best fit indicating chemisorption. The adsorption of triclosan, diclofenac, bisphenol A, and methylparaben followed pseudo second-order kinetic model.