Adsorption isotherms and kinetics pertinent to modified composite hydrogel adsorbents adopted for heavy metals removal

Mohamed H Sorour,Marwa M El Sayed,Heba A Hani,Hayam F Shaalan,Mahmoud A El-Toukhy

doi:10.6703/ijase.202109_18(5).009

Mohamed H Sorour, Marwa M El Sayed + Show 3 more

Open Access

https://doi.org/10.6703/ijase.202109_18(5).009

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Abstract

ABSTRACT Environmental friendly adsorbents constitute an effective method for heavy metals pollution mitigation. In this work, batch adsorption experiments were conducted for the adsorption of various heavy metals including Cr, Co, Ni and Pb using cost-effective modified adsorbents. These comprise polyacrylate hydrogels prepared using microwave (M) irradiation technique (ACM) or ultrasonic (U) irradiation technique (ACU). Further blends of acrylic acid salts with Egyptian kaolin (AKM and AKU) or zeolite (AZM and AZU) were also investigated. The effect of pH and initial concentration on the performance of the composite hydrogels has been studied. Also, several adsorption isotherm and kinetic models were studied. AKU revealed the highest maximum adsorption capacities among other investigated composites for all the tested heavy metals. The equilibrium adsorption experiments revealed that Langmuir isotherm model is best fitted than other models with maximum adsorption capacities of 84.5, 73.3, 61 and 97 mg/g for Cr, Co, Ni and Pb, respectively and equivalent results were obtained from Tempkin isotherm for all ions except Ni. Adsorption kinetics of Cr, Co, Ni and Pb using all the composite hydrogels were best described with the Pseudo-second order kinetic model.

Highlights

Heavy metals pollution is receiving increasing endeavors from the research community in recognition of its documented serious effects on health and the environment
Adsorption kinetics of Cr, Co, Ni and Pb using all the composite hydrogels were best described with the Pseudo-second order kinetic model
Microwave prepared hydrogel samples while; Co and Ni uptake was slightly increased after kaolin and zeolite addition

Summary

Introduction

Heavy metals pollution is receiving increasing endeavors from the research community in recognition of its documented serious effects on health and the environment. Green adsorbents based on modified natural polymers and their composites are the focus of numerous research groups around the world. These green adsorbents comprise for example chitosan, cellulose ones, alginates (Gomez-Maldonado et al, 2019). Modified clays and zeolite adsorbents are used in current practices (Renu and Singh, 2017). One of the materials that is gaining wide acceptance is hydrogel which has numerous advantages for heavy metals removal.

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