Adsorption of cadmium, nickel and lead ions: equilibrium, kinetic and selectivity studies on modified clinoptilolites from the USA and RSA

Abstract

The performance of modified clinoptilolites (zeolites) from two different sources (South Africa and the USA) for the adsorption of Ni, Cd and Pb from synthetic industrial effluent contaminated with metal concentration levels at 50, 150 and 500 ppm was evaluated. The selectivity of the clinoptilolite for the adsorption of Ni, Cd and Pb was investigated with mixed feed solutions containing all three ions in equal concentrations and single-component concentrations containing only one of the ions. The homoionic forms of the clinoptilolite were made of Na, K and Ca. Batch experiments were then conducted to measure the uptake of metals by the zeolites. The zeolites were characterised using SEM, XRD and BET. The South African clinoptilolite showed a higher surface area and pore volume (17.52m/g and 0.047cm/g respectively) than the USA zeolite (12.26m/g and 0.028cm/g respectively) for the Na homoionic form. According to the equilibrium studies, the selectivity sequence was found to be Pb > Cd > Ni, with good fits being obtained using Langmuir and Freundlich adsorption isotherms for low metal concentrations. Examples of equilibrium adsorption capacities for RSA and USA clinoptilolite modified with Na for Pb were 26.94 mg/g and 27.06 mg/g when RSA-Na and USA-Na were used respectively. The adsorption was found to depend on the homoionic form of the zeolite and to a lesser extent the source of the zeolite. The selectivity of a particular zeolite for a particular heavy metal can be altered by the homoionic form of the zeolite. Overall, the adsorption capacity of the USA clinoptilolite was higher than the adsorption capacity of the SA clinoptilolite, revealing the potential of clinoptilolite in metal-polluted industrial effluent treatment.

Zeolite Clinoptilolite: Therapeutic Virtues of an Ancient Mineral

“…These experiments confirm the safety as no increased aluminum ions concentrations were detected neither in serum nor in organs of animals after supplementation with PMA-ZC and TMAZ [4]. The pores of the ZC, in addition to metal cations and water, can interact with other molecules and ionic groups of organic origin, such as ammonia and nitrates, which bind with different levels of affinity [26,27]. Thanks to these exceptional ion interactions properties, ZC is considered as one of the key important inorganic cation exchangers and heavily applied in many industrial sectors such as in the treatment of waste-water, nuclear waste, cultivated fields, animal husbandry, or as oral supplementation in humans [5].…”

Solid Phase Extraction of Trace Amounts of Praseodymium Using Transcarpathian Clinoptilolite

“…This adsorbent is the most common among all natural zeolites. It is often used as a sorbent in the solid phase extraction method [13][14][15][16][17].…”

Effect of the adsorbent dose and initial contaminant concentration on the removal of Pb(II) in a solution using Opuntia ficus Indica shell

“…The setting parameters are summarized in Table 3. Based on Figure 8, a fast adsorption rate is observed during the first 40 min, reaching equilibrium at about 80 min, which implies a high selectivity of the active sites by the metal ions (Gorimbo, Taenzana, Muleja, Kuvarega, & Jewell, 2018;Taşar, Kaya, & Ozer, 2014).…”