Synthesis of Activated Carbon from Polyethylene Terephthalate(PET)Plastic Waste and Its Application for Removal of Organic Dyes from Water

Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are discarded,they can cause serious harm to the environment and human health.In this study,PET plastic waste was used to create activated carbon using a physical activation process that involved using CO2 gas.The researchers investigated the effects of different temperatures,carbonization,and activation times on the resulting activated carbon’s surface area.The activated carbon was then analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),FTIR,and BET.The activated carbon created from PET plastic waste showed excellent absorption properties for methylene blue in aqueous solutions across a wide range of pH levels.By creating activated carbon from plastic waste,not only are environmental issues addressed,but high-value activated carbon is produced for environmental remediation purposes.

Characteristic and mercury adsorption of activated carbon produced by CO_2 of chicken waste

Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process （drying at 200℃, pyrolysis in N2 atmosphere, followed by CO2 activation） was used for the production of activated samples. The effects of carbonization temperature （409-4500℃）, activation temperature （700-900℃）, and activation time （1-2.5 h） on the physicochemical properties （weight-loss and BET surface） of the prepared carbon wereinvestigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon （Darco LH） （Hg^v： 38.7% vs. 53.5%, Hg^0： 50.5% vs. 68.8%）, although its surface area is around 10 times smaller, 89.5 m^2/g vs. 862 m^2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.

Waste Activated Sludge Alkaline Fermentation Liquid as Carbon Source for Biological Nutrients Removal in Anaerobic Followed by Alternating Aerobic-Anoxic Sequencing Batch Reactors

Activated sludge process has been widely used to remove phosphorus and nitrogen from wastewater. However,the nitrogen and phosphorus removal is sometimes unsatisfactory due to the low influent COD.Another problem with the activated sludge process is that large amount of waste activated sludge is produced,which needs further treatment.In this study,the waste activated sludge alkaline fermentation liquid was used as the main carbon source for phosphorus and nitrogen removal under anaerobic followed by alternating aerobic-anoxic conditions,and the results were compared with those using acetic acid as the carbon source.The use of alkaline fermentation liquid not only affected the transformations of phosphorus,nitrogen,intracellular polyhydroxyalkanoates and glycogen, but also led to higher removal efficiencies for phosphorus and nitrogen compared with acetic acid.It was observed that ammonium was completely removed with either alkaline fermentation liquid or acetic acid as the carbon source. However,the former resulted in higher removal efficiencies for phosphorus(95%)and nitrogen(82%),while the latter showed lower ones(87%and 74%,respectively).The presence of a large amount of propionic acid in the alkaline fermentation liquid was one possible reason for its higher phosphorus removal efficiency.Exogenous instead of endogenous denitrification was the main pathway for nitrogen removal with the alkaline fermentation liquid as the carbon source,which was responsible for its higher nitrogen removal efficiency.It seems that the alkaline fermentation liquid can replace acetic acid as the carbon source for phosphorus and nitrogen removal in anaerobic fol- lowed by alternating aerobic-anoxic sequencing batch reactor.

Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology （RSM） technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.

Preparation of Solid Waste-Based Activated Carbon and Its Adsorption Mechanism for Toluene

Regenerated activated carbon(RAC)samples were prepared by carbon activation using waste activated carbon from solid waste resources as the carbon source precursor coupled with adding alkaline additives,and then were further modified by potassium ferrate to finally prepare high-performance carbon for VOCs adsorption.At the same time,the samples before and after modification were systematically studied through characterization techniques such as SEM,Raman spectrometry,FT-IR,XPS,and dynamic/static adsorption.The results showed that the specific surface area and pore volume of the RAC after modification by the strong oxidant potassium ferrate increased by 1.4 times;the degree of defects was enhanced and the content of oxygen-containing functional groups on the surface increased significantly.Among them,the sample modified with potassium ferrate for 24 h had the best dynamic toluene adsorption performance(375.5 mg/g),and the dynamic adsorption capacity was twice that of the original sample(192.8 mg/g).The static adsorption test found that the maximum adsorption capacity of RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h was 796 mg/g,which indicated that the potassium ferrate modification treatment could significantly increase the VOCs adsorption performance of RAC.In addition,through consecutive toluene adsorption-desorption cycle tests,it was found that the RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h sample still retained 91%of adsorption activity after the fifth regeneration cycle.This indicates that RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h has good cycle stability and great application value for the efficient purification of industrial waste VOCs gas.

Adsorption of Indigo Carmine Dye by Composite Activated Carbons Prepared from Plastic Waste (PET) and Banana Pseudo Stem

This study is on the adsorption of indigo carmine dye by composite activated carbons prepared from banana pseudo stems and plastic waste. The activated carbons named TB1P1, TB1P1h and TB2P1 were obtained by pyrolysis at 700°C under steam of raw materials at different ratios (1:1 and 2:1). They were characterized by different techniques such as SEM/EDX, Raman Spectroscopy, FTIR, XRD, TGA/DTA and BET/BJH. Analyses indicate amorphous structures with specific surface areas of 424.37;385.45 and 338.84 m2/g for TB1P1, TB1P1h and TB2P1 respectively. The study of the adsorption of indigo carmine dye by these adsorbents was carried out by varying parameters such as contact time, mass of adsorbent and initial concentration of the dye. The maximum retention is 94.71%, 86.18% and 84.17% for TB1P1, TB1P1h and TB2P1 respectively after 60 min of stirring, for a pH = 4.6 using 0.6 g of adsorbents. The adsorption of indigo carmine follows well, the Langmuir model, with the most suitable kinetics as pseudo second order.

Production of Activated Carbon and Characterization from Snail Shell Waste (<i>Helix</i><i>pomatia</i>)

Snail shell waste (Helix pomatia) has been evaluated as raw material for the preparation of activated carbon using ZnCl2 and CaCl2 with the temperature ranging from 500°C to 800°C. The activated carbon prepared was characterized, showing effect of temperature on ash content, pore volume and porosity. The adsorption isotherm for methylene blue was carried out on the activated carbon in a batch study. The adsorbent exhibited excellent adsorption for methylene blue. The experimental data were used for both Langmuir and Freundlich models. The adsorption coefficients of Langmuir isotherm were found to be 0.996 and 0.957 for CaCl2 and ZnCl2 while 0.969 and 0.962 were obtained for the Freundlich isotherm respectively. The value of RL was found to be 0.75 and 0.38 for samples CC and ZZ respectively, which is an indication that activated carbon impregnated with CaCl2 and ZnCl2 is favourable for adsorption of methylene blue under the conditions used in this study.

Adsorption and Kinetic Study of Activated Carbon Produced from Post-Consumer Low-Density Polyethylene (LDPE) Wastes

Post-consumer polymeric wastes in form of low-density polyethylene (LDPE) can now be considered suitable as a precursor for the synthesis of low-cost activated carbon (AC). This study produced AC from LDPE using sulphuric acid (H2SO4) and potassium hydroxide (KOH) as the activating agent. The reaction conditions for pyrolysis were varied in the range of 0.50 - 2.00 M, 400°C - 500°C, and 45 - 60 minutes. Physico-chemical investigations reveal that AC yield is significantly dependent on both carbonization temperatures and time. The obtained optimum values of 446.50°C and 51.09 mins gave a yield of 24% for the base-activated carbon. The high iodine numbers obtained strongly indicate the presence of large surface area and pore volumes is further confirmed using the Scanning Electron Microscopy (SEM) analysis which reveals the presence of pores on the external surface of the carbons. Fourier Transform Infrared Technique (FTIR) analysis further shows that the synthesized compounds are purely carbon with rich oxy-gen-surface complexes on the surface which is as a result of the introduction of the chemical oxidizing agents. The produced carbons were found to have high adsorption affinity for selected inorganic ions which are: Mn7+, Co2+, and Cr6+. Adsorption isotherm results show the adsorption process to be favourable with the Langmuir isotherm parameter RL having values of <1, while the Freudlich adsorption model was found to perfectly fit the data at selected adsorbent dosages and adsorbate concentrations. The pseu-do-second-order model provides the best correlation for the kinetic analysis. The acid-activated carbon was found to have better adsorption capacities than the base-activated carbon.

Heteroatomic Modification of Solid-Waste-Based Mesoporous Carbon for Volatile Organic Compound Adsorption

Solid-waste-based activated carbon(AC)was utilized as a carbon source to synthesize a series of carbon-based functional material RAC-X(X=P and S,where P and S denote phosphoric and sulfuric acids,respectively).The toluene adsorption capacities of the regeneration AC(RAC)samples can be significantly improved by adopting the heteroatomic modification strategy.RAC-P and RAC-S have the same specific surface area(1156 m^(2)/g)and similar porous structures.However,they have different toluene adsorption capacities,with 316.22 mg/g for RAC-P and 460.12 mg/g for RAC-S,which are 1.6 and 2.4 times greater than that for RAC.The X-ray photoelectron spectroscopy measurements showed that the increase in the amount ofπ–π^(2)chemical bond over the AC surface results in the improvement of the toluene adsorption performance.The density functional theory results showed that the S-containing functional groups loaded near the defect sites of RAC-S promote toluene adsorption.Moreover,reusability tests showed that RAC-S still retains 86%of its adsorption activity after four consecutive adsorption–desorption experiments.This indicates that the heteroatomic modification method affords excellent toluene adsorption performance and recycling practicability,which not only is beneficial for achieving the rational utilization of solid waste resources but also provides a practical method for the efficient elimination of volatile organic compounds.

Composite Activated Carbon from Canarium schweinfurthii/Polyethylene Terephthalate: Adsorption Test of Rhodamine B Dye Removal in Aqueous Solution

The present work deals on one hand with the valorization of wastes plastics, polyethylene terephthalate (PET) and Canarium schweinfurthii (CS) for the preparation of polyethylene terephthalate activated carbon (PETAC) and Canarium schweinfurthii/polyethylene terephthalate activated carbon (CS/PETAC). These adsorbents, on the other hand, were used for removal Rhodamine B (RhB) in an aqueous solution. PET and CS precursors were subjected to thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC). Meanwhile PETAC and CS/PETAC were characterized using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray fluorescence (XRF), Fourier transformed infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption (N2-BET). The N2-BET results revealed an increase of the specific surface area from 6.75 m2/g to 1282.0 m2/g for PETAC and CS/PETAC. The results of characterization indicated the key role played by plastic wastes to enhance the structural and functional properties of CS/PETAC. The RhB removal from the aqueous solution onto PETAC and CS/PETAC was found to be independent of pH, with an optimal contact time of RhB removal within 10 min for materials. The non-linear adsorption isotherm data for the adsorption process showed that the Langmuir and Freundlich models best fitted the RhB adsorption onto PETAC meanwhile only the Freundlich adsorption isotherm gave the best fit for CS/PETAC according to the correlation coefficient value closed to unity. The pseudo-first and pseudo-second-order kinetic models best described the RhB dye removal on both adsorbents. Additionally, the Elovich model confirmed that chemisorption was the main mechanism followed. These findings proved that CS seeds and PET wastes are low-cost precursors that should be given an added value by transforming them into an outstanding carbon material for dye removal in liquid effluent.

Systematic Analysis of Carbon Dioxide Activation of Waste Tire by Factorial Design

In this study, waste tire was used as raw material for the production of activated carbons through pyrolysis. ＇Fire char was first produced by carbomzation at 550℃ under nitrogen. A two tactortal design was used to optimize the production of activated carbon from tire char. The effects of several factors controlling the activation process, such as temperature （.830-930℃）, time （2-6h） and percentage ot carbon dioxide （70%-100%） were investigated. The production was described mathematically as a function of these three factors. First order modeling equations were developed for surface area, yield and mesopore volume. It was concluded that the yield, BET surface area and mesopore volume of activated carbon were most sensitive to activation temperature and time while percentage of carbon dioxide in the activation gas was a less significant factor.

Effect of preparation methods on the adsorption property of municipal solid waste-based carbon materials

Three different preparation methods including steam physical activation, catalytic carbonation and KOH chemical activation methods were used to prepare municipal solid waste- based carbon materials. The methylene blue （MB） adsorption value was applied to evaluate the adsorption capabilities of the prepared carbon materials. The effects of preparation methods on adsorption capability and yield of products were investigated. The yield of carbon materials with the catalytic carbonation method is the highest, and the KOH activation method is the second level. Considering the adsorption performance, the KOH activation method is much more favorable. Among the different components of municipal solid waste-based carbon materials, the adsorption properties of the single component of paperboard, the double components of tire and paperboard, the triple components of tire, paperboard and polyvinyl chloride （PVC）, and the multi-component mixtures are better than those of other single-, double-, triple- and multi-component mixtures, respectively.

Sustainable Activated Carbons from Agricultural Residues Dedicated to Antibiotic Removal by Adsorption

The. objectives.of this study are to convert at laboratory s.cale agric.ultural residues into activated carbons （AC） with specific properties, to characterize them and to test them in adsorption reactor for tetracycline removal, a common antibiotic. Two new ACs were produced by direct activation with steam from beet pulp （BP-H2O） and peanut hu_lls （PH-H2O） in environmental friendly conditions BP-H2O and PH-H2Opresentcarbon content rangedcarbons with different intrinsic properties.

Activated carbons derived from oil palm empty-fruit bunches: Application to environmental problems

Activated carbons derived from oil palm empty fruit bunches （EFB） were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process, Two types of activation namely; thermal activation at 300, 500 and 800℃and physical activation at 150℃ （boiling treatment） were used for the production of the activated carbons. A control （untreated EFB） was used to compare the adsorption capacity of the activated carbons produced from these processes. The results indicated that the activated carbon derived at the temperature of 800℃ showed maximum absorption capacity in the aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon at 800℃. It was observed that the adsorption capacity was higher at lower values of pH （2-3） and higher value of initial concentration of phenol （200-300 mg/L）. The equilibrium data fitted better with the Freundlich adsorption isotherm compared to the Langmuir. Kinetic studies of phenol adsorption onto activated carbons were also studied to evaluate the adsorption rate. The estimated cost for production of activated carbon from EFB was shown in lower price （USD 0.50/kg of activated carbon） compared the activated carbon from other sources and processes.

Organic carbon dynamics and enzyme activities in agricultural soils amended with biogas slurry, liquid manure and sewage sludge

The application of organic soil amendments is a common practice for increasing soil fertility and soil organic carbon (SOC) content. In recent years, a new product from biogas production, biogas slurry is increasingly applied to agricultural soils, although little is known about its effects on soil properties. In this study, the influence of this new product in comparison with liquid manure and sewage sludge on the organic carbon dynamics and enzyme activities were investigated in two different agricultural soils in short-term incubation studies. As a control, biologically inert sand was also amended with these organic wastes. In sand, biogas slurry degraded to 10.4% within 14 days, while no differences were found between the degradability of liquid manure and sewage sludge with 6.6% and 5.4%, respectively. However, although the degradability of biogas slurry was highest among the organic amendments, liquid manure application resulted in the highest respiration rates in the soil samples. This was likely due to the organic waste borne easily decomposable substrates which were most dominant in liquid manure. Organic waste applications were found to generally increase the activity of numerous enzymes but did not change the soil enzyme patterns. Thus, in general it was shown that the microbial population of the organic wastes will not become prominent when introduced with the manures to soils. Thus, an inoculation with organic waste borne microorganisms could likely be neglected when discussing the extent of organic carbon dynamics after organic waste application to agricultural soils.

弱酸性蓝AS 染料排放的废盐制碳基吸附剂及利用

将染料弱酸性蓝AS(AS)生产排放的含盐废水喷雾干燥后制成废盐,再将其有机污染物煅烧制备成类活性炭吸附剂(LAC),用于AS染料生产过程中产生的洗涤废水的吸附脱色净化,同时回收粗盐NaCl可循环用于AS工业生产的盐析过程。对LAC进行吸附过程动力学、热力学研究,并研究AS染料废水溶液初始浓度、温度及pH对吸附性能的影响。在40 mg/L的AS染料废水中,温度为318 K的条件下,平衡吸附量为29.22 mg/g。在酸性及温度较高时吸附能力较强。Langmuir等温线方程能更好拟合吸附实验结果。另外,采用一锅混合法,添加四水合乙酸镁对LAC进行改性,改性后的吸附剂LACMg0.75比表面积较LAC提升了近5倍,饱和吸附量能够达到550.02 mg/g,较LAC提升了接近20倍。

盾构淤泥质废弃黏土氧化镁固化-碳化试验及碳化机制研究

盾构隧道施工产生的废弃土面临堆放、运输及处理等难题,将原材料丰富、生产耗能少、环境友好的MgO用于废弃土固化处理是一个值得探索的方法。通过改变MgO掺量a_(m)、养护龄期T、碳化时间H研究MgO固化-碳化淤泥质废弃黏土界限含水率w、无侧限抗压强度q_(u)、弹性模量E_(50),结合微观形貌及矿物成分变化规律探讨其固化-碳化机制。结果表明:MgO固化-碳化具有明显的加固土体效果,加固效果随a_(m)、T呈先上升后趋于稳定的趋势,随H呈先上升后下降的趋势;不同a_(m)、T下,碳化4h会使土体塑性指数I_(P)降低57%以上,土体可塑性显著下降;不同a_(m)和T的固化-碳化土q_(u)均在H为4h时取得峰值,最高可达1.4MPa,比碳化前强度提升了220%~350%;固化-碳化反应对土体的E_(50)提升受a_(m)影响较大,当a_(m)超过9%时,碳化4h试样的E_(50)增幅在500%左右;MgO固化-碳化过程中水化产物、碳化产物不断生成和发育,形成网状、花朵聚集状的形貌,填充土颗粒间的孔隙,增强了土颗粒间的胶结作用,土体结构更为密实。该研究为长三角地区土压盾构产生的淤泥质废弃黏土的固化-碳化处理与再利用提供了思路。

废纸制浆造纸废水好氧生物强化增效处理研究

以竹炭为载体制备氮铈掺杂改性且固定化微生物及微量元素的生物增效材料,采用生物强化增效技术对废纸制浆造纸废水的好氧处理进行优化,通过降低生化处理出水浓度来降低深度处理的难度和成本。利用SEM和16S rRNA测序等手段对活性污泥表面形貌及结构和微生物菌落结构进行分析,综合评价了生物强化增效技术对废纸制浆废水好氧生物处理性能的影响。研究结果表明:该技术可以提高污染物生物降解能力,提高生物处理效果。普通生化处理出水COD平均值140 mg/L、氨氮平均值2.3 mg/L,色度平均值260倍,平均COD去除率86.47%、平均氨氮去除率88.83%、平均色度去除率33.33%;同等条件下,生物增效处理出水COD平均值72.2 mg/L、氨氮平均值0.95 mg/L、色度平均值50倍,平均COD去除率93.02%、平均氨氮去除率达到了95.39%、平均色度去除率87.18%,处理效果明显优于普通生化处理。生物增效处理出水采用传统PAC或PFS处理均可达到排放标准,且PFS的处理成本低至0.63元/m^(3);而普通生化处理只能采用芬顿处理才能达到排放标准,且处理成本达3.27元/m^(3)。SEM分析结果显示:生物增效处理的活性污泥絮体结构紧凑,具有更高的生物量;与普通生化处理的污泥相比,生物增效处理的污泥中脱硫杆菌门(Desulfobacterota)和拟杆菌门(Bacteroidota)丰度增加了3.07和2.29个百分点,unclassified_o_PB19属增加了2.96个百分点,说明生物增效材料的投加能帮助一些具备特殊降解功能的微生物创造有利生存环境并激活其生长,提高了反应体系的定向降解能力。

纤维素对活性炭孔结构的影响

为了探讨纤维素对活性炭孔结构的影响,采用废茶、荞麦壳和开心果壳3种生物废弃物作为制备活性炭的原材料,利用活化剂KOH,ZnCl 2,通过改变浸渍比控制活性炭的比表面积和孔结构。结果表明:利用KOH活化的活性炭最佳浸渍比均为2.0;当KOH为活化剂、浸渍比为2.0时,荞麦壳活性炭的BET比表面积和微孔孔容最大,分别达到904.8 m 2·g-1和0.37 cm^(3)·g^(-1),开心果壳活性炭的BET比表面积和微孔孔容分别为746.7 m^(2)·g^(-1)和0.31 cm^(3)·g^(-1),废茶活性炭的BET比表面积和微孔孔容分别为747.8 m 2·g-1和0.28 cm^(3)·g^(-1)。纤维素去除实验的结果表明:纤维素是影响活性炭微孔结构的主要因素。

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents:A comparative study of waste-polymer-based,coal-based activated carbon,and carbon nanotubes

Adsorption of the hydrophobic organic compounds （HOCs） trichloroethylene （TCE）, 1,3-dichlorobenzene （DCB）, 1,3-dirdtrobenzene （DNB） and y-hexachlorocyclohexane （HCH） on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon （F400） and multiwalled carbon nanotubes （MWNT）. The polymer- based activated carbons were prepared using KOH activation from waste polymers： polyvinyl chloride （PVC）, polyethyleneterephthalate （PET） and tire rubber （TR）. Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area （2700 m2/g） and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.