Modifying Natural Zeolites to Improve Heavy Metal Adsorption

Abstract

Problems with increasing heavy metal contents in natural waters are becoming a global issue. At the same time, improved methods for water treatment are becoming increasingly important. In this context, natural zeolites can be used to purify polluted water. In this paper, we investigated how the adsorption capacity of natural zeolites can be improved. Natural zeolites from the Shankanay district, Almaty, Kazakhstan, were used as adsorbent material for experiments on improving the water treatment of heavy metals. We found that the adsorption capacity for heavy metals was increased greatly by thermal activation using furnace treatment. The optimal thermal activation condition was about 550 °C for a duration of 2 h. However, the improved adsorption capacity for different heavy metals varied depending on the heat treatment temperature. Adsorption by the heat-treated zeolites at a temperature of 550 °C was 87% for nickel, 99% for copper and cadmium, and 100% for lead. Adsorption by heat-treated zeolites at a temperature of 500 °C was 78% for nickel, 98% for copper, 83% for cadmium, and 88% for lead. The residual concentration of heavy metals in the filtered water did not exceed the maximum permissible concentrations for drinking purposes. In all experiments, intense adsorption took place during the first 10 min representing 35 to 61% of the metal ions in the water. Adsorption properties were verified using adsorption capacity (BET), IR spectroscopy, and scanning electron microscopy. The study shows that modified Shankanay natural zeolites have great potential as a low-cost adsorbent material for purifying water from heavy metals.

Modification of natural zeolites and their applications for heavy metal removal from polluted environments: Challenges, recent advances, and perspectives

“…Natural zeolites have great potential as low-cost, capable adsorbent materials for removing heavy metals from different sources contaminating the water [ 97 ]. The main challenges toward achieving the effective remediation of waters are the efficiency of used natural zeolites, their regeneration and the safe disposal of the wasted adsorbents [ 70 , 74 , 98 ]. The pH of the aqueous media strongly influences the CEC of used natural zeolite for heavy metals removal [ 98 ].…”

“…The main challenges toward achieving the effective remediation of waters are the efficiency of used natural zeolites, their regeneration and the safe disposal of the wasted adsorbents [ 70 , 74 , 98 ]. The pH of the aqueous media strongly influences the CEC of used natural zeolite for heavy metals removal [ 98 ]. It should be also noted that the sorption of divalent metal ions from multicomponent systems is generally lower than that of single-component systems, a possible explanation being the competition between ions [ 48 ].…”

Facile Synthesis of Sodium Dodecyl Sulfate Intercalated Mg‐Al LDH and its Excellent Adsorption Performances for Cu2+ from Aqueous Solution

“…For instance, Kuldeyev et al demonstrated the the potential of heat-treated natural zeolite as a robust adsorbent for heavy metal removal. [17] Zhang et al developed a nanofiltration membrane composed of a polyamide film doped with phytic acid, exhibiting exceptional binding affinity for heavy metal cations and high removal efficiency. [18] Lin et al fabricated composite physical hydrogels using chitosan/sodium alginate/bentonite (CTS/SA/BT), which hold promising application prospects in the field of heavy metal remediation.…”

Zeolite Properties, Methods of Synthesis, and Selected Applications

“…By means of thermal treatment, this water can be easily removed without disturbing the crystal structure of the zeolite ( Figure 1 ). The released pores can be filled with water molecules or other adsorbates [ 5 , 8 ].…”