Controlled synthesis of Fe3O4/MnO2 (3 1 0)/ZIF-67 composite with enhanced synergetic effects for the highly selective and efficient adsorption of Cu (II) from simulated copperplating effluents.

This study designed a composite material with internal synergistic effects among multiple components to achieve highly selective adsorption of Cu (II). Through controlled synthesis, the Fe3O4/MnO2(3 1 0)/ZIF-67 composite was successfully fabricated, leading to significant improvement in adsorption selectivity, capacity, and adsorption rate. The experimental results showed that the composite is of outstanding selectivity in the adsorption of Cu (II), with a partition coefficient K of Cu (II) that was 2.2-5.3 times higher than that of other coexisting ions. Moreover, the composite exhibited a remarkable adsorption capacity of 1261.0 mg g-1 and a fast adsorption rate of 840.7 mg g-1 h-1 at 298 K. Additionally, its magnetic property facilitated easy separation from wastewater, thereby enhancing its potential for commercial applications. The synergetic effect mechanism was analyzed through characterizations and DFT calculations. Furthermore, the recyclability of the composite was investigated, which showed that after seven cycles, the adsorption efficiency remained at 85% of its initial efficiency. It can be concluded that Fe3O4/MnO2(3 1 0)/ZIF-67 has potential to address challenges posed by heavy metal pollution in copperplating effluents.

Adsorptive removal of organic dyes via porous materials for wastewater treatment in recent decades: A review on species, mechanisms and perspectives.

Organic dyes, a type of high toxic and carcinogenic chemicals that present severe threats to human and aquatic life, are the most commonly seen organic pollutants in wastewater of industries such as textile, rubber, cosmetic industry etc. Various techniques for the removal of dyes are compared in this review. Adsorption has proven to be a facile and promising approach for the removal of dyes in wastewater. This work focuses on the latest development of various porous materials for the adsorption of organic dyes. The characteristics, functionalization and modification of different porous materials are also presented. Furthermore, adsorption behaviors and mechanism of these adsorbents in the adsorption of organic dyes are critically reviewed. Finally, challenges and opportunities for future research in the development of novel materials for the highly efficient removal of dyes are proposed.

A high-performance histidine-functionalized MWCNT-GONR/Co-Ni LDH flower cluster structural composite via a microwave synthesis for supercapacitors.

A flower cluster structural histidine-functionalized multi-walled carbon nanotube-graphene oxide nanoribbon/Co-Ni LDH (His-MW/LDH) composite was synthesized via the microwave method. In this study, we used His-MW as a carbon material to synthesize the electrode because it not only has the properties of MWCNT-GONR (MW) but also completes the N doping process due to the addition of histidine. His-MW adhered to the LDH flower cluster, and the radius of the composite was found to be nearly 1 µm. The synergistic effects of His-MW and LDH could effectively increase the specific surface areas and conductivity of the composite, thereby endowing it with high specific capacitance (1674 F g-1) and admirable cycling stability (83.33% capacitance retention). Moreover, we assembled an asymmetric supercapacitor, and it possessed 39.47 W h kg-1 at 0.80 kW kg-1 as well as prominent cycling stability (93.81% capacitance retention). This study proves the feasibility of synthesizing the histidine-functionalized carbon derivative/LDH composite by the microwave method. Moreover, we are optimistic that the electrode material can be extensively used in supercapacitors because of its splendid electrochemical properties and facile synthesis.

Microwave synthesis of histidine-functionalized graphene quantum dots/Ni-Co LDH with flower ball structure for supercapacitor.

A flower ball-like histidine-functionalized graphene quantum dots/Ni-Co LDH (His-GQD/LDH) composite is synthesized via microwave method. The GQDs are uniformly interspersed on LDH surface and the radius of flower balls is approximately 200 nm. The synergistic effect of His-GQD and LDH can signally increase the specific surface areas and conductivity of the composite, thus endowing the composite high specific capacitance (1526 F g-1) and an admirable cycling stability (82.36% capacitance retention). Moreover, we have manufactured a supercapacitor employing His-GQD/LDH and active carbon (AC) as positive/negative electrodes. The device exhibits the maximum energy of 48.89 W h kg-1 at 0.80 kW kg-1, as well as prominent cycling stability (91.13% capacitance retention). This work provides a practicle experimental method of synthesizing hybridizing histidine-functionalized carbon derivatives with LDH by microwave synthesis. Meanwhile, we are optimistic to believe that the electrode material can be extensively applied for supercapacitor because of its splendid electrochemical properties and facile synthesis.

Evaluation of activated carbon synthesized by one-stage and two-stage co-pyrolysis from sludge and coconut shell.

Waste biomass and sewage sludge were used to obtain an adsorbent material with excellent performance qualities by adopting a KOH activation process via one-stage (ACone) or two-stage (ACtwo) co-pyrolysis. The main purpose of this work was to investigate the effects of both methods in terms of the physicochemical properties and adsorption capacities for methylene blue (MB). Textural analyses revealed that the surface area (Stot= 683.82 m2/g) and total pore volume (Vtot= 0.72 cm3/g) of ACtwo were more than two-fold compared with ACone (Stot= 285.33 m2/g; Vtot= 0.35 cm3/g). Thus, two-stage co-pyrolysis produced activated carbon with increased porosity, which was favorable for MB adsorption. Nevertheless, the intensity of the surface functional groups of ACtwo was weaker than for ACone, which could be due to the pore-forming mechanism. Two-stage co-pyrolysis increased the yield and aromaticity of activated carbon, but sufficient activation caused more functional groups to decompose. For the adsorbate MB, the maximum adsorption capacity of ACtwo (602.80 mg/g) was more than five-fold greater than that of ACone (101.88 mg/g), due to its excellent porosity properties. Furthermore, the interactions of MB molecules with activated carbon were via hydrogen bonds and electrostatic attraction. The adsorption process of MB onto activated carbon was accurately described by the pseudo-second-order kinetic model. Adsorption equilibrium evaluated Langmuir isotherms demonstrated that MB formed a monolayer by adsorption onto the activated carbon. Adsorption thermodynamics was used to investigate the influence of temperature on the adsorption process. Thermodynamic parameters indicated that MB adsorption onto activated carbon was spontaneous and endothermic. In conclusion, our results showed that two-stage co-pyrolysis improves the adsorption capabilities of activated carbon, so achieving better economic value from waste materials.