High adsorption performance for trace lead (II) cation from sewage by Fe/Cu metal organic nanosheets modified with terephthalic acid.

A two-dimensional nanoflake (Fe/Cu-TPA) was prepared through a simple ultrasonic-centrifuge method. Fe/Cu-TPA has prominent performance on the removal of Pb2+ with low consistences. More than 99% lead (II) (Pb2+) was removed. The adsorption equipoise was established within 60 min for 50 mg L-1 Pb2+. Fe/Cu-TPA shows excellent regenerability with 19.04% decline of Pb2+ adsorption competence in 5 cycles. There are two models for Fe/Cu-TPA adsorption of Pb2+, pseudo-second-order dynamic model and Langmuir isotherm model, with a utmost adsorption competence of 213.56 mg g-1. This work offers a new candidate material for the industrial-grade Pb2+ adsorbents with promising application prospect.

Significant improvement on selectivity and capacity of glycine-modified FeCo-layered double hydroxides in the removal of As (V) from polluted water.

A series of novel Fe/Co layered double hydroxides modified with glycine (named as FeCo-LDH@G) were prepared and served as high-performance adsorbents for As (V). With a Fe/Co mole ratio of 1:1, the Fe0·02Co0.02-LDH@G adsorbents achieved significant improvements on the adsorption selectivity and capacity for As (V). The As (V) adsorption by Fe0·02Co0.02-LDH@G follows Langmuir isotherm model and pseudo-second-order kinetics model. The maximum adsorption capacity is 820 mg g-1 and the equilibrium reaches in 120 min. Under the assistance of electrochemical devices, the Fe0·02Co0.02-LDH@G adsorbent was regenerated and the adsorption capacity for As (V) was dropped only about 13.41% in 5 cycles. These excellent performances make Fe0·02Co0.02-LDH@G as promising As (V) adsorbents for commercial wastewater treatments.

Excellent selectivity and high capacity of As (V) removal by a novel lignin-based adsorbent doped with N element and modified with Ca2.

As one of the most significant natural polymer with the highest annual yield, lignin has been applied in the treatment of wastewater to remove heavy metal ions. However, there are still some shortages, such as low reactivity, difficulties in adsorbing oxyanions and low selectivity on specific oxyanions. To improve its adsorption properties, a novel lignin-based adsorbent was prepared in this study, doped with nitrogen by Mannich reaction, using triethylenetetramine (TETA) as N source, and further modified with Ca2+. The adsorption of Ca, N-co-doped lignin (Ca@N-Lig) for As (V), Cr (VI) and P (V) was studied. The Ca@N-Lig shows high capacity, excellent selectivity and prominent regeneration ability for As (V) adsorption. The adsorption of Ca@N-Lig for As (V) followed the Langmuir isotherm model and the pseudo-second-order kinetics model, yielding a maximum adsorption capacity of 681.59 mg·g-1 and a fast adsorption equilibrium within 30 min. Ca@N-Lig has an excellent regeneration ability on the adsorption of As (V) with a decrease of about 15.60% after 5 adsorption/desorption cycles. This study offers an efficient way to remove As (V) from polluted water.