Nature-Inspired Coral-like Layered [Co0.79Al0.21(OH)2(CO3)0.11]·mH2O for Fast Selective ppb Level Capture of Cr(VI) from Contaminated Water

Iron-loaded Punica granatum peel: An effective biosorbent for the excision of arsenite from water

The occurrence of arsenic in the surroundings raises apprehension because its detrimental impacts on both human health and the ecology. Since adsorption is an effective, affordable method that can be adjusted to specific environmental circumstances, it is a sustainable solution for the removal of arsenic from the aquatic environment. Utilizing biomass that has been chemically activated may be a viable way to increase the adsorption capacity of the material, reduce arsenic pollution, and protect the environment and human health. In the proposed research, Fe(III) loaded saponified Punica granatum peel (Fe(III)-SPGP) has been synthesized to remove arsenic from aqueous solutions. FTIR and SEM analysis were utilized to carry out the characterization of the biosorbents. Batch experiments were carried out by altering several factors including pH and contact time, in addition to initial concentration and desorption. The most effective pH for As(III) adsorption using Fe(III)-SPGP was discovered to be 9.0. After determining that a pseudo-second-order kinetic model was the one that provided the greatest fit for the results of the experiment, the model developed by Langmuir was applied. It was discovered that the maximum adsorption of As(III) that could be adsorbed by Fe(III)-SPGP was 63.29 mg/g. The spent biosorbent may easily be reused again in subsequent applications. Based on these findings, Fe(III)-SPGP shows promise as a cheap effective sorbent for excising contaminants of As(III).

Acid-treated pomegranate peel; An efficient biosorbent for the excision of hexavalent chromium from wastewater

We studied the sequestration of hexavalent chromium Cr(VI) from an aqueous solution using chemically modified pomegranate peel (CPP) as an efficient bio-adsorbent. The synthesized material was characterized by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). The impacts of parameters like solution pH, Cr(VI) concentration, contact time, and adsorbent dosage were investigated. Experimental results of the isotherm studies and adsorption kinetics were found agreeing to the Langmuir isotherm model and pseudo-second-order kinetics, respectively. The CPP showed appreciable Cr(VI) remediation capacity with a maximal loading capacity of 82.99 mg/g at pH 2.0, which was obtained in 180 min at room temperature. Thermodynamic studies revealed the biosorption process as spontaneous, feasible, and thermodynamically favorable. The spent adsorbent was eventually regenerated and reused, and the safe disposal of Cr(VI) was ensured. The study revealed that the CPP can be effectively employed as an affordable sorbent for the excision of Cr(VI) from water.

Removal of CrO42-, a Nonradioactive Surrogate of 99TcO4-, Using LDH-Mo3S13 Nanosheets

Removal of chromate (CrO₄^2-) and pertechnetate (TcO₄^-) from the Hanford Low Activity Waste (LAW) is beneficial as it impacts the cost, life cycle, operational complexity of the Waste Treatment and Immobilization Plant (WTP), and integrity of vitrified glass for nuclear waste disposal. Here, we report the application of [Mo^IV₃S₁₃]^2- intercalated layer double hydroxides (LDH-Mo₃S₁₃) for the removal of CrO₄^2- as a surrogate for TcO₄^-, from ppm to ppb levels from water and a simulated LAW off-gas condensate of Hanford's WTP. LDH-Mo₃S₁₃ removes CrO₄^2- from the LAW condensate stream, having a pH of 7.5, from ppm (∼9.086 × 10⁴ ppb of Cr⁶⁺) to below 1 ppb levels with distribution constant (K_d) values of up to ∼10⁷ mL/g. Analysis of postadsorbed solids indicates that CrO₄^2- removal mainly proceeds by reduction of Cr⁶⁺ to Cr³⁺. This study sets the first example of a metal sulfide intercalated LDH for the removal of CrO₄^2-, as relevant to TcO₄^-, from the simulated off-gas condensate streams of Hanford's LAW melter which contains highly concentrated competitive anions, namely F^-, Cl^-, CO₃^2-, NO₃^-, BO₃^3-, NO₂^-, SO₄^2-, and B₄O₇^2-. LDH-Mo₃S₁₃'s remarkable removal efficiency makes it a promising sorbent to remediate CrO₄^2-/TcO₄^- from surface water and an off-gas condensate of nuclear waste.

Efficient biosorption of hexavalent chromium from water by modified arecanut leaf sheath

In this work, the excision of hexavalent chromium (Cr(VI)) was studied from an aqueous solution using the chemically modified arecanut leaf sheath (CALS) as a novel bio-adsorbent. The as-prepared adsorbent was characterized by using instrumental methods including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effect of several factors, including solution pH, contact time, and sorbent dosages were examined to identify the optimum condition for the sorption ability. The optimal pH of Cr(VI) biosorption was 2.0, and equilibrium was reached in 150 min. Adsorption was shown to be pseudo-second-order in kinetic investigations, and the Langmuir isotherm with maximal adsorption efficiency was determined as 109.89 mg/g. The spent biosorbent can be easily regenerated and reused. For the biosorption of oxyanions of chromium, both electrostatic attraction and ligand exchange mechanism play critical roles. From the results, the CALS appears to be a potential low-cost effective sorbent to remove Cr (VI) from water.