Novel Calix[4]arene network resin for Cr(VI) ions Remediation: A Response Surface Approach

Ali N Siyal,Saima Q Memon

doi:10.2478/v10026-012-0080-7

Abstract

Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ~100% removal effi ciency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fi tting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal effi ciency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1±2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.

Highlights

Chromium which has been widely used by men for years, can be regarded as a longstanding environmental contaminant as a result of numerous industrial processes such as the leather tanning, electroplating, oxidative dyeing and manufacturing of steel paints and textiles1
In this study we focus on the synthesis of Novel Calix[4]arene Network (NCN) sorbent [7] from Amberlite XAD-2 [1] without using any organic ligand for the treatment of Cr(VI) contaminated water
XAD-2 [1] contains phenyl groups, these phenyl groups were converted into para substituted phenols [5] and these para substituted phenols were converted into NCN resin [7]

Summary

INTRODUCTION

Chromium which has been widely used by men for years, can be regarded as a longstanding environmental contaminant as a result of numerous industrial processes such as the leather tanning, electroplating, oxidative dyeing and manufacturing of steel paints and textiles. Strong exposure to Cr(VI) ion causes cancer in digestive tract and lungs and may cause epigastric pain, nausea, vomiting, severe diarrhoea and hemorrhage. It has adverse impacts on aquatic species as it accumulates in fish tissues and causes reduction in fish production at higher concentration. For the treatment of wastewaters, various sorbents such as impregnated and chemically modified Amberlite XAD series with various organic ligands have been reported. In this study we focus on the synthesis of Novel Calix[4]arene Network (NCN) sorbent [7] from Amberlite XAD-2 [1] without using any organic ligand for the treatment of Cr(VI) contaminated water. This paper reports on the synthesis of a NCN [7] resin and its application with a combined effect of four parameters, viz., adsorbent dose, pH, temperature and adsorbate concentration, a factorial design approach was adopted to optimize the removal efficiency and to study the interaction between effective variables

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS