ORIGINAL PAPER Poly (acrylic acid-co-acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin: new supper metal ion adsorbing hydrogels Farhad Narimani 1 & Moslem Mansour Lakouraj 1 Received: 21 September 2015 /Accepted: 18 February 2016 # Springer Science+Business Media Dordrecht 2016 Abstract Dextrin as a biodegradable natural polymer has hy- drophilic nature that capable to increase the swelling proper- ties and biodegradability of the synthetic hydrogels. This study describes the synthesis of a poly (acrylic acid-co- acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin superabsorbent hydrogels (ADA) via solution poly- merization. The effects of acryloyl tetrasodium thiacalix[4]arene tetrasulfonate (ACSTCA) dose (20–60) on swelling properties of the hydrogels were studied. The synthe- sized hydrogels were characterized by FTIR, TGA, DMTA and rheometry. The metal ion removal capacity of the gels was investigated by atomic absorption for Cd 2+ , Pb 2+ , and Hg 2+ . The tendency of metal ions adsorption decreased in the order of Pb 2+ >Cd 2+ >Hg 2+ . The effect of key operating parameters including ACSTCA content, contact time, adsor- bent dosage, solution pH, and crosslinker density was exper- imentally studied on Pb 2+ adsorption from aqueous solution. The equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherms. Our experimental data are in best agreement with Freundlich isotherms, and adsorption of metal cation onto hydrogel followed a pseudo second-order kinetic model. According to the thermodynamic parameters, the adsorption of Pb 2+ occurred spontaneously. The hydrogels could be regenerated after releasing heavy metal ions, and reused 5 times with less than 7 % loss of adsorption capacity. Keywords Hydrogel . thiacalix[4]arene . Metal ion absorption . Adsorption isotherm . Dextrin Introduction Industrial developments and world population generate more and more of liquid and solid wastes. Heavy metal contami- nants, besides other pollutants, have increased to dangerous levels for living organism in many regions [1], and would endanger public health and the environment if discharged without adequate treatment. Heavy metals are natural components of the Earth’ s crust, water supplies, mine waters, and provided by industrial efflu- ents which cannot be degraded or destroyed, and unfortunate- ly, the risky heavy metals normally are accumulated in living tissues of organism. To a small extent they enter our bodies via food, drinking water and breathing. Therefore removal of toxic heavy metals from wastewater has received much attention in recent years. Various treat- ments such as chemical precipitation [2], coagulation–floccu- lation [3], reverse osmosis [4], ultra-filtration [1], electro- dialysis [5], flotation [6] and ion exchange [7] have been in- troduced to remove heavy metals from contaminated water. Among these, adsorption is widely employed, as adsorbents can bind and capture heavy metal ions from the aqueous so- lutions. Abundance, easy processing, high selectivity, large surface area, durability, and repeated use are general require- ments for an adsorbent. So far, several natural or synthetic materials have been used for this purpose [8–23]. Among them, the polymeric hydrogels have been widely used as ad- sorbents in removal of heavy metal ions from aqueous solutions[24–28]. However, many adsorbents, as well as being economically expensive, have disadvantages such as low adsorption Electronic supplementary material The online version of this article (doi:10.1007/s10965-016-0956-y) contains supplementary material, which is available to authorized users. * Moslem Mansour Lakouraj Lakouraj@umz.ac.ir 1 Department of Organic-Polymer Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 71416, Mazandaran, Iran J Polym Res (2016) 23:62 DOI 10.1007/s10965-016-0956-y