| Excessive amounts of toxic pollutants,such as dyes,have been seriously threatening the ecosystem and human health.Among the developed treatment methods,adsorption and photocatalysis techniques have gained increasing popularity because of their simplicity,low cost,and environmental friendliness.Adsorption and photocatalytic performance,such as capacity and rate,are primarily influenced by the shape and surface characteristics of the appropriate adsorption materials.Large pore sizes not only help to improve adsorption and photocatalytic efficiency but also give a pathway to utilize the specific area.In general,a large surface area favors boosting the removal capacity.As a result,developing low-cost and high-efficiency adsorbents for high-performance dye removal and promoting sustainable development in society is of major scientific importance.Ni/Mg/Al layered double hydroxide has been extensively studied as a high-performance adsorbent.However,developing high surface area and appropriate pore size Ni/Mg/Al LDH to further boost adsorption capacity and adsorption rate and then expanding the practical applications in wastewater treatment remains a significant problem.The goal of this work is to design and produce Ni/Mg/Al LDHs as a high-performance adsorbent and photocatalyst for the removal of hazardous dyes such as methyl orange,Congo red,and methylene blue by optimizing pore characteristics.A variety of Ni/Mg/Al LDHs with varying morphologies were synthesized by adjusting the nucleation and growth conditions of the precursors as well as the calcined conditions.In addition,employing MO,CR,and MB dyes as adsorbed probes,the associated adsorption and photocatalytic performance,behavior,and the relationship between structure and performance were carefully examined.The following are the main points of this work:(1)A basic urea technique was successfully used to synthesize Mg/Al-Layered double hydroxides(Mg/Al LDHs).,which were then calcined at 400°C to form Mg/Al Layered double oxides(Mg/Al LDOs).To reconstruct LDHs,Mg/Al LDOs were fabricated with different feeding ratios of Ni by co-precipitation method.After synthesis,the Ni/Mg/Al-layered double hydroxides(NMA-LDHs)with 20%and 30%Ni(S1 and S2)were roasted at 400°C and transformed into corresponding Ni/Mg/Al-layered double oxides(NMA-LDOs)(S1a and S2b),respectively.The physiochemical properties of synthesized samples were also evaluated by various characterization techniques such as X-ray diffraction(XRD),Scanning electron microscopy(SEM),Energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared(FTIR),and Brunauer,Emmett and Teller(BET).According to BET analysis,S2b has the highest BET surface area of 78m~2/g.This notable characteristic is accompanied by a mesoporous structure.The adsorption behavior of MO onto the synthesized samples was evaluated in batch adsorption mode under varying conditions of contact time,adsorbent quantity and solution p H.As the dosage amount increased from 0.01 g to 0.04 g,the removal percentage of MO dye also increased form 83%to 90%for S1,84%to 92%for S1a,77%to 87%for S2 and 93%to 98%for S2b,respectively.For all of the samples,the adsorption kinetics was well described by the pseudo-second order kinetic model.The equilibrium adsorption data were well fitted to both Langmuir and Freundlich models for MO.Finally,three adsorption-desorption cycles,show that NMA-LDHs and NMA-LDOs have greater adsorption and reusability performance for MO dye signifying that the design and fabrication strategy can facilitate the application of the natural hydrotalcite material in water remediation.(2)Montmorillonite-modified Ni/Mg/Al ternary LDHs(NMA-MMT-LDHs)were synthesized using a simple hydrothermal method.Many characterization methods,XRD,SEM,FTIR,and BET,were used to assess the physiochemical properties of the produced analytes.CR and MB were utilized as model dyes to treat textile waste with the synthesized analytes.The BET analysis reveals that S4-MMT exhibits the highest surface area at 145.6 m~2/g and showcases a distinctive nano-flower structure.This can be ascribed to the formation of additional layers in the composite material,a phenomenon that correlates with an increasing metallic ratio.The batch adsorption model was used to conduct the adsorption studies under various conditions of contact time,adsorbent quantity,and solution p H.Adsorption is governed by pseudo-second-order kinetics and the Langmuir model.Maximum monolayer adsorption capacities for CR and MB were calculated to be 344 and 200 mg/g,respectively.As the quantity of dosage increased from the 0.01-0.04 g,the percent removal efficiency(%)increased from75-87%for S2-LDH,84-88%for S2-MMT,86-93%for S3-MMT,and 95-97%for S4-MMT for CR dye and 82-85%for S2-LDH,83-89%for S2-MMT,83-91%for S3-MMT,and 84-92%for S4-MMT for MB dye.The removal percentage of CR dye for adsorbents S2-LDH,S2-MMT,S3-MMT,and S4-MMT were 75%,84%,86%,and 95%,respectively and 82%,83%,83%,and 85%,respectively for the removal of MB dye.The presence of MMT significantly increases the affinity of Ni/Mg/Al-LDHs(NMA-LDHs),and the designed production technique can be used to produce a variety of compositionally distinct adsorbent materials.(3)Layered double hydroxides are being researched as potential photocatalysts for degrading organic contaminants due to their large surface area,strong anionic exchange capacity,and adjustable composition.In this study,we modified Mg/Al-LDHs with Ni and Cr to improve their ability to remove MO,an anionic dye commonly used in textiles,cosmetics,and healthcare products.The modified Mg/Al-LDHs were synthesized using hydrothermal co-precipitation method and characterized by XRD,SEM,FTIR and transmission electron microscope(TEM).The breakdown rate of MO under solar light was used for evaluating the material’s photocatalytic activity.The outcomes demonstrated that the Ni/Mg/Al/Cr(LDH-4)photocatalyst degraded MO more quickly than the undoped substance.The addition of Cr to the Ni/Mg/Al matrix caused the band gap to develop new energy levels,which increased the material’s photocatalytic activity.In summary,Ni/Mg/Al doped with Cr has demonstrated tremendous potential as a photocatalyst for the MO degradation.The material is a good option for usage in a variety of industrial applications due to its high efficiency and stability. |
