Photocatalytic degradation of alizarin red dye in aqueous medium using carbon nanotubes/Cu–Ti oxide composites

ABSTRACT

Multiwalled carbon nanotubes/copper and titanium oxides (MWNTs/Cu–Ti) and Cu–Ti composites were synthesized by wet chemical precipitation method and were used as photocatalysts for photodegradation of alizarin red dye in aqueous media. The morphological study presented that MWNTs are well covered by Cu–Ti. The formation of Cu–Ti was confirmed by energy dispersive X-rays (EDX) and X-rays diffraction (XRD). The MWNTs/Cu–Ti degraded about 92.51% within 180 min. The effect of other parameters like pH, catalyst dosage, and concentration of dye on the photocatalytic degradation was also studied. The activity of recovered and re-recovered catalysts was also studied.     

TiO2粉体光催化降解四种可溶性染料的研究

采用溶胶-凝胶法制备TiO2粉体,光催化降解了亚甲基蓝、孔雀石绿、酸性品红、甲基橙等四种染料.研究了染料浓度、pH值、催化剂用量、时间等因素对四种染料光催化降解的影响.在染料的浓度为5 mg·L-1(甲基橙10 mg·L-1)、pH=7、TiO2粉体的用量为2 g·L-1、光照时间为1.0 h,其脱色率可以达到90%以上.     

Spectrophotometric studies of photo-induced degradation of Tertrodirect Light Blue (TLB) using a nanostructure zinc zirconate composite

Zinc zirconate nanopowder (ZZN) photocatalyst was prepared by sol–gel method using zinc acetate and zirconium acetylacetonate as precursors. The optimal calcination temperature was 800 °C and ZnZrO₃ phase was formed. The structural and morphology properties of the nanocomposite were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDAX) and ultraviolet visible diffuse reflectance (UV-DRS). The SEM observation for ZZN showed the average grain size of 26 nm. UV–vis diffuse reflectance spectra (DRS) of the nanocomposite showed an absorption edge at 355 nm. The catalytic activity of ZZN was investigated by degradation of Tertrodirect Light Blue (TLB) dye in water using UV–vis spectroscopy (UV–vis) with an initial concentration of 20 mg/L dye. The influence of the catalyst concentration, time of irradiation and pH on photodegradation of dye was investigated. The results showed that degradation of TLB dye can be conducted in the photocatalytic process. Accordingly, a degradation of more than 97% of dye was achieved by applying the optimal operational parameters with 30 mg/L of catalyst, pH 9 at 1 h irradiation.     

LaCoO_3光催化降解孔雀绿染料的研究

采用硬脂酸溶胶-凝胶法合成出钙钛矿型复合氧化物LaCoO3,用XRD,TEM等手段进行了表征,并以其为催化剂对染料孔雀绿进行降解实验。以高压汞灯为光源,研究了催化时间、催化剂用量、染料起始浓度、溶液pH值以及H2O2加入量对降解率的影响。结果表明,100 mL10 mg/L孔雀绿溶液用0.15 g催化剂降解2 h,降解率达到90.1%,加入适量的H2O2、提高溶液pH值均会提高染料的降解率。     

Synthesis and characterization of interpenetrating polymer network based on sodium alginate and methacrylic acid and potential application for immobilization of TiO2 nanoparticles

An interpenetrating polymer network (IPN) based on the sodium alginate (A) and partially neutralized poly(methacrylic acid) (MAA) was prepared by free radical polymerization followed by additional cross‐linking of sodium alginate with calcium ions. Obtained material (A/MAA IPN) was characterized by FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and rheological measurements. Swelling behavior of synthetized IPN has been also investigated. TiO₂ nanoparticles (TiO₂ NPs) were immobilized onto A/MAA IPN by dip‐coating method and obtained TiO₂/IPN nanocomposite was used for removal of the methylene blue (MB) from aqueous solution. The photodegradation (under illumination) and sorption (in the dark) processes for dye removal were monitored through decrease of dye concentration in the solution by UV/VIS spectrometer. The TiO₂/IPN nanocomposite sorbed approximately 93% of the MB from a 10 mg L^?1 MB solution in the dark, but no degradation occurred. Likewise, more than 93% of dye was removed after 8 h of illumination. However, after 24 h of illumination, the samples were discolored indicating that dye molecules were successfully degraded. Thus, the TiO₂/IPN nanocomposite could be utilized in the photodegradation–sorption process for the abatement of pollutants in water. POLYM. ENG. SCI., 55:2511–2518, 2015. © 2015 Society of Plastics Engineers     

Fe3+/TiO2光催化剂降解孔雀绿染料的研究

采用快速溶胶法制备纳米TiO2光催化剂,用Fe^3 对其掺杂改性,并进行了催化剂的X-射线衍射分析(XPd3),傅立叶红外光谱分析(FT-IR),BET比表面积的表征,用于光催化降解水中孔雀绿染料的研究．研究了不同催化剂的光催化活性,确定了光催化剂的用量．结果发现60W紫外光辐射80min,孔雀绿可以彻底降解;可见光下,光催化剂对孔雀绿降解120h,其转化率为98%,COD的去除率为75．3%。可见光下孔雀绿的脱色率和COD的变化不一致,并对其产生的原因和孔雀绿的光催化降解机理作了探讨。孔雀绿的光催化降解符合一级动力学反应规律,反应速率常数随催化剂的用量增加而增大,但增大幅度逐渐减小。     

La掺杂ZnO的制备及其光催化降解孔雀石绿

采用溶胶?凝胶法制备了不同La掺杂量的La/ZnO催化剂,分析了其组成和性质,以孔雀石绿溶液为染料模型,研究了催化剂的光催化降解性能. 结果表明,ZnO为六角纤锌矿结构,La3+以小La2O3簇的形式均匀分布在ZnO纳米颗粒上. 摩尔比La:Zn=0.05时La/ZnO具有良好的催化活性,用300 W汞灯照射2 h,孔雀石绿的降解率可达98.8%,300 W氙灯照射2 h降解率达90.4%,比ZnO的降解率提高了51.2%.     

α-SiW_（11）Ti/聚苯胺/TiO_2复合材料的光催化性能

以α-SiW11Ti/PANI/TiO2为光催化剂。在紫外灯辐射下,研究了模拟染料废水孔雀石绿溶液的光催化降解的反应,考察了催化剂投加量、底物浓度、pH值对孔雀石绿降解率的影响。结果表明,孔雀石绿溶液光催化降解的最佳条件为：pH=11,α-SiW11Ti/PANI/TiO2催化剂投加量为0.125 g.L-1,浓度为10 mg.L-1,经30 W紫外灯照射90 min后,其降解率为97.53%。     

石墨烯-Bi2MoO6可见光催化降解4BS染料

采用溶剂热合成法制备性能稳定的可见光石墨烯-Bi₂MoO₆复合催化剂,研究催化剂对4BS染料的光催化降解效果以及4BS溶液浓度pH、催化剂用量和石墨烯-Bi₂MoO₆复合催化剂重复使用次数等对光催化降解效果的影响。结果表明,在催化剂用量0.50 g·L^－1、染料初始浓度20 mg·L^－1和碱性条件下,光照反应150 min后,4BS去除率达98.5%,催化剂重复使用5次,4BS去除率达78%。复合催化剂结构稳定,可见光下能够有效降解4BS染料。     

Photocatalytic degradation of Direct Yellow 12 dye using UV/TiO2 in a shallow pond slurry reactor

The adsorption and photocatalytic degradation of diazo Direct Yellow 12 (Chrysophenine G), commonly used as a cotton, paper and leather dye has been investigated in aqueous suspension of semiconductor oxide TiO₂ as photocatalyst in a non-concentrating shallow pond slurry type reactor under UV light. The adsorption of dye on the semiconductor shows a strong dependence on the pH and follows a Langmuir adsorption model. The studies include dark adsorption experiments at different pH conditions and their effect on initial rate of photodegradation. The effect of initial concentration of dye, catalyst loading, pH, addition of oxidant on the reaction rate was ascertained and optimum conditions for maximum degradation was determined. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir–Hinshelwood model. COD analysis of the dye under optimum conditions showed 94% reduction in COD after 2.5 h and complete decolourisation as determined by UV–vis analysis was achieved in 1.5 h.     

Photocatalytic degradation of organic pollutants by simple cerium(III) salt

A simple cerium salt Ce(NO₃)₃ was used as the catalyst for alizarin green (AG) degradation under UV irradiation. It was found that the anthraquinone dye can be completely removed by the system. The photodegradation reaction mainly involved the participation of hydroxyl radical, which was generated by the oxidation of Ce(III) ions to Ce(IV); while the Ce(IV) ion itself could only decolorize the dye with a relatively slow rate. Several intermediate products were detected by electrospray ionization mass spectrometry and a possible pathway was proposed. Many other organic dyes and phenol could also be efficiently degraded by the system.     

Microwave-assisted synthesis of biodegradable interpenetrating polymer network of aloe vera–poly(acrylic acid-<Emphasis Type="Italic">co</Emphasis>-acrylamide) for removal of malachite green dye: equilibrium,kinetics and thermodynamic studies

The present work deals with the synthesis of a biodegradable interpenetrating polymer network (IPN) consisting of natural polysaccharide aloe vera, acrylamide and acrylic acid. Biodegradability of the synthesized IPN was studied through soil burial and composting methods. The synthesized IPN was completely degraded within 70 days through the composting method and showed 91% degradation within 77 days through the soil burial method. Evidence of biodegradation of the synthesized IPN was studied by different techniques, for instance Fourier infrared spectroscopy and scanning electron microscopy. The synthesized IPN was used as a device for the removal of malachite green dye. The effect of different reaction parameters on IPN synthesis and dye removal was investigated. The maximum dye adsorption occurred at pH 4.5, because at this pH methylene green dye molecules are present in monomeric state. The result of Weber–Morris intra-particle diffusion showed that the rate-limiting step was not the intra-particle diffusion. The adsorption isotherm models, i.e., Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Redlich–Peterson and Sips, were studied and it was found that the Langmuir was the best-fitting model for the experimental data. An increase in temperature resulted in a decrease in malachite green dye removal, suggesting that the adsorption process was exothermic in nature. This synthesis is important from industrial viewpoints.     

海泡石负载Bi_2O_3对孔雀石绿光催化降解性能研究

以海泡石为载体,采用化学沉淀法制备了负载型Bi_2O_3光催化剂。通过XRD、SEM、TEM、UV-vis对光催化剂进行了表征。以孔雀石绿为模型降解物考察了光催化剂的光催化活性,重点研究了光催化剂投加量、孔雀石绿溶液初始pH及溶液初始浓度对降解效果的影响。结果表明:当光催化剂投加量为1.0 g/L,孔雀石绿溶液初始pH为7,溶液初始质量浓度为50 mg/L,光照30 min,孔雀石绿的降解率达到95.7%,孔雀石绿溶液初始浓度越高,越不容易被降解,但光照60 min,所有浓度的孔雀石绿基本降解完毕,通过重复实验发现,该负载型Bi2O3的稳定性较高。     

Green synthesis of Ni@Fe3O4 and CuO nanoparticles using Euphorbia maculata extract as photocatalysts for the degradation of organic pollutants under UV-irradiation

This paper presents a fast, biogenic and green method for the synthesis of highly stable and small sized metal nanoparticles (MNPs). This technique has some benefits compared to the conventional physical and chemical methods. It is simple, rapid, cheap and environmentally friendly. In addition, it does not require any costly or hazardous chemicals. The extracts of Euphorbia maculata aerial parts were used in a green synthesis method in order to prepare magnetic Ni@Fe₃O₄ and CuO NPs. Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet–visible (UV–Vis), energy dispersive X-ray spectrometry (EDS), Brunauer-Emmett-Teller (BET) and thermo gravimetric-differential thermal analysis (TGA) analytical techniques were used for analyzing the green synthesized compounds. The photocatalytic activity of the synthesized NPs was tested in the degradation of different organic dye pollutants such as congo red (CR), methylene blue (MB) and Rhodamine B (RhB) under UV irradiation. The effects of different parameters such as nanoparticle dosage, contact time, pH, and initial dye concentrations on the capacity of the photocatalyst adsorption were also studied. The comparison of the photocatalytic activity of the biosynthesized nanoparticles reveals that the catalytic activity of CuO NPs is higher than that of Ni@Fe₃O₄ NPs. Furthermore, good photocatalytic stability of the NPs in the degradation of MB under UV light irradiation was observed after the recycling. The photocatalyst efficiency did not considerably change after four cycles, which indicated excellent photocatalytic stability.     

Synthesis of graphene-supported bimetallic nanoparticles for the sunlight photodegradation of Basic Green 5 dye in aqueous medium

Graphene nanosheets-supported Sn-Pt bimetallic nanoparticles (GNs/Sn-Pt) were prepared by precipitation method. The obtained GNs/Sn-Pt was used as a photocatalyst for photodegradation of Basic Green 5 (BG5) in aqueous solution under sunlight. The morphology and photodegradation study was performed by SEM and UV–VIS spectrophotometry, respectively. The SEM image showed the presence of Sn and Pt on GNs, being confirmed by energy dispersive X-ray (EDX) analysis. The photodegradation study of BG5 showed that the dye degradation increases as a function of irradiation time. The degradation of BG5 was found to be pH dependent and maximum degradation was found at higher pH.     

Mg掺杂TiO_2光催化降解孔雀绿染料的研究

采用溶胶-凝胶法制备的Mg掺杂TiO2光催化剂降解孔雀石绿(MG)染料废水,考察了MG初始浓度、催化剂加入量等因素对其降解的影响。结果表明,Mg的掺杂显著提高了TiO2光催化降解孔雀石绿的活性,当催化剂用量为1.0 g/L,经120 min紫外光照射后,可使30 mg/L孔雀石绿溶液降解率达到84%,同时讨论了光催化机制。     

Photocatalytic degradation of Rhodamine B dye using ZnO–SnO2 electrospun ceramic nanofibers

ZnO–SnO₂ nanofibers were fabricated by the electrospinning technique combined with calcination at 600 °C. Their structural and morphological properties were analyzed by X-ray diffraction and scanning/transmission electron microscopy, and their photocatalytic activity was investigated by the degradation of Rhodamine B (RhB) dye by visible light irradiation. UV–vis spectral data were used to estimate the photodegradation efficiency of the metal oxide nanocomposites. All the RhB dye samples were tested for six hours of degradation the highest efficiency being obtained for a molar ratio Sn/Zn of 0.030.     

磁性二氧化钛-磷钨酸复合催化剂的制备及光催化性能研究

采用层层自组装法成功制备了兼具磁性和光催化活性的双功能Fe_3O_4@SiO_2/(TiO_2/PW_(12))_(10)复合微球,利用扫描电镜、红外光谱和X-射线能谱仪对所得微球进行了结构和形貌的表征。以甲基橙为模型污染物,研究了紫外光下Fe_3O_4@SiO_2/(TiO_2/PW_(12))_(10)的光催化性质,系统考察了甲基橙溶液的初始浓度、溶液pH和无机氧化剂碘酸钾对复合膜催化效率的影响。动力学研究表明,在不同浓度甲基橙溶液中,染料的光催化降解遵循表观一级反应动力学。磁性Fe_3O_4纳米粒子的使用实现了反应后催化剂方便、快速和高效地分离回收。     

La-doped WO3@gCN Nanocomposite for Efficient degradation of cationic dyes

In present investigation, gCN supported carbon coated Lanthanum doped tungsten oxide (C@LWO/gCN) composite were synthesized via hydrothermal approach. The photodegradation of different cationic dyes like malachite green (MG), crystal violet (CV) and methylene blue (MB) has been carried out under prepared C@LWO/gCN composite. Furthermore, the comparative photodegradation was also performed using pristine LWO and C@LWO nanowires. The synthesized samples were characterized via physiochemical techniques such as XRD, FESEM, EDX, FTIR, BET and UV/Vis spectroscopy. The results proved incorporation of La ions into WO₃ lattice and reduced band gap of doped sample which significantly boost up the capability of the material towards photodegradation. The maximum degradation was found out at pH = 6, 5 mg catalyst dose, 5 ppm dye concentration and 35 °C temperature. The achieved results proved that the trapping agents compete with prepared composite specie for the h⁺, e⁻, HO^● and O₂^●- radicals. The obtained experimental records of photodegradation of cationic dyes using C@LWO/gCN composite has correlation with pseudo first order kinetics, Langmuir-Hinshelwood model and t_1/2. The simplest facile synthetic approach, remarkable photodegradation performance against colored and colorless effluents suggest that C@LWO/gCN composite exhibit great potential for large-scale wastewater treatment.     

Fe／Mn／Al2O3催化H2O2降解偶氮染料废水的研究

以活性氧化铝为载体,制备了Fe／Mn／Al2O3负载型催化剂,用于催化H2O2氧化降解偶氮染料活性黑5,探讨了pH、H2O2投加量、染料初始浓度、催化剂投加量等对染料脱色率的影响。结果表明,活性黑5的脱色率随催化剂投加量、H2O2投加量的增加而升高;而随活性黑5初始浓度的增加而降低。当H2O2投加量的增加达到200mg／L后,H2O2投加量的增加对活性黑5脱色效果的影响不显著。Fe／Mn／Al2O3／H2O2体系下,活性黑5在pH为2～9之间均有一定的脱色效果,活性黑5的脱色率随初始pH的增加而先增加后减少,其中在初始pH为3时脱色效果最佳。