Removal of toxic lead from aqueous solution using a low-cost adsorbent.

Valorization of waste materials and byproducts as adsorbents is a sustainable approach for water treatment systems. Pottery Granules (PG) without any chemical and thermal modification were used as a low-cost, abundant, and environmentally benign adsorbent against Pb(II), the toxic metal in drinking water. The porous structure and complex mineral composition of PG made it an efficient adsorbent material for Pb(II). The effect of key physicochemical factors was investigated to determine the significance of contact time, PG dose, pH, solution temperature, and coexisting ions, on the process. Pb(II) removal increased by PG dose in the range of 5-15 g/L, and agitation time from 5 to 60 min. Increasing Pb(II) concentration led to a drop in Pb(II) removal, however, adsorption capacity increased significantly as concentration elevated. Pb(II) removal also increased significantly from ~ 45% to ~ 97% by pH from 2 to 12. A ~ 20% improvement in Pb(II) adsorption after rising the solution temperature by 30˚C, indicated the endothermic nature of the process. The sorption was described to be a favorable process in which Pb(II) was adsorbed in a multilayer onto the heterogeneous PG surface. The qmax of 9.47 mg/g obtained by the Langmuir model was superior among many reported low-cost adsorbents. The Pb(II) adsorption was described well by the Pseudo- first-order kinetic model. Na+, Mg2+, Ca2+, Cd2+, and Zn2+ showed a negligible effect on Pb(II) adsorption. However, the presence of Mn2+ and Fe2+ significantly hindered the process efficacy. In conclusion, the use of waste material such as PG against Pb(II) is a viable option from the economic and effectiveness points of view.

Cadmium in Groundwater Consumed in the Rural Areas of Gonabad and Bajestan, Iran: Occurrence and Health Risk Assessment.

Evidences show that high levels of cadmium intake may be contributing to a wide range of deleterious health effects. This study was performed to estimate the concentration of cadmium and the health risk to human by cadmium through the ingestion of groundwater in 39 rural areas of Gonabad and Bajestan, eastern Iran. The mean cadmium concentrations in groundwater in the studied rural areas of Gonabad and Bajestan ranged from 0.087 to 14.32 µg/L and from 0.417 to 18.36 µg/L, respectively. Health risk quotient for cadmium contamination for 16 and 38% of children and infants in rural areas of Gonabad and Bajestan, respectively, was more than 1 which causes non-carcinogenic risk to the local population. The carcinogenic risk of cadmium in drinking water for adults, children, and infants in 16, 33, and 33% of studied rural areas of Gonabad and Bajestan, respectively, was higher than the safe limit of 1.0 × 10-4. For rural areas of Bajestan, the cancer risk in 42, 52, and 52% of adults, children, and infants was above the safe limit. It was strongly suggested that the accessible procedures of treatment should be taken for a portion of contaminated rural areas before the distribution of the groundwater for the local population.