Evaluation of the influence of environmental conditions on the removal of Pb(II) from wastewater by Ca-rectorite

Abstract

The removal of Pb(II) from wastewater by Ca-rectorite was investigated as various environmental factors containing contact time, pH, ionic strength, solid content, coexisting ions, humic acid (HA) and temperature. The kinetic sorption of Pb(II) on Ca-rectorite was well described by the pseudo second-order model. The sorption process was strongly dependent on pH and ionic strength. The results indicated that the presence of HA and coexisting ions influenced the sorption of Pb(II) on Ca-rectorite obviously. Besides, the Langmuir and Freundlich models were employed to simulate the sorption isotherms. The thermodynamic A c c e p t e d M a n u s c r i p t 2 parameters indicated that the sorption process was spontaneous and endothermic. It is possible to conclude that Ca-rectorite has a good potential for disposal of lead-contaminated wastewater.

Different Insights into Silicate Rectorite Modification and Its Role in Removal of Heavy Metal Ions from Wastewater

“…Fe(III) (17) Cr(VI) (23) Similar computing methods can also be applied in the species distribution of Cr(VI) and Pb(II), and both of their equilibrium reaction formulas and corresponding reaction coefficients were displayed in Table 4 [32,33]. Based on Table 4, the species distributions of 2.72 × 10 −4 mol/L Cr(VI) and 0.91 × 10 −4 mol/L Pb(II) were described in Figures 9 and 10.…”

“…However, common adsorbents such as activated carbon are expensive, thus some natural resources such as polysaccharides, fly ash and clay have attracted much attention due to their low cost and easy access. In this series of materials, rectorite (REC) was applied more and more in pollutant adsorption from sewage owing to its low cost, high ion exchange capacity and relatively large specific area [14][15][16][17]. It is a sort of rare regularly interstratified silicate and similar to kaolinite.…”

“…There are some cations (Na + , K + and Ca 2+ ) and hydrated cations with exchangeability, which can enlarge its interlayer distance by intercalating cations or polar molecules existing in the interlayer regions.Over several decades, there are more and more investigations on the adsorption of metal ions by REC or its synthesis [17][18][19][20][21]. For example, Mei et al [17] and Zhao et al [22] studied separately the adsorption behaviors of Pb(II) by Ca-rectorite and Sr(II) by Na-rectorite as a function of different environmental parameters including the influence of pH, temperature, ionic strength and humic acid (HA) under ambient conditions. Both of them found that the adsorption results of heavy metals were intensely decided by pH and ionic strength and the adsorption process was spontaneous and endothermic.…”