质子化改性壳聚糖吸附硫酸根行为及其光谱分析

壳聚糖(CTS)具有活性基团氨基和羟基,可用作吸附剂。在酸性介质中其氨基容易质子化形成氨基正离子,具有吸附阴离子的能力,同时也导致吸附剂的溶解流失;进行交联处理可提高吸附剂的酸稳定性,但也导致吸附性能的下降。因此可进行氨基保护后进行交联以改善其酸溶液稳定性,再脱去氨基保护剂进行质子化处理以获得较好的对阴离子的吸附性能。以甲醛为氨基保护剂,戊二醛为交联剂,通过反相悬浮法制得交联壳聚糖(CCTS),对其进行质子化制得质子化改性壳聚糖吸附剂(P-CCTS),并首次将该吸附剂用于处理水溶液中的硫酸根离子。通过静态吸附实验,考察了质子化改性壳聚糖对硫酸根的吸附性能;利用X射线能谱元素分析(EDS)和红外光谱分析(FTIR)对该吸附剂的制备以及对硫酸根离子的吸附过程进行了表征,探索了交联反应和吸附反应的发生机理。实验结果表明：质子化改性壳聚糖吸附剂与交联壳聚糖相比,其对硫酸根离子的吸附性能提高了约10倍;甲醛、戊二醛的醛基与壳聚糖的交联反应主要发生在的氨基(—NH₂)和部分一级羟基(C₆—OH)上;质子化过程中交联壳聚糖的氨基与质子化剂形成了氯化壳聚糖氨盐;对硫酸根离子的吸附则主要是质子化氨基上氯离子与硫酸根离子的交换作用。     

分光光度法研究改性粉煤灰对有机磷的吸附性能

常温下,用硫酸铝为改性剂制得改性粉煤灰,以此作为有机磷废水的吸附剂,用分光光度法分析改性粉煤灰对有机磷的吸附性能,并通过XRD对其结构进行表征。结果表明:改性时,盐灰质量比为1∶12;吸附时,改性粉煤灰用量为35g/L、溶液的pH值为8、振荡时间为30min、吸附温度为30℃时,磷的去除率可达97.0%。     

改性粉煤灰净化水中的磷

研究了粉煤灰的浓硫酸改性以及改性后的粉煤灰从水中净化磷的过程.通过实验发现粉煤灰改性后对水中磷的净化效果有显著提高.粉煤灰用浓硫酸进行改性后比表面积从8.8m2/g增加到32.5m2/g.而且用浓硫酸改性后,粉煤灰中的金属离子在酸性条件下部分溶解或完全溶解,导致净化过程中水溶液中金属离子浓度增大.改性粉煤灰净化含磷废水的过程中,存在吸附机理和沉淀机理,但沉淀对磷的净化起主要作用.实验结果表明,改性粉煤灰对磷的净化过程速度较快,5min可以达到最大净化率.在pH 5-9范围内磷净化过程影响不显著.通过实验还发现磷的净化率随吸附剂用量的增加而增加.改性粉煤灰对磷的吸附过程比较符合Langmuir吸附等温线,Langmuir常数Q0为9.15mg·g-1.从吸附磷后的改性粉煤灰的XRD图和SEM图可以发现在磷的净化过程中生成了CaHPO4·2H2O,此外磷也与铁和铝反应形成沉淀.     

壳聚糖富集-火焰原子吸收法测定痕量银

研究了天然高分子吸附剂-壳聚糖对银离子的吸附行为以及在不同pH值、干扰离子存在时对壳聚糖吸附银离子的影响,通过选择最佳吸附条件,建立了壳聚糖富集-火焰原子吸收法测定银的方法。当溶液pH 6.0、流速为1 mL·min-1时,吸附率最高,达96.7%,静态饱和吸附量为97.8 mg·g-1。用1 mol·L-1 H₂SO₄作为洗脱剂,洗脱效果最好。壳聚糖不吸附K+,Na+,Ca2+,Mg2+,Mn2+,富集时可与被测银离子分离,不干扰测定。100 mg·mL-1的Al3+,Cr3+,80 mg·mL-1的Ni2+,Cu2+,Pb2+,Zn2+虽然可被壳聚糖吸附, 但不干扰测定。用此方法对实验室含银(1.83 μg·mL-1)废水中的Ag进行测定,回收率为94.3%。     

高比表面积活性炭对曙红Y染料的吸附

以海南椰树壳为原料通过复合物理活化方法制备出2162.84m2/g的高比表面积活性炭,所得活性炭孔径分布范围为1.1-2.5nm.选择对曙红Y染料进行吸附研究,采用分光光度法考查吸附剂用量、pH值、初始浓度、温度与吸附时间对单组分体系染料的吸附量与脱除效果的影响.结果表明在曙红Y浓度1600g ·m-3、pH为2.02、吸附时间10min、温度318K和吸附剂用量0.05g时脱除率可达99.9％.     

交联壳聚糖预富集火焰原子吸收光谱法测定水中总锰

提出了用交联壳聚糖(CCTS)预富集、火焰原子吸收光谱法测定水中总锰的新方法。研究了CCTS对Mn (Ⅶ)的吸附行为,结果表明：在pH 3.00时,CCTS对Mn(Ⅶ)的吸附率最高,达98%。考察了吸附时间、CCTS用量、温度、样品体积以及共存元素对吸附率的影响;探讨了吸附机理。方法的检出限(3σ)为1.86 μg·L-1,相对标准偏差(RSD)为2.0%(n=10)。用于南湖水和长江水中总锰的测定,结果满意。     

改性壳聚糖吸附剂表征及脱除Hg~0的实验研究

应用VM3000在线测汞仪作为检测手段,在固定床实验台架上,用碘、硫酸和盐酸改性壳聚糖为吸附剂进行脱汞(Hg~0)实验研究。采用傅里叶变换红外光谱(FTIR)和X射线衍射仪(XRD)对吸附剂进行性能表征。结果表明,碘化钾、硫酸(盐酸)和壳聚糖中的氨基发生了化学反应。质子化的壳聚糖更利于吸附碘这一对Hg~0有吸附力的活性位,壳聚糖吸附剂上碘等活性位的存在形态是其脱除汞的关键因素;单质碘改性壳聚糖吸附剂并不能有效地脱除Hg~0;KI和H_2SO_4改性壳聚糖吸附剂120 min内的汞容积量达200μg/g,其初始时刻的最大脱汞效率可达100%。     

分光光度法研究粉煤灰对亚甲基蓝的吸附及其机理研究

以龙岩雁石火电厂粉煤灰对亚甲基蓝进行吸附实验,探讨了改性粉煤灰、粉煤灰用量、吸附时间、温度对亚甲基蓝吸附的影响。当粉煤灰投加量为4g/L,亚甲基蓝浓度15mg/L,常温条件下,在60min左右,亚甲基蓝降解率达到了98%以上。结果表明,利用粉煤灰处理亚甲基蓝,具有处理效果好、简单,经济等特点。利用Freundlich等温式和Langmuir等温式对其吸附行为进行描述,表明粉煤灰易于吸附亚甲基蓝,吸附属于化学吸附;用颗粒内扩散方程和准二级吸附动力学方程对实验数据进行回归分析,更好地描述亚甲基蓝在粉煤灰上的吸附。准二级吸附动力学方程能够反映亚甲基蓝在粉煤灰上的吸附机理,准二级吸附速率常数k2=0.5758g/(mg.min)。本研究为粉煤灰处理印染废水提供了理论依据和实践依据。     

壳聚糖/膨润土复合材料的制备及对甲基橙的吸附性能

利用壳聚糖和膨润土,合成了具有良好吸附效果的天然高分子絮凝吸附材料。用傅里叶变换红外光谱仪表征了原料和产物的结构,通过改变吸附时间、温度、pH值和甲基橙溶液质量浓度等条件,考察了合成材料对甲基橙的吸附性能。结果表明,吸附剂用量为10g/L,温度20℃,溶液pH为4.70,吸附平衡30min后,甲基橙去除率达90%以上,其吸附过程符合Langmuir吸附模型,是放热过程。     

壳聚糖的吸附行为及其FTIR光谱研究

用自制的壳聚糖对几种酸性染料和碱性染料模拟废水进行了吸附行为的研究,考察了吸附时间、壳聚糖脱已酰度及废水pH值对吸附效果的影响。研究表明,在吸附开始的20 min内,壳聚糖对碱性品红和番红花红的吸附已基本达到平衡,且用量只为活性炭用量的2／3的情况下,对染料的吸附效果与活性炭几乎相当;它对酸性大红的吸附过程呈现一级反应动力学特征。文章还采用傅里叶变换红外光谱对壳聚糖吸附染料的机理进行了探讨,研究发现,壳聚糖分子中存在的大量羟基参与了对碱性品红和番红花红的吸附。     

Thermodynamic and kinetic parameters of ciprofloxacin adsorption onto modified coal fly ash from aqueous solution

Batch adsorption experiments were carried out for the removal of ciprofloxacin from aqueous solution using modified coal fly ash as adsorbent. The effects of various parameters such as contact time, initial solution concentration and temperature on the adsorption system were investigated. The optimum contact time was found to be 100 min. The isotherm adsorption data fit well with the Langmuir model, and the kinetic data fit well with the pseudo-second order and the intra-particle diffusion model. Intra-particle diffusion analysis demonstrates that ciprofloxacin diffuses quickly among the particles at the beginning of the adsorption process, and then the diffusion slows down and stabilizes. Thermodynamic parameters such as ΔG, ΔH and ΔS were also calculated. The negative Gibbs free energy change and the positive enthalpy change indicated the spontaneous and endothermic nature of the adsorption, and the positive entropy change indicated that the adsorption process was aided by increased randomness.     

原子吸收光谱法测定粉煤灰中氧化镁

采用火焰原子吸收光谱法测定粉煤灰中氧化镁的含量。用氢氟酸-高氯酸混合酸分解样品,以氯化锶消除其他元素的干扰。本方法操作简便、再现性好、灵敏度高,氧化镁浓度在0.10—2.00μg/mL之间线性关系良好,检出限可达0.02%,适用于粉煤灰中氧化镁的测定。     

Partitioning and transformation behavior of selenium during coal combustion

The partitioning of selenium in coal-fired flue gas and desulfurization wastewater is of great threat to the ecological environment and human health. However, the unclear understanding of interactions between selenium vapors and fly ash hinders the emission control of selenium from coal-fired power plants. To further illuminate the mechanism of selenium partitioning and transformation, this study carefully estimated selenium distribution characteristics in the coal combustion byproducts from several industrial power plants. The effective temperature range as well as the key ash components for selenium retention by fly ash was clarified by multiple-scale experiments and theoretical perspectives. The results showed that gaseous selenium tended to be captured by fly ash at a medium-to-low temperature range (i.e. below 650 °C). The limited residence time resulted in the incomplete capture of gaseous selenium by fly ash. Mullite, quartz, iron oxides, and anhydrite in fly ash were found to be the main trappers for gaseous selenium. Among these components, iron oxides showed excellent selenium adsorption performance at a wide temperature range of 150-700 °C, which was realized by the strong chemical adsorption. By contrast, as the dominant phases in fly ash for the physical adsorption of gaseous selenium, mullite and quartz mainly captured gaseous selenium below 300 °C. On the other hand, sulfur dioxides had priority over gaseous selenium to react with calcium-containing ash components by forming anhydrite in the high-temperature region. The formed anhydrite had a limited selenium adsorption capacity, which was confirmed to capture gaseous selenium through a combination of physical adsorption and weak chemical adsorption. For the in-depth control of selenium emitted into desulfurization system and atmosphere environment, these findings provided a comprehensive insight into the behavior of selenium partitioning and transformation into fly ash during coal combustion.     

Cr(VI) adsorption mechanism on rice husk ash burned at low temperature by method of IR spectra

Boehm titration method was used to analyze functional groups on cell surface of rice husk ash burned at low temperature in the present paper. Effects of initial pH value and temperature on Cr(VI) adsorption were studied, adsorption capacity was tested with the help of kinetic models and adsorption isotherms, instruments of Fourier transform infrared spectroscopy(FTIR) and scanning electron microscope (SEM) were used to check characteristics and adsorption mechanism of Cr(VI). The results indicated that optimal removing rate was achieved at initial pH value 5, and pH values of aqueous solution changed little be fore and after adsorption process. The adsorbent of rice husk ash could remove Cr(VI) effectively, and the maximum removing rate could be 95% with Cr(VI) concentration 20 mg x L(-1) and achieve 1-2 level of state standard(GB8978-1996). The adsorption process fits pseudo-second-order kinetic model and Langmuir isotherm better, the maximum adsorption capacity of Cr(VI) was 3.2776 mg x g(-1). Results of FTIR showed that amide II band, Si--O--Si, O--Si--O were important for Cr(VI) removal. SEM micrographs revealed that series of needle-shaped precipitation appeared on cell surface, and inorganic precipitation mechanism and redox mechanism might work in the test. As a kind of low cost adsorbent, rice husk ash can be applied to remove heavy metals in environment with great potential.     

Simultaneous adsorption of dyes and heavy metals from multicomponent solutions using fly ash

In wastewaters originating from dye industry there are amounts of dyes (very common methyl orange, methylene blue—MB) and heavy metals (cadmium, copper, nickel mainly from the organo-metallic dyes). They tend to adsorb in a competitive process and modify the substrate. Advanced removal is usually proposed via adsorption and the use of modified fly ash as a substrate is sustainable solution. The main constituents of fly ash (silica, alumina, iron oxide and un-burned carbon), are the priority compounds which favour the heavy metal adsorption and are active sites in dyes’ adsorption processes. The paper studies the effect of MB adsorbed on the fly ash surface on the removal efficiency of cadmium, copper and nickel ionic species from complex, multi-cationic dye solutions. The adsorption efficiency and kinetics are evaluated from the complex, multicomponent systems and possible influences are discussed. High efficiencies are obtained at low heavy metal concentrations (as it is the real case for the dyes industry) whereas at medium values, competitive processes lower the individual efficiencies of copper, nickel or cadmium from mixtures.     

新型复合固体除湿材料的吸附和解吸性能研究

为实现固体除湿系统吸附材料的低温再生及提高吸附材料的除湿效率,制备了新型复合固体除湿材料。新型复合固体除湿材料是以陶瓷纤维为基质,运用MgCl2浸渍改性硅胶及CaCl2二次强化方法而形成的复合物,复合固体除湿材料中MgCl2和CaCl2浓度均为25%。通过恒温恒湿空调室实验研究温度、风速、湿度对MgCl2/CaCl2改性复合材料除湿性能及再生特性。实验表明:在温度20℃、湿度70%条件下,复合固体除湿材料除湿量可达161 mg/g,是未改性除湿材料的3.2倍,是单一改性除湿材料的1.3倍;当系统平衡时,其除湿速率分别是未改性除湿材料的6.1倍,是单一改性除湿材料的2.6倍。除湿材料的平衡吸附量和吸附速率均与相对湿度成正比,与温度成反比;且风速在0.5 m/s条件时具有最大的除湿量。同时,在约70℃较低的脱附温度,8 min可脱附≥90%的总吸附水量,每1 g吸附剂可脱附水量高达145 mg;脱附再生6次后,除湿量依然较高为138 mg/g,且基本不再变化。     

Removal of fluoride in aqueous solution by adsorption on acid activated water treatment sludge

This paper reports the use of a pellet of adsorbent made from water treatment sludge (S) and acid activated water treatment sludge (SH) for removal of fluoride in the batch equilibration technique. The influence of pH, adsorbent dosage, temperature and effect of other ions were employed to find out the feasibility of acid activated adsorbent to remove fluoride to the permissible concentration of 0.7 mg/L. The results from the adsorption isotherm followed both Langmuir and Freundlich models and the highest fluoride removal was found for adsorbent activated with acetic acid at 2.0 mol/L. The optimum adsorbent dosage was found at 40 g/L, 0.01 mol/L acid activated adsorbent which was able to adsorb fluoride from 10 down to 0.11 mg/L. The adsorption capacity was decreased when the temperature increased. This revealed that the adsorption of fluoride on SH was exothermic. In the presence of nitrate and carbonate ions in the aqueous solution, fluoride removal efficiency of SH decreased from 94.4% to 86.6% and 90.8%, respectively. However, there is no significant effect in the presence of sulfate and chloride ions.