Hexavalent Chromium Ions Research Articles

Luminescence quenching of Ru(II)-diimine complexes with Cr(VI) ions: Steady-state and time-resolved studies

Luminescence quenching of [Ru(bpy)(CN)4]2−, [Ru(phen)(CN)4]2−, [Ru(bpy)3]2+ and [Ru(phen)3]2+ by hexavalent chromium ion in aqueous media were investigated by steady-state and time-resolved measurements. Effect of pH on the luminescence quenching process is also investigated. It has been found that luminescence changes due to the interaction of all Ru(II) complexes with Cr(VI) ions were high at pH values less than or equal to 5.0 and negligible at pH ≥ 8.0. The experimental data of the quenching process were analyzed using Stern–Volmer (S–V) equations. The steady state luminescence emission data shows an upward curvature, indicating that the quenching is preceded by both dynamic and static quenching. For all studied complexes, the lifetime of the excited 3MLCT state decreases with increasing Cr(VI) concentration implying that the diffusion is mainly responsible for the quenching process. The Stern–Volmer dynamic quenching constants (KD) and the bimolecular quenching rate constant for the quenching process (kq) were calculated by applying the Stern–Volmer equation to the luminescence decay data. The bimolecular quenching rate constants (Kq) were found to increase in the order [Ru(bpy)(CN)4]2− < [Ru(phen)(CN)4]2− < [Ru(phen)3]2+ < [Ru(bpy)3]2+ which correlates will with the oxidation potentials of Ru(II) complexes. The association constants for Ru(II)-Cr(VI) system were calculated using the Benesi-Hildebrand equation and found to be 3.0 × 103, 2.5 × 103, 1.2 × 103, 7.1 × 103 M−1 for [Ru(bpy)(CN)4]2−, [Ru(phen)(CN)4]2−, [Ru(bpy)3]2+ and [Ru(phen)3]2+ respectively, which is interpreted in terms of the dynamic (diffusion) and the sphere of action (static) quenching models.

Bio-inspired one-step structure adjustment and chemical modification of melamine foam toward highly efficient removal of hexavalent chromium ions

• Polydopamine (PDA)-decorated melamine foam (MF) was successfully achieved. • Morphology of PDA on the MF skeleton was tailored. • The MF-PDA sample showed high adsorption capacity toward Cr(VI). • 53.7% of Cr(VI) was reduced to Cr(III) during the adsorption. • Mechanisms based on protonation effect and charge attraction were proposed. Providing highly efficient and economical adsorbents is the prerequisite for the heavy metal ions removal from wastewater through the adsorption method. Herein, the polydopamine (PDA)-coated melamine foam (MF) skeleton (MF-PDA) was achieved through the bio-inspired functionalization method. The results showed that the smooth surface of MF skeleton was successfully coated by PDA nanoparticles, leading to the changes of surface roughness and chemical features of MF skeleton. Studies on the adsorption behaviors toward highly toxic Cr(Ⅵ) by the MF-PDA samples showed that the MF-PDA samples had the good removal ability and the maximum adsorption capacity was about 240 mg/g at pH value of 2. In addition, the MF-PDA sample also showed high adsorption selectivity, high desorption ability and good reusability. Further analysis found that the coated PDA had a strong reduction effect on Cr(Ⅵ), and about 53.7% toxic Cr(Ⅵ) was reduced to low-toxic Cr(III) during the adsorption. Although PDA decoration method has already been used to assist the secondary modification or to enhance the modification efficiency of the other functionalization method, this work clearly declares that PDA exhibits great role in removing Cr(Ⅵ) and the MF-PDA sample is a promising adsorbent for removing highly toxic Cr(Ⅵ) from sewage.

Enhanced removal of hexavalent chromium from aqueous solution by functional polymer-wrapped gamma-alumina composite adsorbent

Here we reported a novel xanthated chitosan-entrapped gamma-alumina (XCSA) composite sorbent that presents effective removal toward toxic hexavalent chromium ions [Cr(VI)] from water. The samples were characterized by FTIR, SEM-EDS, XRD, TGA, and XPS. Batch sorption experiments were performed to investigate the influences of component ratio, initial solution pH, and competing ions on the Cr(VI) removal. An adsorption-coupled reduction mechanism controlled the Cr(VI) removal processes, in which xanthation groups played a key part. The sorption process revealed that ∼ 65% Cr(VI) (50 mg/L) was adsorbed within 5 min, and kinetic data fitted well with the pseudo-second-order model. The sorption isotherm data fitted well with Freundlich model, and the experimental maximum sorption capacity for Cr(VI) by XCSA-1.0 (with the alumina-to-polymer mass ratio of 1:1) was ∼ 110.5 mg/g. In addition, XCSA-1.0 expressed the good anti-interference ability of the competing ions. Moreover, the exhausted adsorbent, which could be regenerated by 1.0 M KCl solution, exhibited good reusability after five cycles. Overall, this study shows XCSA as a promising sorbent for anionic heavy metal removal from water. • Xanthated chitosan wrapping γ -alumina sorbents were prepared for Cr(VI) removal. • Fast kinetics of adsorption (within 120 min) over this composite adsorbent. • A better adsorption capacity ( ∼ 110.5 mg/g) than many other similar sorbents. • An adsorption-coupled reduction mechanism controlled Cr(VI) removal processes.

Rational construction of Ag3PO4/WO3 step-scheme heterojunction for enhanced solar-driven photocatalytic performance of O2 evolution and pollutant degradation

Heterojunction engineering has been regarded as a promising strategy to sufficiently utilizing photogenerated charge carriers, thus benefiting the improvement of photocatalytic performance. Herein, Ag3PO4/WO3 S-scheme heterojunction was synthesized via a simple deposition-precipitation process, and its photocatalytic activity was evaluated by monitoring water splitting and pollutant degradation under visible light. As a result, Ag3PO4/WO3 with optimized ratio photocatalyst showed enhanced photocatalytic activity in oxygen production (306.6 μmol·L-1·h−1) relative to pure Ag3PO4 (204.4 μmol·L-1·h−1). Additionally, it also exhibits rapid toxicity elimination efficiency over hexavalent chromium ions (Cr6+) and ciprofloxacin (CIP) with degrading rate of 72% and 83% within 30 min, respectively. According to a series characterization, a possible S-scheme photocatalytic mechanism of Ag3PO4/WO3 was demonstrated in detail, which endowed the heterojunction with strong redox abilities to provide powerful diving force towards the photocatalytic reaction. This work presents an innovative perspective to construct Ag3PO4-based S-scheme heterojunctions for boosting photocatalytic performance for various applications.

Synthesis and adsorption potential of an organic–inorganic-based hybrid nanomaterial (PANI-Al2O3)

Recently, the inorganic–organic-based hybrid nanocomposite materials have been successfully utilized in the removal of the inorganic contaminants from the aqueous system. This study deals with the synthesis, characterization, and adsorption applications of low-cost and efficient polyaniline-Al2O3 (PANI-Al2O3)-based material. The freshly synthesized PANI-Al2O3 was analyzed using P-XRD, FE-SEM, FT-IR, and EDX methods. This material has been successfully used in the adsorptive removal of divalent lead and hexavalent chromium ions from synthetically prepared waste water. The adsorption efficiency of PANI-Al2O3 for Pb (II) and Cr (VI) ions was recorded as 93.1% (at pH 6) and 76.3% (at pH 2), respectively. The adsorption capacities (Qmax) have been evaluated from Langmuir model as 9.901 and 12.048 mg/g for Pb (II) and Cr (VI) ions under our laboratory scales. Pseudo second-order rate constants of Pb (II) and Cr (VI) ions were found as 45.45 and 29.15 g mg−1 min−1, respectively.

Micro-mesoporous modified activated carbon from corn husks for removal of hexavalent chromium ions

Modified activated carbon sorbents (ACP-Zn and ACP-Zn-Fe) had been prepared from the activation of corn husks precursor to increase the chemical activity of the resulting adsorbents by increasing the number of active functional groups and generation of micro-mesoporous structures. Fourier transform infrared (FTIR) assessed the acidic surface properties of the prepared activated carbons that is due to the presence acidic functional groups such as –OH and –COOH which improves the removal efficiency of the produced sorbents. Textural characteristics revealed the generation of micro-mesoporous structures in ACP–Zn and ACP-Zn-Fe. Thus the combination of H3PO4 with Zn or Zn–Fe could enhance the mesoporosity with a considerable decrease in the adsorption of nitrogen. However, the formation of mesopores might be attributed to the template-like effects of the obtained Zn- of Zn-Fe compounds inside the carbon structure. These structures were employed as sorbents for removal of hexavalent chromium Cr(VI) ions from its aqueous solutions, and the removal efficiency reached ~ 86% for ACP-Zn-Fe and ~ 82% for ACP-Zn. The kinetic modeling studies revealed that the sorption process follows the pseudo-second-order model which indicates that the mechanism of process is chemisorptions. Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models were used to express the experimental data. The isotherm modeling studies revealed that the sorption process was fit with both Freundlich and Langmuir models with maximum capacity 24.8 and 30.3 mg/g for ACP-Zn and ACP-Zn-Fe, respectively.

Synthesis and Study of Magnesium Ferrite/Reduced Graphene Oxide (MgFe2O4/rGO) Nanocomposite Electrodes to Electrochemical Removal of Hexavalent Chromium Ion from Wastewater

Synthesis and Study of Magnesium Ferrite/Reduced Graphene Oxide (MgFe2O4/rGO) Nanocomposite Electrodes to Electrochemical Removal of Hexavalent Chromium Ion from Wastewater

Composation of Polyaluminum Chloride with Hydroxyapatite and Its Application for Separation of Hexavalent Chromium Ions

Ch romium is the dominant heavy metal in liquid waste from the leather tanning industry, wood preservation and textile processing. Generally c h romium waste is found as trivalent and he x a v a l en t chromium ions. Hexavalent chromium ion is dangerous for humans because of its carcinogenic nature, which can lead to skin irritation, lung cancer, kidney and stomach disorders. Coagulation-flocculation (CF) is a method used to reduce hexavalent chromium ion levels. Polialuminum chloride (PAC) has been widely used in water treatm ent using the CF method. Unfortunately, however, the PAC stability is poor, the coagulation efficiency is low, and the floc formation time is slow. In addition, PAC can produce Al3+ which is toxic in processed water. But its toxicity can be overcome by adding donor ligands that contain oxygen such as hydroxides, carboxylic acids and phosphates, such as hydroxyapatite (HA). In addition, the addition of HA with the optimum composition and pH at PAC can increase the performance of PAC. This study aims to optimize the PAC/HA combination at various pH so as to reduce the concentration of hexavalent chromium ion, controlled by UV-VIS spectroscopy. The highest reduction in Cr (VI) ion content was obtained by PAC, but the highest stability was obtained by the composition of PAC/HA 4: 6.

Recyclable Functionalized Material for Sensitive Detection and Exceptional Sorption of Hexavalent Chromium and Permanganate Ions with Biosensing Applications.

Environmental remediation with a single platform for selective sensing and removal of toxic analytes with recyclability of the material has always been a desirable system for sustainability. However, materials comprising all the abovementioned advantages are rarely known for oxoanions. We herein developed a fluorogenic napthalimide-based functionalized mesoporous silica material (SiO2@NBDBIA) as a signaling and remediation system for oxoanions (CrO42-, Cr2O72-, and MnO4-) from a pool of several anions. The fluorescence quenching of the SiO2@NBDBIA material in the presence of CrO42-, Cr2O72-, and MnO4- ions gives the limit of detection (LOD) values of 6.23, 25.2, and 20.32 ppb, respectively, which are well below the maximum contaminant level demarcated by the United States Environmental Protection Agency. The maximum adsorption capacities of the material for the abovementioned oxoanions are found to be 352, 363, and 330 mg/g, respectively, which are well above those mentioned in the literature reports. Contrary to the literature-dominated irreversible ion-exchange mechanism, the reversible hydrogen-bonded binding of the material with the oxoanions leads to the recyclability of the material easily, which is very rare in the literature. The DFT calculations were performed to examine the interactions between the material and oxoanions. For real applications, this material was also used as a fluorescence probe to detect these oxoanions in the actual water samples, and more interestingly, used as a biosensing probe for these oxoanions in the living organism Artemia salina through fluorescence imaging. Thus, the SiO2@NBDBIA material is a unique example of recyclable material for detecting and remediating oxoanions.

Determination of Cr(VI) based on the peroxidase mimetic catalytic activity of citrate-capped gold nanoparticles.

Highly negatively charged gold nanoparticles (AuNPs) are shown to havestrong simulated oxidase activity and effectively boosted the oxidation of enzyme substrate 3,3',5,5'-tetramethylbenzidine (TMB) by hexavalent chromium ion Cr(VI), resulting in the formation of oxidation product with blue color. Based on this, a facile colorimetric assay was developed to detect Cr(VI) at a range 0.008~0.156mg/L with r= 0.996. The detection limit was estimated to be 0.52μg/L. In addition, the colorimetric assay showed high selectivity against 28 other interfering ions. It was performed at room temperature and required about half an hour including the preparation of AuNPs. The assay was successfully applied to the determination of Cr(VI) in spiked water samples, and recoveries in the range 95.00-105.40% were obtained. This work paves a way for design of high performance sensor based on highly active nanozymes and also provides an extremely practical analytical tool for the monitoring of Cr(VI) in the environment.

Adsorption of Hexavalent Chromium and Divalent Lead Ions on the Nitrogen-Enriched Chitosan-Based Activated Carbon.

Optimizing the physicochemical properties of the chitosan-based activated carbon (Ch-ACs) can greatly enhance its performance toward heavy metal removal from contaminated water. Herein, Ch was converted into a high surface area (1556 m2/g) and porous (0.69 cm3/g) ACs with large content of nitrogen (~16 wt%) using K2CO3 activator and urea as nitrogen-enrichment agents. The prepared Ch-ACs were tested for the removal of Cr(VI) and Pb(II) at different pH, initial metal ions concentration, time, activated carbon dosage, and temperature. For Cr(VI), the best removal was at pH = 2, while for Pb(II) the best pH for its removal was in the range of 4–6. At 25 °C, the Temkin model gives the best fit for the adsorption of Cr(VI), while the Langmuir model was found to be better for Pb(II) ions. The kinetics of adsorption of both heavy metal ions were found to be well-fitted by a pseudo-second-order model. The findings show that the efficiency and the green properties (availability, recyclability, and cost effectiveness) of the developed adsorbent made it a good candidate for wastewaters treatment. As preliminary work, the prepared sorbent was also tested regarding the removal of heavy metals and other contaminations from real wastewater and the obtained results were found to be promising.

Photocatalytic Reduction of Hexavalent Chromium Ions from Aqueous Solutions Using Polymeric Microfibers Surface Modified with ZnO Nanoparticles

Photocatalytic Reduction of Hexavalent Chromium Ions from Aqueous Solutions Using Polymeric Microfibers Surface Modified with ZnO Nanoparticles

Zirconium oxide intercalated sodium montmorillonite scaffold as an effective adsorbent for the elimination of phosphate and hexavalent chromium ions

The presence of oxyanions such as hexavalent chromium (Cr(VI)) and phosphate in water resources posing significant threat to both environment and human beings. Therefore, the present investigation focused on the elimination of phosphate and Cr(VI) anions from water by employing zirconium oxide intercalated sodium montmorillonite (ZrO2-NaMMT@700) composite as an adsorbent. The prepared ZrO2-NaMMT@700 composite was characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyzer. The surface characterization results confirmed the successful intercalation of ZrO2 nanoparticles into NaMMT. The ZrO2-NaMMT@700 composite showed better and rapid removal for phosphate and Cr(VI) anions with the maximum adsorption capacity of 64.57 and 52.46 mg/g, respectively. The adsorption studies suggested that removal of phosphate and Cr(VI) was mainly driven by the electrostatic attraction and electrostatic attraction coupled reduction, respectively. Besides, the obtained phosphate and Cr(VI) adsorption data were well described by the Langmuir isotherm and pseudo-second-order kinetic models. Furthermore, the exhausted ZrO2-NaMMT@700 composite could be easily regenerated and reused in subsequent adsorption experiments. Overall, due to the easy synthesis, excellent adsorption capacity, and regeneration ability, the prepared ZrO2-NaMMT@700 composite could be served as a potential candidate for the removal of phosphate and Cr(VI) anions.

Regeneration of Activated Carbon Sutured Hexavalent Chrome

In order to prevent a simple pollution transfer and for the purpose of valorization of the process of activated carbon treatment, this one, saturated with pollutants should not increase the pollution mass of household waste. Indeed, an adsorbent offers a real interest only if it can be easily regenerated. This work addresses to the becoming the activated carbon after being saturation with hexavalent chromium. The activated carbon should not be stored directly, since the acid rain waters might leach some heavy metals. This would contaminate the soil and water resources. For this, it should be treated after use and returned to its original structure and chemical composition for an eventual future use with a good yield of re-adsorption. Within this work, the use of a base (KOH) has recovered an amount of hexavalent chromium retained by the activated carbon CAB. This one, regenerated was again used to secure the hexavalent chromium ions during several cycles. Regeneration test results have shown that the efficacy of CAB remains almost constant during the first four cycles of reuse and then decreases during the fifth cycle.

Defects coordination triggers red-shifted photoluminescence in carbon dots and their application in ratiometric Cr(VI) sensing

Hexavalent chromium ion (Cr(VI)) is one of the most severe environmental nonbiodegradable pollutants. Considering its high biological toxicity, it is of great significance to establish a method for Cr(VI) analysis with high sensitivity and reliability. Therefore, a simple and sensitive ratiometric sensor is developed according to the coordination between Cr(VI) and carbon dots (CDs). In the presence of Cr(VI), the original CDs photoluminescence (PL) emission at 445 nm was significantly shifted to 565 nm and gradually intensified. The coordination mechanism was investigated, the results indicated that the dual-amino groups at ortho-position of benzene ring is critical for this coordination. Under the optimal condition, a good linear relationship between the concentration of Cr(VI) and the PL intensity ratio I565/I445 was obtained from 120 nM to 200 µM, with a low detection limit of 37 nM. Moreover, this method is applied into real water samples analysis with a high quality.

Selective and efficient sequestration of Cr(VI) in ground water using trimethyloctadecylammonium bromide impregnated on Artemisia monosperma plant powder

BackgroundBiosorption method for Cr(VI) removal from domestic and industrial wastewater is widely desirable technicality due to its high efficiency, natural affinity, selectivity, easily operation, low costs and eco-friendly procedures. The presented work demonstrates the sequestration of hexavalent chromium ion, Cr(VI) from contaminated water by the biosorbent Artemisia monosperma (AM) powder modified by trimethyloctadecylammonium bromide (TOAB). MethodsAnalytical tools of XRD, FTIR, SEM, EDS, TGA and XPS were used from one side to characterize the developed modified biosorbent TOAB@AM and from the other side to investigate the Cr(VI) adsorption. Operational parameters of pH, adsorbent dose, contact time, coexisting ions and temperature that affect adsorption process were optimized. Significant FindingsAdsorption kinetics emerges the best linearity when applying the pseudo-second-order model referring to the chemisorption assumption in controlling sorption process of TOAB@AM biosorbent and Cr(VI) ions. Adsorption isothermal results are distinctly well fitted with Langmuir correlation. Furthermore, adsorption thermodynamics reveals the spontaneity and exothermic modality in adsorbing Cr(VI) onto TOAB@AM biosorbent with less randomness behavior. The optimal operational conditions for Cr (VI) removal are pH = 3; 0.1g dose of TOAB@AM; and 40 min contact time that result in adsorption capacity of Cr (VI) about 36.9 mg/g. Merits of low cost, high selectivity, and adsorptive potency of the novel TOAB@AM biosorbent towards Cr(VI) ions makes it a worthy alternative for remediating water sources from Cr(VI) contaminates within a facile and fast avenue.

Polyvinylсhloride‐based anion exchanger for efficient removal of chromium (VI) from aqueous solutions

AbstractChemical modification of plasticized polyvinylchloride with polyethylenepolyamine leads to anion exchange resin (PPE‐1). Different characterization techniques, such as XRD, FTIR, and SEM of PPE‐1 anion exchanger revealed weak base amino groups as well as macroporous structure morphology. PPE‐1 turned out effective to remove hexavalent chromium ions from aqueous media. Corresponding adsorption kinetics best fit the pseudo‐second order model that followed a Freundlich isotherm. In the case of hexavalent chromium ions, the maximum adsorption capacity of PPE‐1 was 218.4 mg/g. Thermodynamic data revealed spontaneous endothermic processes and a chemisorption reaction. In addition, results show that the anion exchanger (PPE‐1) has 98% for removing hexavalent chromium ions containing from wastewater.

DABCO Derived Nitrogen-Doped Carbon Nanotubes for Oxygen Reduction Reaction (ORR) and Removal of Hexavalent Chromium from Contaminated Water.

Though chemically-derived reduced graphene oxide (CDG) from graphite oxide (GO) precursors is a widely practiced procedure for the large-scale production of graphene, the quality and quantity of thus obtained CDG is dependent on the reduction strategy used. In this work, we report an all-solid-state, residue-free, microwave process for the reduction of graphene oxide and subsequent growth of carbon nanotube ‘separators’ from a single precursor, namely DABCO (1,4-diazabicyclo[2.2.2]octane). The utility of our newly developed technique in efficiently and effectively reducing graphene oxide and in growing nitrogen-doped carbon nanotubes via catalysts like palladium and iron into unique mesoporous, 3-D hierarchical carbon nanostructures is demonstrated. The applicability of the thus obtained palladium embedded in Pd@NCNT-rGO nanoarchitectures for the oxygen reduction reaction (ORR) is investigated. When carbon fiber (CF) was used as the substrate, three-dimensional Fe@NCNT-CF were obtained, whose capability as versatile adsorbents for hexavalent chromium ion removal from contaminated waters was also demonstrated.

Cerium phosphate polypyrrole flower like nanocomposite: A recyclable adsorbent for removal of Cr(VI) by adsorption combined with in-situ chemical reduction

The present investigation aims to remove Cr(VI) by flower like Cerium Phosphate Polypyrrole nanocomposite material (CePO4-PPY). The material was synthesized by in situ oxidative polymerization method and characterized by FTIR, Raman, XRD, XPS, Zeta potential, N2 adsorption–desorption isotherms, and TGA-DTA analysis. Field emission scanning electron microscopy and transmission electron microscopy images revealed the flower-like morphology of the synthesized nanocomposite. Meanwhile, the fabrication of polypyrrole on cerium phosphate nanoparticles provided a plentiful of active adsorption sites to interact with hexavalent chromium ions. The Cr(VI) adsorption followed the pseudo-second-order kinetic and Langmuir isotherm model showing a high adsorption capacity of 117.78mgg−1 at room temperature at lower pH. The high tolerance capacity of CePO4-PPY in the presence of other co-anions makes it a highly efficient adsorbent. The adsorption dynamic study demonstrated that the rate-determining step was controlled by surface diffusion, pore diffusion, and film diffusion. XPS spectra confirmed the simultaneous adsorption of Cr(VI) and in situ chemical reduction to Cr(III). Regeneration studies illustrated the efficiency of more than 80%, even after five cycles. Therefore, CePO4-PPY nanocomposite could be a unique alternative to act as a promising adsorbent for the effective treatment of Cr(VI) containing wastewater.

NiCo-layered double hydroxide/g-C3N4 heterostructures with enhanced adsorption capacity and photoreduction of Cr(VI)

Photo-catalytic reduction of highly toxic Cr(VI) using graphitic carbon nitride (g-C3N4) based photocatalysts under visible light irradiation condition has been attracting considerable attention recent years. Here, we report the development of heterostructured NiCo-layered double hydroxides (LDHs) grown horizontally on g-C3N4 nanosheets with different degrees of crystallinity (amorphous to crystalline), NiCoLDH/g-C3N4, with high photocatalytic activity for the reduction of toxic hexavalent chromium ions (Cr(VI)) as well as high adsorption capability for congo red (CR) photodegradation under visible light irradiation. The presence of NiCoLDH nanoparticles promotes the adsorption of the anionic pollutants while g-C3N4 in the heterostructure promotes fast photodegradation of CR and reduction of Cr(VI). The NiCoLDH/g-C3N4 composite prepared using amorphous-crystalline g-C3N4 homojunctions shows the best adsorption performance. The kinetic data demonstrates improved correlation coefficient for the pseudo-second-order (R2 > 0.99) and Freundlich isotherm model. The NiCoLDH/g-C3N4 composite shows an improved separation efficiency of photogenerated electron and hole pairs, leading to its improved Cr(VI) adsorption and photo-reduction performance. The monolayer adsorption capacities of CR and Cr(VI) of the NiCoLDH/g-C3N4 heterostructured composite can be as high as 1100 and 46 mg/g at 30 °C, respectively. This work provides new perspectives for the development of highly efficient g-C3N4-based composite photocatalysts for wastewater treatment related applications.