Green synthesis of nickel nanoparticles using Ocimum sanctum and their application in dye and pollutant adsorption

Nickel nanoparticles as an eco-friendly adsorbent was biosynthesized using Ocimum sanctum leaf extract. The phys-iochemical properties of green synthesized nickel nanoparticles (NiGs) were characterized by UV–Vis spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). NiGs were used as adsorbent for the removal of dyes such as crystal violet (CV), eosin Y (EY), orange I (OR) and anionic pol utant nitrate (NO3?), sulfate (SO42?) from aqueous solution. Adsorption capacity of NiGs was examined in batch modes at different pH, contact time, NiG dosage, initial dye and pol utant concentration. The adsorption process was pH dependent and the adsorption capacity increased with increase in contact time and with that of NiG dosage, whereas the adsorption capacity decreased at higher con-centrations of dyes and pol utants. Maximum percentage removal of dyes and pol utants were observed at 40, 20, 30, 10 and 10 mg·L?1 initial concentration of CV, EY, OR, NO3?and SO42?respectively. The maximum adsorption capacities in Langmuir isotherm were found to be 0.454, 0.615, 0.273, 0.795 and 0.645 mg·g?1 at pH 8, 3, 3, 7 and 7 for CV, EY, OR, NO3?and SO42?respectively. The higher coefficients of correlation in Langmuir isotherm sug-gested monolayer adsorption. The mean energies (E), 2.23, 3.53, 2.50, 5.00 and 3.16 kJ·mol?1 for CV, EY, OR, NO3?and SO42?respectively, calculated from the Dubinin–Radushkevich isotherm showed physical adsorption of adsor-bate onto NiGs. Adsorption kinetics data was better fitted to pseudo-second-order kinetics with R2 N 0.870 for al dyes and pol utants. NiGs were found to be an effective adsorbent for the removal of dyes and pol utants from aque-ous solution and can be applied to treat textile and tannery effluents.     

污泥含炭吸附剂的制备及其吸附模拟烟气中汞蒸汽的应用(英文)

The carbonaceous adsorbent was prepared from mixtures of dewatered sludge and sawdust with enhanced ZnCl2 chemical activation.Characteristics of the adsorbent were studied using scanning electron microscope(SEM) ,Fourier transform infrared spectroscopy(FT-IR) ,and adsorption of nitrogen.The surface analysis showed that the carbonaceous adsorbent had good specific surface and porosity(394 m 2 ·g-1of BET surface,0.12 and 0.10 ml·g-1of microporous and mesoporous volume,respectively) .The oxygen functional groups such as OH,C O and C O were found on the surface by FTIR and XPS(X-ray photoelectron spectroscopy) .The adsorption of elemental mercury(Hg0) on the carbonaceous adsorbent was studied in a fixed bed reactor.The dynamic adsorption capacity of carbonaceous adsorbent increased with influent mercury concentration,from 23.6μg·g-1at 12.58μg·m-3to 87.9μg·g-1at 72.50μg·m-3,and decreased as the adsorption temperature increased,from 246 μg·g-1 at 25°C to 61.3μg·g-1 at 140°C,when dry nitrogen was used as the carrier gas.The carbonaceous adsorbent presented higher dynamic adsorption capacity than activated carbon,which was 81.2μg·g-1and 53.8μg·g-1respectively.The adsorption data were fitted to the Langmuir adsorption model.The physical and chemical adsorption were identified on the adsorbent.     

Synthesis of activated carbons from black sapote seeds,characterization and application in the elimination of heavy metals and textile dyes

Many different techniques may be used to remove industrial pollutants from wastewater. Adsorption using activated carbon has been reported to be an effective method. This work proposes the use of a vegetable residue (black sapote seeds) as a raw material for its synthesis. These carbons were chemically activated using phosphoric acid and carbonized at 673 and 873 K. Adsorption isotherms were constructed for the textile dyes on the carbons, and this data was treated using Langmuir's equation to quantitatively describe the adsorption process. The synthesized carbons were characterized using FTIR, EA, SEM, Nitrogen adsorption (specific surface areas of 879 and 652 m²·g^-1), and their points of zero charge (2.1 and 2.3). It was possible to adsorb both heavy metals and textile dyes present in aqueous solutions and wastewaters using these activated carbons. Heavy metals were adsorbed almost completely by both carbons. Cationic dyes where adsorbed (58-59.8 mg·g^-1) in greater amounts compared to anionic dyes (10-58.8 mg·g^-1). The amount of anionic dyes adsorbed increased almost 30% by changing the pH of the solutions. One of the carbons was thermally regenerated on three occasions without losing its adsorption capacity and it was proved in a flow system.     

Superior adsorption performance of graphitic carbon nitride nanosheets for both cationic and anionic heavy metals from wastewater

Water pollution caused by highly toxic Cd(II), Pb(II), and Cr(VI) is a serious problem. In the present work,a green and low-cost adsorbent of g-C_3N_4 nanosheets was developed with superior capacity for both cationic and anionic heavy metals. The adsorbent was easily fabricated through one-step calcination of guanidine hydrochloride with thickness less than 1.6 nm and specific surface area of 111.2 m~2·g~(-1). Kinetic and isotherm studies suggest that the adsorption is an endothermic chemisorption process, occurring on the energetically heterogeneous surface based on a hybrid mechanism of multilayer and monolayer adsorption. The tri-s-triazine units and surface N-containing groups of g-C_3N_4 nanosheets are proposed to be responsible for the adsorption process.Further study on pH demonstrates that electrostatic interaction plays an important role. The maximum adsorption capacity of Cd(II), Pb(II), and Cr(VI) on g-C_3N_4 nanosheets is 123.205 mg·g~(-1), 136.571 mg·g~(-1),and 684.451 mg·g~(-1), respectively. The better adsorption performance of the adsorbent than that of the recently reported nanomaterials and low-cost adsorbents proves its great application potential in the removal of heavy metal contaminants from wastewater. The present paper developed a promising adsorbent which will certainly find applications in wastewater treatment and also provides guiding significance in designing adsorption processes.     

合成的沸石活性污泥改进铵离子吸附和沉降性能(英文)

Municipal wastewater treatment plants typically exhibit two classic problems： high ammonium concen- tration in water after conventional biological treatment and, in some cases, poor activated sludge sediment ability. Potential solutions to these problems were investigated by adding a synthetic zeolite obtained from coal fly ash to different steps of activated sludge treatment. The experimental results for ammonium removal fit well with the theoretical adsorption isotherms of the Freundlich model with a maximum adsorption capacity of 13.72 mg.g-＇. Utiliza- tion of this kind of zeolite to improve activated sludge sediment ability is studied for the first time in this work. It is found that the addition of the zeolite （1 g. L-1） to an activated sludge with settling problems significantly enhances its sediment ability and comoact ability. This is confirmed by the sludge volume index （SVI）, which was reduced from 163 ml.g-1 to 70 ml.g-r, the V60 value, which was reduced from 894 ml.L-1 to 427 ml.L-1, and the zeta poten- tial （0, which was reduced from -19.81 mV to -14.29 mV. The results indicate that the addition of this synthetic zeolite to activated sludge, as an additional waste management practice, has a positive impact on both ammonium removal and sludge settleability.     

阳离子淀粉染料吸附材料的制备及表征

以玉米淀粉为原料,以3-氯-2-羟丙基三甲基氯化铵（CHPTMAC）为阳离子醚化剂,以NaOH为催化剂,制备了天然高分子多糖基染料吸附剂阳离子淀粉（CS）,用于对活性染料的吸附。对醚化反应机理进行了系统研究,并考察了反应条件对CS取代度（DS）及反应效率（RE）的影响。采用RAM、XRD、SEM对产物进行表征。吸附实验表明,当DS为0.12,染料溶液pH为8时,CS对活性红195、活性金黄K-2RA的吸附量分别为21.0和20.4 mg·g^-1,去除率可达84.1%和81.6%,好于无机吸附材料活性炭。还进行了CS染料吸附材料的再生实验,4次再生后仍有较高的吸附量,表明CS染料吸附材料具有较强的可再生性能,可循环使用。该天然基染料吸附剂CS有望成为无机吸附剂及合成树脂吸附剂的理想替代品,用于工业染料废水的处理中。     

Production of carbonaceous material from avocado peel for its application as alternative adsorbent for dyes removal

Adsorption processes have received special attention for contaminants removal thanks to their capability to generate effluents with high quality as well as their simple design. In the current work, the agro-waste residue avocado peel is proposed to be used as alternative to conventional activated carbons whose use is sometimes restricted to high costs, upgraded by their exhausting after long term operations. The carbonization procedure was optimized and analyzed through factorial design and response surface methodology by evaluating temperature(400–900 °C) and time(30–90 min) effects: optimal conditions were found at 900 °C and 65 min, generating an adsorbent with 87.52 m2·g-1of BET surface area, a mesopore volume of 74% and a zero point charge at 8.6. The feasibility of the carbonaceous material was proved for the removal of a variety of dyes by investigating substrate(10–50 mg·L-1) and solid(0.5–20 g·L-1) concentration effects and statistical significance: complete removal of Naphthol Blue Black and Reactive Black 5 was reached under optimal conditions(10 mg·L-1and20 g·L-1of dye and solid, respectively), while Basic Blue 41 was eliminated by using 13.4 g·L-1of the adsorbent.Overall, dyes removal by adsorption on carbonized avocado peel is presented as a promising technology due to the low cost and easy availability of the precursor, as well as the straightforward generation, the satisfactory characteristics and the proved adsorption capacity of the adsorbent.     

Superb VOCs capture engineering carbon adsorbent derived from shaddock peel owning uncompromising thermal-stability and adsorption property

High applied thermal-stability and superior structural property for activated carbon adsorbent are extremely promising, which also is the determining short slab in volatile organic compounds (VOCs) adsorption applications. Herein, we develop the outstanding engineering carbon adsorbents from waste shaddock peel which affords greatly-enhanced thermal-stability and super structural property (S_Lang?=?4962.6?m²·g^-1, V_micro?=?1.67?cm³·g^-1). Such character endows the obtained adsorbent with ultrahigh adsorption capture performance of VOCs specific to benzene (16.58?mmol·g^-1) and toluene (15.50?mmol·g^-1), far beyond traditional zeolite and activated carbon even MOFs materials. The structural expression characters were accurately correlated with excellent adsorption efficiency of VOCs by studying synthetic factor-controlling comparative samples. Ulteriorly, adsorption selectivity prediction at different relative humidity was demonstrated through DIH (difference of the isosteric heats), exceedingly highlighting great superiority (nearly sixfold) in selective adsorption of toluene compared to volatile benzene. Our findings provide the possibility for practical industrial application and fabrication of waste biomass-derived outstanding biochar adsorbent in the environmental treatment of threatening VOCs pollutants.     

Synthesis of an ordered mesoporous carbon with graphitic characteristics and its application for dye adsorption

An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater.     

Adsorption of urea,creatinine, and uric acid from three solution types using spherical activated carbon and its recyclability

In this paper, we propose that the urinary toxins from the wastewater be adsorbed on an adsorbent such as spherical activated carbon and the latter be regenerated by subjecting it to high temperatures to recycle activated carbon and also to recycle the water used in dialysis. We studied the adsorption of artificial waste dialysate, which is a mixed solution of urea, creatinine, and uric acid, and the separate solutions for each of these and found that their extents of adsorption onto the spherical activated carbon material were nearly identical. The amount of adsorption was approximately 1.4 mg·g^-1 for urea, 18 mg·g^-1 for creatinine, and 20 mg·g^-1 for uric acid. The urea, creatinine, and uric acid adsorbed onto the spherical activated carbon decomposed on heat treatment at 500℃, and the adsorption capacity of the spherical activated carbon was regenerated. Our study successfully demonstrated that the spherical activated carbon can be recycled in the waste dialysate treatment process.     

生物除磷颗粒污泥去除Pb2+的效能机制

以好氧颗粒污泥的吸附作用和磷酸盐对重金属的螯合作用为基础,采用富含磷酸盐的生物除磷颗粒污泥作为吸附剂来处理含铅废水,考察了不同吸附条件（pH、Pb²⁺的初始浓度、吸附反应时间）下,颗粒污泥对Pb²⁺的去除效果。结果表明,除磷颗粒污泥在pH为4,初始Pb²⁺浓度为150 mg·L^-1时,对铅的去除率最高（为99.9%）;在吸附反应20 min时即可达到吸附平衡。生物除磷颗粒污泥对Pb²⁺的吸附可以用Langmuir模型拟合（R²=0.993）,最大吸附量为49.5 mg·g^-1。其中离子交换和磷酸盐与Pb²⁺的螯合作用对除磷颗粒污泥去除Pb²⁺起到重要作用;傅里叶变换红外光谱（FTIR）测定表明-COOH、-OH、磷酰基等多种官能团也参与了除磷颗粒污泥除Pb²⁺过程。     

COS吸附剂的性能评价

以γ-Al_2O_3为主要组成,添加质量分数2%~5%的Cu O、2%~5%的Zn O和1%~2%Mo O_3,采用盘式造粒成型工艺制备(2~3)mm的球形颗粒,通过烘干和焙烧制备出比表面积(200~250)m~2·g~(-1)的载体,然后用碱金属氢氧化物对载体进行修饰,制得COS吸附剂,并考察其对COS的吸附性能。结果表明,通过添加活性氧化物的产品对COS的吸附性能良好,对COS吸附容量达11.5 mg·g~(-1),可将COS脱除至0.02 mg·m~(-3)。     

Conversion of Malaysian low-rank coal to mesoporous activated carbon: Structure characterization and adsorption properties

Malaysian Selantik low-rank coal (SC) was used as a precursor to prepare a form of mesoporous activated carbon (SC-AC) with greater surface area (SA) via a microwave induced KOH-activation method. The characteristics of the SC and SC-AC were evaluated by the iodine number, ash content, bulk density, and moisture content. The structure and surface characterization was carried out using pore structure analysis (BET), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), elemental analysis (CHNS), thermogravimetric analysis (TGA), and determination of the point of zero charge (pH_PZC). These results signify a mesoporous structure of SC-AC with an increase of ca. 1160 times (BET SA=1094.3 m²·g^-1) as compared with raw SC without activation (BET SA=1.23 m²·g^-1). The adsorptive properties of the SC-AC with methylene blue (MB) was carried out at variable adsorbent dose (0.2-1.6 g·L^-1), solution pH (2-12), initial MB concentrations (25-400 mg·L^-1), and contact time (0-290 min) using batch mode operation. The kinetic profiles follow pseudo-second order kinetics and the equilibrium uptake of MB conforms to the Langmuir model with a maximum monolayer adsorption capacity of 491.7 mg·g^-1 at 303 K. Thermodynamic functions revealed a spontaneous endothermic adsorption process. The mechanism of adsorption included mainly electrostatic attractions, hydrogen bonding interaction, and π-π stacking interaction. This work shows that Malaysian Selantik low-rank coal is a promising precursor for the production of low-cost and efficient mesoporous activated carbon with substantive surface area.     

聚酰胺接枝纤维素的合成及对金属离子的吸附性能

以葡萄秸秆为原料提取纤维素,以环氧树脂为交联剂,将聚酰胺交联到纤维素上制得聚酰胺-葡萄纤维素吸附剂。测定聚酰胺-葡萄纤维素吸附剂对Co2+和Fe2+的吸附性能,并研究环氧树脂用量、反应温度和吸附平衡时间对吸附性能的影响。结果表明,当反应温度25℃、吸附平衡时间60 min和m(聚酰胺)∶m(葡萄纤维素)∶m(环氧树脂)=2∶1∶1.5时,制备的聚酰胺-葡萄纤维素吸附剂的吸附性能最好。聚酰胺-葡萄纤维素吸附剂对Co2+和Fe2+的吸附均在60 min后达到平衡,Fe2+和Co2+的最大吸附容量分别为22.40 mg·g-1和16.82 mg·g-1。     

Protein-derived nitrogen and sulfur co-doped carbon for efficient adsorptive removal of heavy metals

A nitrogen and sulfur co-doped carbon has been synthesized employing egg white as a sustainable protein-rich precursor. According to CHNS elemental analysis, N, S and O heteroatoms accounted for mass fractions of 3.66%, 2.28% and 19.29% respectively, and the types of surface functionalities were further characterized by FT-IR and XPS measurements. Although the carbon possessed a smaller surface area (815 m²·g^-1) compared to a commercial activated carbon (1100 m²·g^-1), its adsorption capacity towards Co²⁺ reached 320.3 mg·g^-1, which was over 8 times higher compared to the limited 34.0 mg·g^-1 over the activate carbon. Furthermore, the carbon was found to be an efficient adsorbent towards a series of metal ions including VO²⁺, Cr³⁺, Ni²⁺, Cu²⁺ and Cd²⁺. Combined with its environmental merits, the protein derived carbon may be a promising candidate for heavy metal pollution control.     

Mesoporous activated carbon-zeolite composite prepared from waste macadamia nut shell and synthetic faujasite

Novel activated carbon-zeolite composite adsorbent was prepared from macadamia shell bio-waste and synthetic zeolite X using hydrothermal treatment.Characterisation studies revealed mainly mesoporous structure with 418 m~2·g~(-1) BET surface area with faujasite clusters on the carbon carrier.Sorption capacity for methylene blue model pollutant increased from 85 to 97 mg·g~(-1) with the temperature increase from 25 to 45 ℃, and improved with increasing pH.Nonlinear regression analyses found accurate fit to the pseudo-first-order kinetics model and intra-particle diffusion rate controlling mechanism.Excellent fits to the Jovanovic isotherm model indicated monolayer coverage on chiefly homotattic surfaces with variable potential.The thermodynamic analysis confirmed spontaneous and endothermic physisorption process.The spent adsorbent was regenerated with 20% capacity loss over five reuse cycles.Although the adsorbent was developed for ammonia, heavy metal and organic matter removal from water sources, the results also indicate good performance in cationic dye removal from wastewaters.     

Static and dynamic adsorption of fluoride using La(Ⅲ)-loaded chitosan beads crosslinked with EGDE

利用乙二醇二缩水甘油醚(EGDE)替代戊二醛对壳聚糖微球进行交联,然后负载稀土镧离子La(Ⅲ),制备得到新型的除氟剂（CEB-La）。研究了CEB-La对F^-的静态和动态吸附性能。静态吸附实验结果表明：该除氟剂的静态吸附条件为pH7.0、温度50℃、吸附时间60 min、振荡频率120 r·min^-1;当CEB-La用量3 g·L^-1时,对浓度10 mg·L^-1含氟水的除氟率可达92.9%;CEB-La对F^-的吸附过程符合Langmuir和Freundlich吸附等温线,饱和吸附容量为25.7 mg·g^-1;拟二级动力学方程能较好地描述CEB-La对F^-的吸附动力学过程;CEB-La吸附饱和后,经NaOH溶液处理后再与镧离子螯合,可有效再生;共存阴离子特别是CO ^{2 -}₃ 和HCO^-₃对CEB-La的除氟性能有不利影响。动态吸附实验结果表明：进水流量3 ml·min^-1时,CEB-La适于处理F^-浓度2～15 mg·L^-1的含氟水;利用Thomas模型可较好地描述CEB-La对F^-的动态吸附特征,动态饱和吸附容量为3.67 mg·g^-1。因此,CEB-La的除氟性能优越,再生方法简单,使用成本较低,具有较好的应用前景。     

Synthesis of a novel functional group-bridged magnetized bentonite adsorbent:Characterization,kinetics, isotherm,thermodynamics and regeneration

A novel magnetic adsorbent was synthesized by magnetizing bentonite by APTES-Fe_3O_4 via a functional groupbridged interaction. The characterization of APTES-Fe_3O_4/bentonite was conducted via transmission electron microscope(TEM), X-ray diffraction(XRD), Fourier transform infrared spectrophotometer(FT-IR), thermal gravimetric analysis(TGA), vibrating sample magnetometer(VSM), zeta potential analysis and Brunner–Emmet–Teller(BET). The APTES-Fe_3O_4/bentonite was assessed as adsorbents for methylene blue(MB) with a high adsorption capacity(91.83 mg·g~(-1)). Factors affecting the adsorption of MB(such as p H, equilibrium time, temperature and initial concentration) were investigated. The adsorption process completely reaches equilibrium after 120 min and the maximum sorption is achieved at p H 8.0. The adsorption trend follows the pseudosecond order kinetics model. The adsorption data gives good fits with Langmuir isotherm model. The parameter factor RLfalls between 0 and 1, indicating the adsorption of MB is favorable. The adsorption process is endothermic with positive ΔH~0 values. The positive values of ΔG~0 confirm the affinity of the adsorbent towards MB, and suggest an increased randomness at the solid–liquid interface during the adsorption process. Regeneration of the saturated adsorbent was easily carried out via gamma-irradiation.     

干法制备高中孔率生物质成型活性炭

以锯末为原料,氯化锌为活化剂,不添加黏结剂,采用干法混合后直接成型活化制备高中孔率生物质成型活性炭。为考察这种工艺的可行性,通过单因素实验,以亚甲基蓝吸附值为评价指标,考察了盐料比、活化温度、活化时间与成型密度对生物质成型活性炭吸附性能的影响,得出较优工艺条件为:盐料比1.0:1,活化温度950℃,活化时间为60min,成型密度为1.4g·cm^-3。在此工艺条件下制备得到的生物质成型活性炭,其亚甲基蓝吸附值为387mg·g^-1,BET比表面积为2104m²·g^-1,平均孔径为3.11nm,总孔容为1.63cm³·g^-1,中孔孔容为1.17cm³·g^-1,中孔率高达71.8%,初步证明了干法制备高中孔率生物质成型活性炭工艺的可行性。     

Kinetic and thermodynamic studies of acid scarlet 3R adsorption onto low-cost adsorbent developed from sludge and straw简

A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 ma. g-l, micropore volume of 0.176 cm2·g-1 and average pore radius of 5.0 nm. The kinetic, equilibrium isotherm and thermodynamic characteristics of trisodium 1-（1-naphthylazo）-2-hydroxynaphthalene- 4＇,6,8-trisulphonate （acid scarlet 3R） onto the adsorbent from sludge and straw were investigated. The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R. Thus, the adsorption phenomenon was suggested as a chemical process. The adsorption data were fitted better with Langmuir model than Freundlich model, indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.