Synthesis of highly fluorescent and water soluble graphene quantum dots for detection of heavy metal ions in aqueous media

Environmental Science and Pollution Research - Fluorescent graphene quantum dots (GQDs) are nanomaterials which possess unique properties that show great potential in different applications. In...     

N-doped carbon fibers in situ prepared by hydrothermal carbonization of Camellia sinensis branches waste for efficient removal of heavy metal ions

Environmental Science and Pollution Research - N-doped carbon fibers (NCFs) were in situ prepared by Camellia sinensis branches waste through hydrothermal carbonization with urea/ZnCl2 at...     

Removal of heavy metal ions from wastewaters using dendrimer-functionalized multi-walled carbon nanotubes

Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb²⁺, Hg²⁺, and Ni²⁺ and the harmless Ca²⁺ ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 μg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg²⁺ ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery.     

橘子皮皂化改性及其对重金属离子的吸附

以农林废弃物橘子皮(OP)为原料,经氢氧化钠皂化处理,得到了改性橘子皮生物吸附剂(MOP),并将其用于对水溶液中重金属离子的吸附.研究了氢氧化钠溶液浓度、浸泡时间对改性产物产率和吸附性能的影响;通过扫描电镜、红外光谱分析,化学耗氧量、比表面积、Zeta电位的测定等方法研究了橘子皮皂化改性的机理.结果表明,橘子皮用0.2...     

4种重金属离子对间接火焰原子吸收光谱法测定铝的干扰

空气-乙炔间接火焰原子吸收法是我国目前运用较多且易于推广的铝检测方法,研究了Mg2+、Ca2+、Zn2+和Ni2+4种离子对此法测定0.40 mg/L Al3+ 的干扰情况。得出如下结论:(1)在±5% 误差范围内,15.10 mg/L Mg2+、105.00 mg/L Ca2+、0.23 mg/L Zn2+、0.88 mg/L Ni2+对0.40 mg/L Al3+ 无干扰。(2)本方法虽然操作复杂,但成本较低、灵敏度高,检测的浓度范围宽、稳定性好,加标回收率为96%~99%,检出限为0.04 mg/L,适宜测定范围为0.05~100.00 mg/L,适用于饮用水、河水及地下水中Al3+ 的测定。     

重金属离子在钠基膨润土中的吸附特征与机理

膨润土是一种天然粘土矿物,比表面积大、吸附能力强。通过钠基膨润土对复合重金属离子Cu2+、Zn2+和Cd2+的竞争吸附实验研究,探讨了钠基膨润土对Cu2+、Zn2+和Cd2+的吸附特征。结果表明,钠基膨润土对Cu2+、Zn2+和Cd2+的吸附随离子浓度增加而增大。吸附具有选择性,Cu2+、Zn2+和Cd2+的吸附能力大小顺序为Cu2+>Zn2+>Cd2+。并通过XRD及IR等分析探讨了钠基膨润土的吸附机理主要表现为离子交换吸附。     

廉价吸附剂处理重金属离子废水的研究进展

随着现代工业的迅速发展,生产过程中排出的有害重金属离子废水日益增加.寻找较为廉价的废水净化材料,对其中有害重金属离子的有效处理已成为环境保护中亟待解决的问题.廉价吸附剂的使用取代了目前成本较高的从溶液中回收重金属离子的方法,同时吸附剂改性会大大提高其吸附量.阐述了壳聚糖、海泡石、膨润土、海藻和泥炭等结构组成、吸附和离子交换性能等,报道廉价吸附剂对一些重金属离子的最大吸附量是:796 mg Pb/g壳聚糖,1123 mg Hg/g壳聚糖,92 mg Cr(Ⅲ)/g壳聚糖,76 mg Cr(Ⅲ)/g泥炭,41 mg Pb/g膨润土,558 mg Cd/g壳聚糖,215 mg Cd/g海藻.由此展现了廉价吸附剂在重金属离子废水处理过程中的巨大优势和良好的发展前景.     

廉价吸附剂处理重金属离子废水的研究进展

随着现代工业的迅速发展，生产过程中排出的有害重金属离子废水日益增加。寻找较为廉价的废水净化材料，对其中有害重金属离子的有效处理已成为环境保护中亟待解决的问题。廉价吸附剂的使用取代了目前成本较高的从溶液中回收重金属离子的方法，同时吸附剂改性会大大提高其吸附量。阐述了壳聚糖、海泡石、膨润土、海藻和泥炭等结构组成、吸附和离子交换性能等，报道廉价吸附剂对一些重金属离子的最大吸附量是：796mgPb／g壳聚糖，1123mgHg／g壳聚糖。92mgcr（Ⅲ）／g壳聚糖，76mgCr（Ⅲ）／g泥炭，41mgPb／g膨润土，558mgCd／g壳聚糖，215mgCd／g海藻。由此展现了廉价吸附剂在重金属离子废水处理过程中的巨大优势和良好的发展前景。     

橘子皮皂化交联改性及其对重金属离子的吸附

以生物废料橘子皮(OP)为原料,经乙醇、NaOH和CaCl2处理,得到皂化交联改性橘子皮(SCOP)生物吸附剂,将其用于对重金属离子Cu2+、pb2+、Cd2+、Zn2+和Ni2+的吸附,并研究了溶液pH、吸附时间和重金属离子初始浓度对SCOP吸附性能的影响.结果表明,重金属离子在改性橘子皮上的吸附速率快,符合准二级动力学方程;改性橘子皮对Cu2+、pb2+、Zn2+和Ni2+的吸附等温线符合Langmuir方程,对Cd2+的吸附等温线符合Freundlich方程,根据Langmuir方程计算对Cu2+、pb2+、Cd2+、Zn2+和Ni2+的饱和吸附量分别为72.73、209.80、85.84、56.18、33.80mg/g,均高于改性前.改性后的橘子皮生物吸附剂可以再生重复使用4次以上,是性能良好的重金属离子吸附剂.     

胺基树脂的合成及对水中重金属离子的吸附特征

研究了使用氯甲基化聚苯乙烯交联微球为前驱体与二乙烯三胺经回流反应合成胺基树脂及其对水中Cd2+和Ni2+的吸附特征。结果表明,胺基官能团成功地嫁接到树脂表面,胺基含量为5.6 mmol/g。胺基树脂对Cd2+和Ni2+的吸附等温线表明,温度的升高有利于吸附,且吸附等温线都符合Langmuir模型。pH值对吸附的影响较大,最佳吸附pH值范围为4~6。2种金属离子在胺基树脂上的吸附都符合准二级动力学方程。     

饱和膨润土复合颗粒吸附剂吸附的重金属离子的固定及其再生

采用Na_2S化学再生法对吸附Fe~(2+)、Mn~(2+)、Cu~(2+)和Zn~(2+)饱和的膨润土-钢渣复合颗粒吸附剂分别进行重金属离子的固定及其再生实验研究,探究该吸附剂吸附的重金属离子的固定问题及其再生的可能性和多次再生后的吸附效果,同时根据SEM图进一步揭示固定、再生机理。结果表明:在对Fe~(2+)的固定、再生实验中,可形成Fe S沉淀而实现固定,但再生后再吸附时,膨润土复合颗粒中蒙脱石结构改变使得颗粒坍塌变成粉末状,因此,吸附Fe~(2+)饱和的膨润土复合颗粒吸附剂不适合用Na_2S再生;而对Mn~(2+)、Cu~(2+)和Zn~(2+)的固定、再生实验中,均可形成S化物沉淀而实现固定,颗粒结构未改变,经过3次再生后,吸附剂对Mn~(2+)、Cu~(2+)和Zn~(2+)的去除率还可达到94.22%、83.2%和76.30%,远比未经再生的吸附剂吸附效果好,同时,由SEM表征分析进一步揭示:Na_2S再生溶液既可使重金属离子形成MS沉淀固定,又可使复合颗粒吸附剂获得再生,实现了同步固定、再生的目的,且吸附剂经多次再生后吸附效果保持良好。     

介孔(TiO2-M)/导电碳毡光电极制备及其光电催化性能

以表面活性剂十六烷基三甲基溴化铵、四氯化钛和金属离子分别为造孔模板、钛源和掺杂剂,通过水热法合成金属离子掺杂介孔二氧化钛（MPT-M）负载导电碳毡（CCF）复合材料（（MPT-M）/CCF）。利用X-射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、傅里叶红外（FT-IR）、N2吸附-脱附和热重-差热（TG-DTA）等对样品结构进行表征。以气相苯甲醛为目标降解物,探讨了合成材料在紫外光和可见光下的催化性能。结果表明,金属离子Pt的掺杂降低了（MPT-Pt）/CCF的粒径,提高了比表面积和羟基浓度,使得（MPT-Pt）/CCF的光催化活性明显高于其他3种样品（（MPT-Mn）/CCF、（MPT-Fe）/CCF、（MPT-Zn）/CCF）,并且具有较好的重复使用性能。最佳的光电催化降解条件为温度35℃、相对湿度55%、偏电压为10 V、初始浓度如40 mg·m-3。     

Pre-concentration and separation of heavy metal ions by chemically modified waste paper gel

Iminodiacetic acid was immobilized on waste paper by chemical modification in order to develop a new type of adsorption gel for heavy metal ions. Adsorption behavior of the gel was investigated for a number of metal ions, specifically Cu(II), Pb(II), Fe(III), Ni(II), Cd(II), and Co(II) at acidic pH. From batch adsorption tests, the order of selectivity was found to be as follows: Cu(II)  Fe(III) > Pb(II) > Ni(II)  Co(II) > Cd(II). Column tests were carried out for pairs of metal ions to understand the separation and pre-concentration behavior of the gel. It was found that mutual separation of Ni(II) from Co(II) and that of Pb(II) from Cd(II) can be achieved at pH 3. Similarly, selective separation of Cu(II) from Cu(II)–Fe(III) and Cu(II)–Pb(II) mixtures at pH 1.5 and 2, respectively, was observed by using this new adsorption gel. In all cases, almost complete recovery of the adsorbed metal was confirmed by elution tests with HCl.     

一步法低温合成二维CNx纳米材料及其对水中重金属离子的吸附性能

利用尿素和乙二胺四乙酸钠盐通过一步法低温固相裂解合成了二维纳米碳氮材料(2-D CN_x),实现了对水中重金属离子的吸附去除。系统地研究了2-D CN_x对水中重金属离子Cd~(2+)、Pb~(2+)和Cu~(2+)的吸附性能,其吸附动力学过程均符合准二级动力学模型,吸附等温线更符合Langmuir模型。结果表明:Cd~(2+)、Cu~(2+)和Pb~(2+)的初始浓度均为40 mg·L~(-1),在25℃下,达到平衡时吸附量分别达到了79.4、 58.5、 72.8 mg·g~(-1); 2-D CN_x在比较广泛的pH范围(3.0～9.0)内对重金属离子都具有比较好的吸附效果;吸附剂在吸附柱过滤穿透实验中表现出很好的吸附效果和可重复利用性,且具有良好的机械稳定性。进一步的机理分析探明,吸附主要基于材料表面的羟基和重金属离子交换及氨基与重金属离子的络合协同作用。     

壳聚糖联合碱改性粉煤灰对重金属离子的吸附特性

采用浸渍法将壳聚糖负载在经NaOH改性的粉煤灰上,制备了联合改性的粉煤灰。随粉煤灰上壳聚糖负载量的增加,粉煤灰对Pb2+和Cd2+的吸附率均提高。当负载壳聚糖的质量分数为8%,吸附温度为30℃,吸附时间为120 min时,粉煤灰对Pb2+的吸附率最高（为98.9%）,对Cd2+的吸附率也最高（为91.5%）。其吸附行为符合Freundlich等温吸附模型,但表现为2个线性区。粉煤灰负载壳聚糖的改性机理是粉煤灰与带正电荷的壳聚糖的化学键合作用。     

Removal of bisphenol A and some heavy metal ions by polydivinylbenzene magnetic latex particles

In this study, magnetic polydivinylbenzene latex particles MP_DVB with a core-shell structure were tested for the removal of bisphenol A (BPA), copper Cu(II), lead Pb(II), and zinc Zn(II) from aqueous solutions by a batch-adsorption technique. The effect of different parameters, such as initial concentration of pollutant, contact time, adsorbent dose, and initial pH solution on the adsorption of the different adsorbates considered was investigated. The adsorption of BPA, Cu(II), Pb(II), and Zn(II) was found to be fast, and the equilibrium was achieved within 30 min. The pH 5–5.5 was found to be the most suitable pH for metal removal. The presence of electrolytes and their increasing concentration reduced the metal adsorption capacity of the adsorbent. Whereas, the optimal pH for BPA adsorption was found 7, both hydrogen bonds and π–π interaction were thought responsible for the adsorption of BPA on MP_DVB. The adsorption kinetics of BPA, Cu(II), Pb(II), and Zn(II) were found to follow a pseudo-second-order kinetic model. Equilibrium data for BPA, Cu(II), Pb(II), and Zn(II) adsorption were fitted well by the Langmuir isotherm model. Furthermore, the desorption and regeneration studies have proven that MP_DVB can be employed repeatedly without impacting its adsorption capacity.     

Selective removal of the heavy metal ions from waters and industrial wastewaters by ion-exchange method

By ion exchange undesirable ions are replaced by others which don't contribute to contamination of the environment. The method is technologically simple and enables efficient removal of even traces of impurities from solutions. Examples of selective removal of heavy metal ions by ion-exchange are presented. They include removal of Pb(II), Hg(II), Cd(II), Ni(II), V(IV,V), Cr(III,VI), Cu(II) and Zn(II) from water and industrial wastewaters by means various modern types of ion exchangers.     

Facile synthesis of cadmium-doped graphite carbon nitride for photocatalytic degradation of tetracycline under visible light irradiation

In recent years, using semiconductor photocatalysts for antibiotic contaminant degradation under visible light has become a hot topic. Herein, a novel and ingenious cadmium-doped graphite phase carbon nitride (Cd-g-C₃N₄) photocatalyst was successfully constructed via the thermal polymerization method. Experimental and characterization results revealed that cadmium (Cd) was well doped at the g-C₃N₄ surface and exhibited high intercontact with g-C₃N₄. Additionally, the introduction of cadmium significantly improved the photocatalytic activity, and the optimum degradation efficiency of tetracycline (TC) reached 98.1%, which was exceeded 2.0 times that of g-C₃N₄ (43.9%). Meanwhile, the Cd-doped sample presented a higher efficiency of electrical conductivity, light absorption property, and photogenerated electron-hole pair migration compared with g-C₃N₄. Additionally, the quenching experiments and electron spin-resonance tests exhibited that holes (h⁺), hydroxyl radicals (?OH), superoxide radicals (?O₂^?) were the main active species involved in TC degradation. The effects of various conditions on photocatalytic degradation, such as pH, initial TC concentrations, and catalyst dosage, were also researched. Finally, the degradation mechanism was elaborated in detail. This work gives a reasonable point to synthesizing high-efficiency and economic metal-doped photocatalysts.

     

复合纳米材料对土壤重金属离子吸持固化的模拟研究

土壤中过量重金属离子可通过食物链和地表水系统危害人群健康。通过土柱淋溶模拟实验,研究了SiO2-Al2O3-Fe2O3等复合纳米材料对土壤溶液中Cu2+、Cd2+、Pb2+、Zn2+和Ni2+的吸持与固化特征。分别向重金属含量4倍于土壤二级标准(GB15618-1995)的土壤中添加0%、4%、6%和10%的复合纳米材料,分析不同深度土壤渗滤液以及土柱上栽培植物不同部位中重金属的含量。结果表明,碱性壤质土壤中重金属向下的迁移量很少;在含4%复合纳米材料土柱中,其吸持固化土壤溶液中63%的Cu、79%的Cd、68%的Pb、89%的Zn和76%的Ni;在含6%复合纳米材料土柱中,其吸持固化土壤溶液中82%的Cu、92%的Cd、76%的Pb、91%的Zn和88%的Ni;再增加土柱中复合纳米材料的含量,其吸持固化效果并不再显著增加。     

Carbon nanotubes from waste cooking palm oil as adsorbent materials for the adsorption of heavy metal ions

Environmental Science and Pollution Research - In this work, waste cooking palm oil (WCPO)-based carbon nanotubes (CNTs) with encapsulated iron (Fe) nanoparticles have been successfully produced...