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1.
The characteristics and mechanisms of hydrogen sulfide (H2S) adsorption on a biochar through pyrolysis at various temperatures (100 to 500°C) were investigated. The biochar used in the current study was derived from the camphor tree (Cinnamomum camphora). The samples were ground and sieved to produce particle sizes of 0.4 mm to 1.25 mm, 0.3 mm to 0.4 mm, and <0.3 mm. The H2S breakthrough capacity was measured using a laboratory-designed test. The surface properties of the biochar were characterized using pH and Fourier-transform infrared spectroscopy (FTIR) analysis. The results obtained demonstrate that all camphor-derived biochars were effective in H2S sorption. Certain threshold ranges of the pyrolysis temperature and surface pH were observed, which, when exceeded, have dramatic effects on the H2S adsorption capacity. The sorption capacity ranged from 1.2 mg/g to 121.4 mg/g. The biochar with 0.3 mm to 0.4 mm particle size possesses a maximum sorption capacity at 400°C. The pH and FTIR analysis results showed that carboxylic and hydroxide radical groups were responsible for H2S sorption. These observations will be helpful in designing biochar as engineered sorbents for the removal of H2S.

Implications: This paper studies the potential of biochar derived by camphor to adsorb hydrogen sulfide at environmentally sustainable temperatures. The different sizes of the biochars and the different temperatures of pyrolysis for the camphor particle have a great impact on adsorption of hydrogen sulfide.  相似文献   

2.
The characteristics and mechanisms of hydrogen sulfide (H2S) adsorption on three different biochars derived from agricultural/forestry wastes through pyrolysis at various temperatures (100 to 500 ºC) were investigated. In this study, the H2S breakthrough capacity was measured using a laboratory-characterized using pH and Fourier transform infrared spectroscopy analysis. The results obtained demonstrate that all biochars were effective in H2S sorption. The sorption capacity of the biochar for H2S removal is related to the pyrolysis temperature and pH of the surface. Certain threshold ranges of the pyrolysis temperature (from 100 to 500 ºC) and pH of the surface are presented. It also concluded that the sorption capacity (for removing H2S) of rice hull-derived biochar is the largest in three biochars (camphor-derived biochar, rice hull-derived biochar, and bamboo-derived biochar). These observations will be helpful in designing biochar as engineered sorbents for the removal of H2S.Implications: This paper focuses on the adsorption of hydrogen sulfide (H2S) by biochars derived from wastes. The characteristics and mechanisms of hydrogen sulfide (H2S) adsorption on three different boichars derived from agricultural/forestry wastes through pyrolysis at various temperatures were investigated. In this study, the H2S breakthrough capacity was measured using laboratory characterization with pH and Fourier-transform infrared spectroscopy analysis. The results obtained demonstrate that all biochars were effective in H2S sorption. The sorption capacity of the biochar for H2S removal is related to the pyrolysis temperature and pH of the surface.  相似文献   

3.
This paper explored biochar modification to enhance biochar’s ability to adsorb hexavalent chromium from aqueous solution. The ramie stem biomass was pyrolyzed and then treated by β-cyclodextrin/poly(L-glutamic acid) which contained plentiful functional groups. The pristine and modified biochar were characterized by FTIR, X-ray photoelectron spectroscopy, specific surface area, and zeta potential measurement. Results indicated that the β-cyclodextrin/poly(L-glutamic acid) was successfully bound to the biochar surface. Batch experiments were conducted to investigate the kinetics, isotherm, thermodynamics, and adsorption/desorption of Cr(VI). Adsorption capacities of CGA-biochar were significantly higher than that of the untreated biochar, and its maximum adsorption capacity could reach up to 197.21 mg/g at pH 2.0. Results also illustrated that sorption performance depended on initial solution pH; in addition, acidic condition was beneficial to the Cr(VI) uptake. Furthermore, the Cr(VI) uptake was significantly affected by the ion strength and cation species. This study demonstrated that CGA-biochar could be a potential adsorbent for Cr(VI) pollution control.  相似文献   

4.
Biochar is increasingly been used as a soil amendment to improve water-holding capacity, reduce nutrient leaching, increase soil pH, and also as a means to reduce contamination through sorption of heavy metals or organic pollutants. The sorption behavior of three phenylurea herbicides (monuron, diuron and linuron) on five biochars (Enhanced Biochar, Hog Waste, Turkey Litter, Walnut Shell and Wood Feedstock) and an agricultural soil (Yolo silt loam) was investigated using a batch equilibration method. Sorption isotherms of herbicides to biochars were well described by the Freundlich model (R2 = 0.93–0.97). The adsorption KF values ranged from 6.94 to 1306.95 mg kg?1 and indicated the sorption of herbicides in the biochars and Yolo soil was in the sequence of linuron > diuron > monuron and walnut shell biochar > wood feedstock biochar > turkey litter biochar > enhanced biochar > hog waste biochar > Yolo soil. These data show that sorption of herbicides to biochar can have both positive (reduced off-site transport) and negative (reduced herbicide efficacy) implications and specific biochar properties, such as H/C ratio and surface area, should be considered together with soil type, agriculture chemical and climate condition in biochar application to agricultural soil to optimize the system for both agricultural and environmental benefits.  相似文献   

5.
Abstract

Bentazone is one of the toxic insecticides used to control forest tent caterpillar moths, boll weevils, gypsy moths, and other types of moths in various field crops. We report the efficacy of biochar prepared from the Azardirachta Indica waste biomass as adsorbent for removal of Bentazone. Biochar material was prepared by pyrolysis process under limited oxygen conditions. Biochar material was characterized by proximate and ultimate analysis, SEM analysis, FTIR analysis and TG/DTA analyses. The Bentazone adsorption capacity by biochar from aqueous solutions was assessed. Effect of time, adsorbent dosage, insecticide concentration and pH on the adsorption characteristics of the biochar were evaluated. Adsorption parameters were obtained at equilibrium contact time of 150?min, with biochar dosage of 0.5?g at pH 8. From the optimization studies, desirability of 0.952 was obtained with response (adsorption uptake) of 79.40?mg/g, for initial concentration of insecticide (50?mg/L), adsorbent dosage (0.448?g), time 30.0?min and pH 2. The adsorption isotherm data for the removal of Bentazone fitted well with the Freundlich isotherm. This study indicates that the biochar produced from the bark of Azardirachta Indica biomass could be employed as a potential adsorbent for removal of synthetic organic pollutants from the water streams.  相似文献   

6.
This work reports kinetic and equilibrium studies of cadmium(II) and lead(II) adsorption by the brown seaweed Cystoseira baccata. Kinetic experiments demonstrated rapid metal uptake. Kinetic data were satisfactorily described by a pseudo-second order chemical sorption process. Temperature change from 15 to 45 degrees C showed small variation on kinetic parameters. Langmuir-Freundlich equation was selected to describe the metal isotherms and the proton binding in acid-base titrations. The maximum metal uptake values were around 0.9 mmol g(-1) (101 and 186 mg g(-1) for cadmium(II) and lead(II), respectively) at pH 4.5 (raw biomass), while the number of weak acid groups were 2.2 mmol g(-1) and their proton binding constant, K(H), 10(3.67) (protonated biomass). FTIR analysis confirmed the participation of carboxyl groups in metal uptake. The metal sorption was found to increase with the solution pH reaching a plateau above pH 4. Calcium and sodium nitrate salts in solution were found to affect considerably the metal biosorption.  相似文献   

7.

In this work, biochar (BC), activated carbon (AC), and graphene oxide (GO) were thiol-functionalized using 3-mercaptopropyltrimethoxysilane (3-MPTS) (named as BCS, ACS, and GOS, respectively). BCS, ACS, and GOS were synthesized mainly via the interaction between hydrolyzed 3-MPTS and surface oxygen-containing functional groups (e.g., –OH, O–C=O, and C=O) and π-π interaction. The materials before and after modification were characterized and tested for mercury removal, including sorption kinetics and isotherms, the effects of adsorbent dosage, initial pH, and ionic strength. Pseudo-second-order sorption kinetic model (R2 = 0.992~1.000) and Langmuir sorption isotherm model (R2 = 0.964~0.998) fitted well with the sorption data of mercury. GOS had the most –SH groups with the largest adsorption capacity for Hg2+ and CH3Hg+ (449.6 and 127.5 mg/g), followed by ACS (235.7 and 86.7 mg/g) and BCS (175.6 and 30.3 mg/g), which were much larger than GO (96.7 and 4.9 mg/g), AC (81.1 and 24.6 mg/g), and BC (95.6 and 9.4 mg/g). GOS and ACS showed stable mercury adsorption properties at a wide pH range (2~9) and ionic strength (0.01~0.1 mol/L). Mercury maybe removed by ligand exchange, surface complexation, and electrostatic attraction.

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8.
Aksu Z  Dönmez G 《Chemosphere》2003,50(8):1075-1083
Biosorption capacities and rates of different kinds of dried yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe, Kluyveromyces marxianus, Candida sp., C. tropicalis, C. lipolytica, C. utilis, C. quilliermendii and C. membranaefaciens) for Remazol Blue reactive dye from aqueous solutions were compared under laboratory conditions as a function of initial pH and initial dye concentration. Optimum initial biosorption pH was determined as 2 for all the yeasts. All the yeast species showed comparable and very high dye sorption at 100 mg/l initial dye concentration. The equilibrium sorption capacity of the biomass increased with increasing initial dye concentration up to 400 mg/l for Candida sp. C. lipolytica and C. tropicalis; up to 300 mg/l for C. quilliermendii and C. utilis and up to 200 mg/l for S. cerevisiae, S. pombe, K. marxianus and C. membranaefaciens while the adsorption yield of dye showed the opposite trend for all the yeasts. Among the nine yeast species, C. lipolytica exhibited the highest dye uptake capacity (Q(0) = 250 mg/g). Both the Freundlich and Langmuir adsorption models were found suitable for describing the biosorption of the dye by all the Candida yeasts (except C. membranaefaciens). The results indicated that the dye uptake process followed the pseudo-second-order kinetics for each dye-yeast system.  相似文献   

9.
The removal of heavy metals in urban runoff by sorption on mulch   总被引:3,自引:0,他引:3  
A series of adsorption experiments was conducted in order to assess the ability of three mulches to remove several of the heavy metal ions typically encountered in urban runoff. Three types of mulch, cypress bark (C), hardwood bark (H), and pine bark nugget (P), were selected as potential sorbents to capture heavy metals in urban runoff. The hardwood bark (H) mulch had the best physicochemical properties for adsorption of heavy metal ions. In addition, because of its fast removal rate and acceptably high capacity for all the heavy metal ions, it was concluded that the H mulch is the best of the three adsorbents for treatment of urban runoff containing trace amounts of heavy metals. In order to investigate the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The sorption of these metals on H mulch conformed to the linear form of the Langmuir adsorption equation. At pH 5 and 6, the Langmuir constants (S(m)) for each metal were found to be 0.324 and 0.359 mmol/g (Cu); 0.306 and 0.350 mmol/g (Pb); and 0.185 and 0.187 mmol/g (Zn) at 25 degrees C.  相似文献   

10.
改性膨润土对垃圾填埋场渗滤液吸附效果   总被引:2,自引:0,他引:2  
通过制备不同组分改性膨润土,研究其对苯酚的吸附效果,结果表明,十六烷基三甲基溴化铵+十二烷基磺酸钠+硫酸铝-改性膨润土>十六烷基三甲基溴化铵+十二烷基磺酸钠-改性膨润土>十六烷基三甲基溴化铵-改性膨润土。通过改性膨润土对实际复杂组分渗滤液的吸附研究,结果表明,使用活性炭改性的膨润土吸附COD和NH4+-N最为理想,单位质量COD吸附量最高为26.8 mg/g,NH4+-N最高为3.92 mg/g,其中,COD最高去除率为77.3%,氨氮为28.9%;十六烷基三甲基溴化铵+十二烷基磺酸钠+硫酸铝-改性膨润土对COD和NH4+-N均有去除效果,两者对于渗滤液实际处理工程具有应用价值。  相似文献   

11.
The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperature has great influence on the adsorption of H2S. At the different pyrolysis temperature, the H2S removal efficiency of rice hull-derived biochar was different. The adsorption capacities of biochar were 2.09 mg·g–1, 2.65 mg·g–1, 16.30 mg·g–1, 20.80 mg·g–1, and 382.70 mg·g–1, which their pyrolysis temperatures were 100 °C, 200 °C, 300 °C, 400 °C and 500 °C respectively. Based on the Yoon-Nelson model, it analyzed the mass transfer mechanism of hydrogen sulfide adsorption by biochar.

Implications: The paper focuses on the biochar derived from rice hull–removed hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperatures have great influence on the adsorption of H2S. At the different pyrolysis temperatures, the H2S removal efficiency of rice hull–derived biohar was different. The adsorption capacities of biochar were 2.09, 2.65, 16.30, 20.80, and 382.70 mg·g?1, and their pyrolysis temperatures were 100, 200, 300, 400, and 500 °C, respectively. Based on the Yoon-Nelson model, the mass transfer mechanism of hydrogen sulfide adsorption by biochar was analyzed.  相似文献   

12.
为了提高沸石对汞的吸附性,利用半胱胺盐酸盐对天然斜发沸石进行改性,制得巯基改性沸石。研究了吸附剂用量、pH值、温度、Hg^2+浓度和吸附时间对沸石和巯基改性沸石吸附Hg^2+的影响,并进一步研究了吸附机理。结果表明,巯基改性沸石吸附Hg^2+受pH值、温度的影响较小,吸附机制主要是沸石表面的硫与Hg^2+的化学反应。而天然沸石对Hg^2+的吸附主要是离子交换作用,受温度、pH值等的影响较大,随温度的升高吸附量下降。整个吸附过程以较快的速度进行。天然沸石在吸附时间为1h、巯基改性沸石在0.5h时基本达到吸附平衡。吸附条件试验和Langmuir等温吸附模型都表明,巯基改性沸石对Hg^2+的吸附能力得到了很大的提高,吸附容量由8.06mg/g提高到19.88mg/g,提高了146.65%。  相似文献   

13.
MCM-41介孔分子筛的合成及其对铜离子的吸附性能   总被引:1,自引:0,他引:1  
以微硅粉为硅源,CTAB和PEG-6000为模板剂,合成MCM-41介孔分子筛。采用XRD、N2吸附-脱附曲线、FT—IR以及TEM表征了其结构、比表面积、孔径分布及晶体形貌,并且以该样品为吸附剂,对含Cu2+的溶液进行了静态吸附实验。结果表明,以微硅粉为硅源成功合成了具有典型六方排列孔道结构的MCM-41,其比表面积为869.5m。/g,孔容为0.97cm3/g,平均孔径为3.3nm;溶液pH为5—6时,MCM-41对Cu2+的去除效果最好;MCM-41对Cu3+的最大吸附吸附容量36.3mg/g;MCM-41对Cu2+的吸附性能符合Langmuir吸附方程的特征。动力学研究表明,该过程符合准二级动力学模型。  相似文献   

14.
硅质磷块岩对水溶液中镉离子的吸附实验结果表明,硅质磷块岩对水溶性镉离子具有良好的去除效果,主要影响因素有介质的酸度、作用时间、镉离子的初始浓度和样品用量.在pH=6,作用时间为15 min,初始Cd2+浓度为30mg/L的实验条件下,硅质磷块岩对镉离子的去除率可达98%,有可能利用动态法进行工业废水的连续处理.初步研究结果显示,磷块岩对水溶性镉离子的吸附作用符合Langmuir等温吸附模型,不同产地的硅质磷块岩S1和S2对镉离子的最大吸附容量分别为4.43 mg/g和3.88 mg/g.  相似文献   

15.
Synthetic crystalline hydrous ferric oxide (CHFO) (particle size 0.14 to 0.29 mm) has been used systematically for adsorptive chromium(VI) removal from contaminated water. Batch experiments were performed as a function of pH, contact time, solute concentration, and regeneration of adsorbents. Column experiments were performed for breakthrough points in the presence and absence of other ions and treatment of industrial effluent. The optimum pH range was 2.0 to 4.0. The adsorption kinetic data could be described well by both second-order and pseudo-first-order models. The isotherm adsorption data at 30 +/- 2 degrees C obeyed the Langmuir model best. The monolayer adsorption capacity was 35.7 mg/g. Chromium(VI)-rich CHFO could be regenerated up to 89 +/- 1% with 2.0 M sodium hydroxide. Regenerated column reuse showed a decrease (10 to 12%) in breakthrough capacity. Finally, the CHFO- (dried at 300 degrees C) packed column was used for the recovery (98.5 +/- 1.0%) of chromium(VI) from contaminated industrial waste effluent of Hindustan Motor Limited (Hooghly, West Bengal, India).  相似文献   

16.
天然和巯基改性沸石吸附水溶液中重金属Hg2+的特征研究   总被引:6,自引:3,他引:3  
为了提高沸石对汞的吸附性,利用半胱胺盐酸盐对天然斜发沸石进行改性,制得巯基改性沸石。研究了吸附剂用量、pH值、温度、Hg2+浓度和吸附时间对沸石和巯基改性沸石吸附Hg2+的影响,并进一步研究了吸附机理。结果表明,巯基改性沸石吸附Hg2+受pH值、温度的影响较小,吸附机制主要是沸石表面的硫与Hg2+的化学反应。而天然沸石对Hg2+的吸附主要是离子交换作用,受温度、pH值等的影响较大,随温度的升高吸附量下降。整个吸附过程以较快的速度进行。天然沸石在吸附时间为1 h、巯基改性沸石在0.5 h时基本达到吸附平衡。吸附条件试验和Langmuir等温吸附模型都表明,巯基改性沸石对Hg2+的吸附能力得到了很大的提高,吸附容量由8.06 mg/g 提高到19.88 mg/g,提高了146.65%。  相似文献   

17.
Chojnacka K 《Chemosphere》2005,59(3):315-320
The paper discusses sorption of Cr(III) ions from aqueous solutions by animal bones. Animal bones were found to be an efficient sorbent with the maximum experimentally determined sorption capacity in the range 29-194 mg g(-1) that depended on pH and temperature. The maximum experimentally determined sorption capacity was obtained at 50 degrees C, pH 5. Batch kinetics and equilibrium experiments were performed in order to investigate the influence of contact time, initial concentration of sorbate and sorbent, temperature and pH. It was found that sorption capacity increased with increase of Cr(III) concentration, temperature and initial pH of metal solution. Mathematical models describing kinetics and statics of sorption were proposed. It was found that process kinetics followed the pseudo-second-order pattern. The influence of sorbent concentration was described with Langmuir-type equation and the influence of sorbate concentration was described with empirical dependence. The models were positively verified.  相似文献   

18.

Adsorptive removal of copper by activated carbon derived from modified rice husk (ACRH) was studied in the presence and absence of magnetic field (MF). The ACRH was prepared from the normal rice husk treated by NaOH solution and subsequent pyrolysis at 450 °C in the absence of oxygen. The physicochemical properties of ACRH's were determined before and after the adsorption process to delineate the adsorption mechanism. The BET analysis confirmed that the fabricated ACRH has a specific surface area of 8.244 m2/g with a mesopore to micropore ratio of 0.974. It was observed that the micropore structure gradually replaced the mesopores, and the surface area of the micropore increased (from 0.9219 to 4.1764 m2/g), and the pore diameter was also decreased from 180.381 to 46.249 Å after pyrolysis. The CHNO/S test result reveals that the carbon content was increased from 42 to 67.8% in the ACRH after pyrolysis. The batch sorption studies were performed by varying the initial adsorbate concentration, temperature, agitation speed, pH, adsorbent dose and contact time for magnetic and non-magnetic conditions to analyze the effect of the magnetic field. The univariate studies show that the maximum experimental adsorption capacity was 4.522 mg/g and 3.855 mg/g, respectively, for these two conditions (representing the magnetic impact) at 25 °C with an adsorbent dose of 2 g/L and an agitation speed of 150 rpm. It was also observed that the removal efficiency was 94.55% and 77.96% (magnetic and non-magnetic condition) at pH 7 with a concentration of 10 mg/L in 2 h. The test result on the impact of exposure time on the magnetic field suggested that the magnetic memory influenced the removal efficiency; after 40 to 60 min, the maximum removal efficiency was achieved, around 80 to 90%. The pseudo-second-order kinetic model was best fitted with the experimental data with a rate constant as 0.1749 and 0.1006 g/mg/min for these two conditions. The Temkin model delineates the adsorption isotherm suggesting the heat generated during the adsorption process is linearly abate with the coverage of the surface area of the adsorbent. The thermodynamic model confirms that the copper adsorption is spontaneous (ΔG = ? 3.91 kJ/mol and ? 6.02 kJ/mol), wherein the negative enthalpy value (ΔH = ? 36.74 kJ/mol and ? 25.74 kJ/mol) suggested that the process is exothermic irrespective of magnetic interference. The significant enhancement of copper removal was observed by incorporating the magnetic field, showing an increase in sorption capacity by 17.48% and a reduction of reaction time by 88.12%.

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19.
实验通过间歇吸附方式研究了核桃壳粉对水溶液中Pb^2+的吸附特性,探讨了核桃壳粉粒径及用量、溶液pH、Pb^2+初始浓度等参数对吸附的影响,并讨论了吸附过程的热力学和动力学特征。结果表明,核桃壳粉对Pb^2+吸附的最佳pH为5.0,去除率随吸附剂粒径的减小、用量的增加、Pb^2+初始浓度的减小而增加。优化实验条件下,0~0.3mm15g/L的吸附剂在298K时,对pH=5的50mL50mg/LPb^2+溶液的去除率达96.98%。核桃壳粉对Pb^2+的吸附等温线符合Sips模型,在283、293和303K的最大吸附量分别为18.25、18.27和20.94mg/g。吸附过程是放热的、混乱度减小的自发过程,且符合准二级动力学模型。吸附速率常数随温度升高而减小,在293和303K时分别在90和120min基本达到平衡。结合FTIR和SEM手段发现核桃壳对Pb^2+的吸附以物理吸附为主,同时包括离子交换、螯合等化学吸附以及颗粒内扩散步骤,是一个复杂的过程。  相似文献   

20.

Pyrolysis of waste materials to produce biochar is an excellent and suitable alternative supporting a circular bio-based economy. One of the properties attributed to biochar is the capacity for sorbing organic contaminants, which is determined by its composition and physicochemical characteristics. In this study, the capacity of waste-derived biochar to retain volatile fuel organic compounds (benzene, toluene, ethylbenzene and xylene (BTEX) and fuel oxygenates (FO)) from artificially contaminated water was assessed using batch-based sorption experiments. Additionally, the sorption isotherms were established. The results showed significant differences between BTEX and FO sorption on biochar, being the most hydrophobic and non-polar contaminants those showing the highest retention. Furthermore, the sorption process reflected a multilayer behaviour and a relatively high sorption capacity of the biochar materials. Langmuir and Freundlich models were adequate to describe the experimental results and to detect general differences in the sorption behaviour of volatile fuel organic compounds. It was also observed that the feedstock material and biochar pyrolysis conditions had a significant influence in the sorption process. The highest sorption capacity was found in biochars produced at high temperature (>?400 °C) and thus rich in aromatic C, such as eucalyptus and corn cob biochars. Overall, waste-derived biochar offers a viable alternative to be used in the remediation of volatile fuel organic compounds from water due to its high sorption capacity.

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