Chitin derived biochar as an alternative adsorbent to treat colored effluents containing methyl violet dye

Chitin was used to prepare an alternative, eco–friendly and low–cost adsorbent by a simple pyrolysis process. The adsorbent, named chitin derived biochar, was characterized and applied to treat colored effluents containing methyl violet dye (MV). Pyrolysis using N₂ flow rate of 0.25 L min^?1, heating rate of 10 °C min^?1 until 800 °C was suitable to prepare a chitin derived biochar with good characteristics. Chitin derived biochar presented surface area of 275.0 m² g^?1. The MV adsorption on the chitin derived biochar was favored in alkaline conditions and ambient temperature. The adsorption process presented fast kinetics and, the maximum adsorption capacity was higher than 1000 mg g^?1. Chitin derived biochar can be used for 7 consecutive adsorption/desorption cycles maintaining the same adsorption capacity. Also, the material was suitable to treat colored effluents, reaching color removal percentage of 95%. In brief, it was demonstrated that chitin derived biochar is a low–cost and efficient material to treat colored effluents.     

Nitrogen-rich melamine-based carbon nanosheets prepared via polyvinyl pyrrolidone/ammonia chloride-mediate strategy as an excellent adsorbent for methylene blue adsorption

The removal of the methylene blue (MB), a cationic azo dye, in water is highly demanded due to its harmful effects on human health. In this study, the nitrogen-doped carbon nano-sheet was prepared as the adsorbent for MB using the efficient one-pot pyrolysis of melamine in the presence of NH₄Cl and PVP. During the heat-treatment, the PVP interacted with melamine forming hydrogen-bond, which would not only elevate the melamine deamination process but also prohibit the melamine polymerization, which led to the formation of the layered structure. The addition of NH₄Cl in the pyrolysis mixture would favor the formation of crumpled graphene-like-structure. The prepared materials showed a very high adsorption capacity of MB (348.2 mg/g), which is much higher than many other materials. Such a high adsorption capacity was likely due to its unique graphene-like structure, high N doping with a high content of pyridinic N and graphitic N, and large specific surface area. Moreover, the material was successfully recycled with only a slight decrease in the removal efficiency after 5 cycles.     

改性聚丙烯单宁吸附材料的制备与表征

以聚丙烯无纺布为基材,表面紫外光诱导接枝丙烯酸,又依次通过酰胺化、酰肼化、叠氮化,以及紫外光辐照偶联明胶,得到吸附单宁性能较好的改性材料。通过质量法、傅里叶变换红外光谱、热重/差热及扫描电镜等对基材、中间产物及最终产物进行了官能团测定、结构表征和吸水性能测定,结果表明各步反应均按预期引入了目标官能团,所制备的改性材料对单宁的最大吸附量为84.30mg/g。     

氧化镁真空碳热还原过程焦煤的热解行为研究

焦煤的热解经历干燥阶段、胶质体阶段和焦炭生成三个阶段,第二阶段焦煤失重较多。常压条件下焦煤热解时固定炭损失较多,孔隙度随温度和时间的增加而增加,500℃热解30 min后胶质体数量较少,物料内部变化不大;真空条件下煤热解时固定炭不损失,孔隙度随温度的升高而降低,且随着时间的延长升高,60 min后降低,500℃热解30 min可生成较多数量的胶质体,碳元素和镁元素分布趋于均匀。用焦煤做还原剂进行氧化镁真空碳热还原可以得到较纯净的金属镁,没有发生喷料现象。焦煤具有良好的黏结性和结焦性,适于做还原剂。     

聚碳硅烷/纳米钴粉的热裂解研究

本文运用ＩＲ、ＸＲＤ和ＴＧ等分析手段研究了掺混纳米钴粉的聚碳硅烷的热裂解过程。发现热裂解过程可分为有机硅聚合物转化为无机无定形态和无定形态生长为微晶态两个过程，较慢的升温速率有利于得到高的陶瓷产率。钴在热裂解产物中的主要存在形态是ＣｏＳｉ。纳米钴粉的引入促进了热裂解过程中β－ＳｉＣ晶粒的生长，对其催化机理做了初步探讨。     

葡萄糖醛酸功能化双介孔硅对胆红素的高效吸附研究

胆红素是由衰老及异常红细胞被吞噬、血红蛋白分解代谢产生的一种生物活性物质。采用具有小孔径和较大孔径两种介孔孔道的双介孔硅作为基底材料,并用葡萄糖醛酸对双介孔硅进行功能化,以实现对胆红素的选择性吸附。研究了吸附时间、温度、初始浓度、血清蛋白、离子强度对胆红素吸附的影响。实验结果表明,葡萄糖醛酸化双介孔硅对胆红素的吸附快速、高效,吸附平衡为15 min,最大吸附量为(246.78.3)mg/g,血清蛋白的存在对胆红素吸附的影响不大。胆红素吸附符合二级吸附动力学模型和Langmuir等温吸附模型。     

Water-soluble magnetic-graphene nanocomposites: Use as high-performance adsorbent for removal of dye pollutants

In this study, the water-soluble magnetic-graphene nanocomposites (Fe₃O₄@GNs-SO₃H) were fabricated via a simple and efficient approach. The water-soluble magnetic-graphene nanocomposites were applied as an effective adsorbent for removal of organic dye, malachite green, from aqueous solution. It is noteworthy that the nanocomposites displayed good water-dispersibility, rapid absorption rate, high absorption capacity, and convenient magnetic separation. Furthermore, the novel adsorbent could be recovered and recycled for 15 consecutive trials without significant loss of its activity.     

NiFe2O4 nanomagnets prepared through a microwave autocombustion route as an efficient recoverable adsorbent for 2-nitrophenol removal

Nickel ferrite nanoparticles prepared by a microwave-assisted autocombustion method with different fuels and microwave powers were used as bare adsorbents for 2-nitrophenol removal from aqueous solutions. Characterization of the as-prepared samples revealed a fundamental variety with respect to their size and surface area. Meanwhile, the crystal phase, functional groups, surface polarity, and magnetic properties remained almost the same. After electing the most efficient adsorbent based on batch experiments, pH influence was established and optimized. Afterward, equilibrium studies were conducted. The kinetic models and adsorption isotherms further facilitated a better understanding of the adsorption mechanism that comprised mainly the multilayered condensation of 2-nitrophenol molecules through the hydrogen bonding.     

铬粉在裂解聚碳硅烷制备陶瓷材料中的应用

研究了Cr粉在以聚碳硅烷（PCS）为先驱体裂解制备SiC陶瓷材料中的应用。结果表明,Cr在较低的温度下减慢PCS的裂解反应,在较高的温度下则加剧PCS的裂解,且能增加先驱体的陶瓷产率,降低先驱体在裂解 的线性收缩率和气孔率,提高陶瓷材料性能。     

Defluoridation of groundwater using brick powder as an adsorbent

Defluoridation of groundwater using brick powder as an adsorbent was studied in batch process. Different parameters of adsorption, viz. effect of pH, effect of dose and contact time were selected and optimized for the study. Feasible optimum conditions were applied to two groundwater samples of high fluoride concentration to study the suitability of adsorbent in field conditions. Comparison of adsorption by brick powder was made with adsorption by commercially available activated charcoal. In the optimum condition of pH and dose of adsorbents, the percentage defluoridation from synthetic sample, increased from 29.8 to 54.4% for brick powder and from 47.6 to 80.4% for commercially available activated charcoal with increasing the contact time starting from 15 to 120 min. Fluoride removal was found to be 48.73 and 56.4% from groundwater samples having 3.14 and 1.21 mg l(-1) fluoride, respectively, under the optimized conditions. Presence of other ions in samples did not significantly affect the deflouridation efficiency of brick powder. The optimum pH range for brick powder was found to be 6.0-8.0 and adsorption equilibrium was found to be 60 min. These conditions make it very suitable for use in drinking water treatment. Deflouridation capacity of brick powder can be explained on the basis of the chemical interaction of fluoride with the metal oxides under suitable pH conditions. The adsorption process was found to follow first order rate mechanism as well as Freundlich isotherm.     

Oxygen-defective MnO2 decorated carbon nanotube as an effective sulfur host for high performance lithium sulfur battery

The incorporation of sulfur with multifunctional conductive host material has been regarded as a promising strategy to improve the sulfur utilization and mitigate the polysulfides diffusion for high-performance Li-S battery. Herein, an oxygen-defective MnO₂ nanoparticles modified carbon nanotube composite (CNT/OD-MnO₂) has been proposed as multifunctional sulfur host materials. In the CNT/OD-MnO₂, the continuous CNT frameworks provide abundant conduction paths of electrons, and the oxygen-defective MnO₂ nanoparticles can accelerate the adsorption and conversion process of polysulfides during the charge–discharge process. As expected, the derived sulfur cathode exhibits superior electrochemical properties with the assistance of CNT/OD-MnO₂. Compared with the CNT/MnO₂-S (61.8%) and CNT-S (38.8%) cathodes, the CNT/OD-MnO₂-S cathode delivers a higher capacity retention of 81.3% even after 300 cycles. These results confirm the promising application of CNT/OD-MnO₂ as an effective sulfur host material for advanced Li-S battery.     

改性膨润土对溶液中Co2+、Mn2+的吸附研究

以膨润土为原材料,盐酸为改性剂,制备改性膨润土。研究了改性膨润土的制备条件,其对重金属Co2+、Mn2+的吸附性能及对苯二甲酸(PTA)工业中的副产品对甲苯甲酸对吸附的影响。实验结果表明,盐酸的最佳改性浓度为1.5mol/L,改性膨润土在40℃的吸附能力最好,可达到12～14mg/g,经过热力学分析得出,改性膨润土对钴离子、锰离子的吸附方式均符合Langmuir吸附模型,PTA工业中的副产品对甲苯甲酸对吸附没有影响。     

Effect of Fe2O3 addition on the ferroelectricity of sodium and lithium vanadates

Spontaneous polarization and coercivity of sodium and lithium vanadates were found to be remarkably dependent on the solid solutions formed between the respective vanadates and Fe₂O₃. The decreasing trend inP _s and the depression ofT _c observed for increasing concentrations of the offvalent impurity were attributable to the formation of defective grain boundary layers of low electric polarization.     

Removal of phosphate species from solution by adsorption onto calcite used as natural adsorbent

Phosphates are very important basic materials in agricultural and other industrial applications. Phosphorus is often present in low concentrations in wastewater, almost solely in the form of organic and inorganic phosphates (ortho- and poly-phosphates). The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. The usual methods of treatment are either biological or physicochemical by sedimentation. This paper studies the removal of phosphate species by adsorption onto calcite used as natural adsorbent. The phosphate solutions were prepared artificially by adding certain quantities of K2HPO4 in water. The effect of equilibrium pH, phosphate/mineral ratio and contact time was studied. The results showed that pH plays an important role in the removal of phosphate species from solution, with removal being more efficient in the basic pH region. The experimental results also show that adsorption is also efficient for high ratios phosphate/adsorbent. Finally, the adsorption process is time dependent. Based on the experimental results a possible mechanism of phosphate removal onto calcite surface is proposed. As a general conclusion, phosphate species seem to be efficiently removed from solutions using calcite as natural adsorbent. In addition, the adsorption product can be used as fertilizer for acid soils.     

装甲车辆车载变压吸附制氧装置性能的试验分析

为解决高原部队缺氧问题,更好地满足部队战斗、训练的需要,对两台装甲车辆车载变压吸附制氧装置的样机进行低压舱模拟试验。测试制氧装置性能,分析产氧浓度、输出流量、入口压力和海拔高度之间的关系以及耗电量对样机性能的影响。测试结果表明,产氧浓度随海拔高度的升高而降低,随着输出流量的增大而减小,随入口压力的增加而增加。样机ZJS-2的功耗比ZJS-1平均高出300W。样机的产氧性能基本满足系统工程生理学防护要求和国军标GJB114—1986《急性缺氧防护生理要求》。     

装甲车辆车载变压吸附制氧装置性能的试验分析

为解决高原部队缺氧问题，更好地满足部队战斗、训练的需要，对两台装甲车辆车载变压吸附制氧装置的样机进行低压舱模拟试验。测试制氧装置性能，分析产氧浓度、输出流量、入口压力和海拔高度之间的关系以及耗电量对样机性能的影响。测试结果表明，产氧浓度随海拔高度的升高而降低，随着输出流量的增大而减小，随入口压力的增加而增加。样机ZJS-2的功耗比ZJS-1平均高出300W。样机的产氧性能基本满足系统工程生理学防护要求和国军标GJB 114-1986《急性缺氧防护生理要求》。     

Bis-phosphonated carbon nanotubes: One pot synthesis and their application as efficient adsorbent of mercury

Effective, one-pot method of CNTs phosphonylation is presented. Cheap and readily available reagents are used, so the process can be easily transferred to large-scale production. The product was analyzed using spectroscopic methods (FTIR, UV-vis, XPS). Thermal properties of the bis-phosphonated nanotubes are reported for the first time. Newly obtained material was tested as an adsorbent for mercury removal from water. The sorption capacity for newly developed adsorbent was as high as 223.7 mg/g. The adsorption kinetics were studied within framework of Lagergren model, and Langmuir and Freundlich isotherms have been described. The effect of pH on the adsorption process has been evaluated and the optimal environmental conditions were determined to be neutral. The presence of bivalent ions Cd²⁺, Ni²⁺ in the solution did not affect adsorption efficiency of novel materials.     

Magnetite nanoparticles as adsorbent material for Cu2+ ions from aqueous solution

Cu²⁺ ions can cause serious injuries to human health, at both high and low concentrations. Therefore, it is important not only to remove Cu²⁺ ions from aqueous media, but also to develop analytical methods for their accurate determination at low concentrations. Magnetite is one of the most used sorbents for Cu²⁺ removal. This work aims at synthesizing magnetite nanoparticles and at evaluating their adsorption capacity toward Cu²⁺ ions in aqueous solution by means of atomic absorption spectroscopy. Magnetite nanoparticles were characterized by means of a vibrational magnetometer, Fourier transformer infrared spectrum (FTIR), x-ray diffraction (XRD) and Thermal gravimetric analysis (TGA). Magnetic nanoparticles showed Ms values of 52 and 62?emu/g. By taking into consideration the precipitation of Cu(OH)₂ as a function of pH in the evaluation of the adsorption capacity of magnetite, we found that the maximum Cu²⁺ adsorption occurs at pH?=?7 and that the adsorption equilibrium of the two samples is reached at 490 and 445?min. The use of blank solution avoids the overestimation of the adsorption capacity due to the presence of insoluble Cu(OH)₂. Finally, two models are considered as a liquid/solid phase reaction, pseudo-first- and pseudo-second-order reaction. Batch adsorption kinetics agrees with a pseudo-second-order model, suggesting that chemisorption is the rate-limiting step.     

Removal of copper from aqueous solution using newspaper pulp as an adsorbent

Newspaper pulp was found to be a potential adsorbent for removal of copper from aqueous medium. Detail adsorption study of Cu on newspaper pulp was investigated. Batch adsorption study was carried out as a function of contact time, adsorbent dose, temperature (303-323 K). The experimental data was analyzed using Freundlich, Langmuir, Dubinin-Radushkevich (D-R) and Redlich-Peterson (R-P) isotherm models. It was found that Freundlich, Langmuir and R-P models fitted well. pH variation study revealed that the adsorption increased with increase in pH of the solution. Maximum loading capacity was found to be 30 mg g(-1) at 20 mg L(-1) of initial Cu concentration. Adsorption data were analyzed using two kinetic models, Lagergren first order and pseudo second order. It was observed that pseudo second order represented the best correlation. Langmuir isotherm was used to obtain the thermodynamic parameters such as free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) of adsorption. The negative value of free energy and positive value of enthalpy change indicate that the adsorption of Cu on newspaper pulp is a spontaneous process and endothermic. The results of activation energy also confirmed that the adsorption of Cu on newspaper pulp is physical in nature. Present investigation emphasized that newspaper pulp may be utilized as a low cost adsorbent for copper removal.