Efficient Cr Research Articles

Preparation and Characterization of Low-Cost Bio-Sorbent and a Novel Activated Carbon from Agro-Wastes for Efficient Cr(VI) Removal

This study focuses on the preparation and characterization of a novel highly efficient activated carbon (new-AC) and a low-cost adsorbent (BM) from a mixture of agro-based wastes to remove toxic Cr(VI). BM was obtained by mixing wastes subjected to some specific preparation processes in equal proportions, while new-AC was produced by pyrolyzing BM chemically activated with KOH. Various techniques such as elemental analysis, BET-surface area (SBET), pore size and volume measurements, pHpzc, FTIR, Boehm titration, and SEM–EDX analysis were employed for the characterization of adsorbents. The findings revealed that new-AC exhibited a greater SBET, carbon content, and more acidic surface (1413 m2/g, 91.9% C, and pHpzc of 6.8) compared to BM (5.32 m2/g, 51.08% C, and pHpzc of 7.8). Adsorption experiments were performed to evaluate the efficiency of each adsorbent, with results compared against a commercial activated carbon (com-AC) for Cr(VI) removal. The optimal conditions for removing 50 mg-Cr(VI)/L were identified as pH 2, 4 g/L dosage, and 30 min contact time for new-AC; pH 2, 5 g/L dosage, and 90 min for com-AC; and pH 2, 20 g/L dosage, and 60 min for BM. The maximum adsorption capacities observed for BM, new-AC, and com-AC were 6.46, 51.55, and 41.67 mg/g of Cr(VI), respectively. The adsorption behavior for all three adsorbents aligned well with the Langmuir isotherm model, and thermodynamic analysis suggested that the adsorption processes were exothermic, spontaneous, and favorable.

Rapid Microwave Irradiation-Enhanced Detoxification and Mineralization of Cr(VI) by FeS2/ZVI Composites

The rapid detoxification and mineralization of Cr(VI) in aqueous environments hold critical importance for emergency response and resource recovery yet remain technically challenging. Herein, we report the synthesis of FeS2/ZVI composites through ethanol-assisted wet ball-milling and their application in Cr(VI) removal under microwave (MW) irradiation. This study systematically investigates the effects of MW irradiation on the removal efficiency of Cr(VI) using FeS2/ZVI composites, with particular focus on key parameters including composite dosage, initial pH, MW temperature, and Cr(VI) concentration. Notably, 1 g/L FeS2/ZVI composites achieved near-complete removal (>99%) of 50 mg/L Cr(VI) within 7 min at a MW irradiation temperature of 333 K, which exhibited 5.9-fold and 13.1-fold superior performance compared to pure pyrite and ZVI, respectively. Additionally, there is a 96.1% reduction in reaction time in comparison to non-MW irradiation system. In real electroplating wastewater samples, Cr(VI) concentration was reduced from 38.93 to 0.42 mg L−1 by MW irradiation-assisted treatment, validating its potential for practical applications in industrial Cr(VI) pollution control. The activation energy determined by fitting the Arrhenius equation showed a 39.7% reduction for the MW-assisted FeS2/ZVI system (16.0 kJ mol−1) compared to conventional thermal heating (from 25.6 kJ mol−1), indicating that MW irradiation induced catalytic enhancement of FeS2/ZVI, thereby lowering the energy barrier for Cr(VI) reduction. Moreover, MW irradiation-assisted processes facilitated the mineralization of reduced Cr(III) to stable spinel FeCr2O4. These findings collectively establish a synergistic mechanism between MW activation and FeS2/ZVI composites, offering innovative pathways for efficient Cr(VI) detoxification and resource recovery from high-strength industrial wastewaters.

Zeolitic imidazolate framework- cellulose loading GR(II)/Cu for efficient Cr(VI) removal over a wide pH range from water: Combined insights of capture performance and potential mechanism analysis.

Zeolitic imidazolate framework- cellulose loading GR(II)/Cu for efficient Cr(VI) removal over a wide pH range from water: Combined insights of capture performance and potential mechanism analysis.

Mechanochemical-Triggered Confined Coordination of Iron-Biomass Composites for Efficient Cr(VI) Reduction Under Circumneutral pH Via Accelerated Electron Extraction.

Green and eco-friendly iron-based materials for efficient Cr(VI) removal have attracted considerable interest, but challenges related to narrow working pH ranges and iron utilization efficiency still remain. Herein, inspired by the hot-spot effect-triggered confined coordination strategy, a biomass-confined iron-based reductant (CMC-GTB/Febm) is designed for Cr(VI) reduction and detoxification. Electron enrichment and confinement on biomass carriers are achieved through electron transfer mediated by coordination interactions between anchored iron species and biomass. Thus, the CMC-GTB/Febm achieved 99% Cr(VI) reduction at circumneutral pH (5-9), with a maximum removal capacity of 180mgg-1. Under iron dosing close to the stoichiometric ratio (Fe/Cr = 3/1), the Cr(VI) removal kinetics and efficiency of CMC-GTB/Febm are 53.2-870.5 and 5.5-48.8 times higher than those of micro- or nano-zero-valent iron (ZVI), respectively. Mechanistic analyses revealed that confined electron transfer is facilitated by coordination interactions between biomass and anchored iron species, which enhanced Cr(VI) reduction. Moreover, biomass-tethered reduced Cr(III) is stabilized by electrostatic adsorption and biomass-Cr(III) coordination, which ultimately detoxifies the phytotoxicity of Cr(VI). The conversion of this strategy to kilogram-scale production and the simulated Cr(VI) removal in real water matrices are confirmed. This study provides a basis for the controlled design and industrial application of environmentally friendly iron-based reductants.

Polyethyleneimine modified cellulose nanofiber microgel for rapid and efficient Cr(VI) removal

Polyethyleneimine modified cellulose nanofiber microgel for rapid and efficient Cr(VI) removal

Biowaste-derived hybrid adsorbent for efficient Cr (VI) removal

Biowaste-derived hybrid adsorbent for efficient Cr (VI) removal

Self-modified iron-based materials for efficient chromium (VI) removal: Efficacy and mechanism.

Self-modified iron-based materials for efficient chromium (VI) removal: Efficacy and mechanism.

Well designed and high efficient noble metal free NiTe2/rGO heterojunction as dual purpose for efficient visible-light photocatalytic H2 evolution and Cr(VI) reduction

Well designed and high efficient noble metal free NiTe2/rGO heterojunction as dual purpose for efficient visible-light photocatalytic H2 evolution and Cr(VI) reduction

Construction of S-scheme heterojunction based on an organic hybrid silver tin selenide with strong affinity to Cr(VI) for efficient photocatalytic Cr(VI) reduction

Construction of S-scheme heterojunction based on an organic hybrid silver tin selenide with strong affinity to Cr(VI) for efficient photocatalytic Cr(VI) reduction

Ultrathin porous nitrogen-doped carbon nanosheets with rich defects for efficient Cr(VI) reduction

Ultrathin porous nitrogen-doped carbon nanosheets with rich defects for efficient Cr(VI) reduction

Constructing thiophene-decorated organic molecular sieves as efficient photocatalysts for removing chromium(vi)

Concisely constructing thiophene-incorporated conjugated microporous polymer photocatalysts for highly efficient Cr(vi) reduction.

Carbon dots with high brightness and stability towards efficient Cr(Ⅵ) and l-arginine sensors

Carbon dots with high brightness and stability towards efficient Cr(Ⅵ) and l-arginine sensors

Efficient photo-assisted reduction of Cr(VI) via activated carbon mediated Z-scheme FeS2/α-FeOOH/C heterojunction: Focusing on molecular oxygen fate and synergetic reduction mechanism

Efficient photo-assisted reduction of Cr(VI) via activated carbon mediated Z-scheme FeS2/α-FeOOH/C heterojunction: Focusing on molecular oxygen fate and synergetic reduction mechanism

Efficient Cr(III) removal from effluent using functionalized Ficus benghalensis and Bambusa vulgaris bio-adsorbents

Efficient Cr(III) removal from effluent using functionalized Ficus benghalensis and Bambusa vulgaris bio-adsorbents

Amino-Functionalized Metal-Organic Framework-Mediated Cellulose Aerogels for Efficient Cr(VI) Reduction.

Industrialization activities have increased the discharge of wastewater that is polluted with hexavalent chromium (Cr(VI)), posing risks to ecosystems and humans. The photocatalytic reduction of Cr(VI) is viewed as a promising method for the removal of Cr(VI) species. However, developing photocatalysts with the desired catalytic activity, recyclability, and reusability remains a challenge. Herein, a composite aerogel was designed and fabricated with a Ti-based metal-organic framework (MIL-125-NH2) and carboxylated nanocellulose. MIL-125-NH2 presents a strong visible-light response, and the interactions between the amino groups of MIL-125-NH2 and the carboxyl groups of cellulose produce a strong interface affinity in the composites. The as-prepared aerogels exhibited a micro/macroporous structure. At an optimal MIL-125-NH2 loading of 55 wt%, the MC-5 sample showed a specific surface area of 582 m2·g-1. MC-5 achieved a photocatalytic Cr(VI) removal efficiency of 99.8%. Meanwhile, the aerogel-type photocatalysts demonstrated good stability and recycling ability, as MC-5 maintained a removal rate of 82% after 10 cycles. This work sheds light on the preparation of novel photocatalysts with three-dimensional structures for environmental remediation.

Highly efficient reduction of Cr(VI) from industries sewage using novel biomass-driven carbon dots modified TiO2 under sunlight

Highly efficient reduction of Cr(VI) from industries sewage using novel biomass-driven carbon dots modified TiO2 under sunlight

Preparation of Poly(allylamine Hydrochloride) Grafted Porous Boron Nitride Fibers for Efficient Cr(VI) Adsorption from Aqueous Solution.

Cr(VI) pollution poses great harm to the cyclic utilization of groundwater and surface water resources. Efficient adsorbent materials have great potential to change this situation and assist in the restoration of ecosystems. This work chooses porous boron nitride fibers (pBN) with stable physical and chemical properties as the matrix, 3-aminopropyltriethoxysilane (APTES) as the coupling agent, and uses a one-step crosslinking method to graft poly(allylamine hydrochloride) (PAH) onto pBN, forming pBN-AS@PAH with fascinating Cr(VI) adsorption capacity. PAH is uniformly covered and modified on the surface of pBN, and the composite with high specific surface area (383.33 m2/g), large pore volume (0.37 cm3/g), and abundant amino groups. Its equilibrium adsorption capacity for Cr(VI) can reach up to 123.32 mg/g, and the adsorption behavior follows the quasi second-order kinetic model and Langmuir model, indicating the chemical adsorption process of monolayer. The adsorption style belongs to a spontaneous exothermic process and has the optimal adsorption effect at a pH of ~2. Additionally, after cycling for 5 times, the decrease rate of adsorption capacity is less than 10 %, showing an excellent reusability.

Transformation of iron-minerals from natural aquifer media by sulfate-reducing bacteria: Behavior, mechanism, and Cr(VI) removal

Transformation of iron-minerals from natural aquifer media by sulfate-reducing bacteria: Behavior, mechanism, and Cr(VI) removal

In-situ and ex-situ preparation of Bi2S3 on the BiVO4/TiO2 to construct Bi2S3/BiVO4/TiO2 heterojunction for efficient Cr(VI) reduction

In-situ and ex-situ preparation of Bi2S3 on the BiVO4/TiO2 to construct Bi2S3/BiVO4/TiO2 heterojunction for efficient Cr(VI) reduction

Coconut shells based MrGO@CMC adsorbent for the chromium (VI) ion removal from contaminated water through batch adsorption method

Coconut shells based MrGO@CMC adsorbent for the chromium (VI) ion removal from contaminated water through batch adsorption method