Preparation and characterization of calcium alginate-based composite adsorbents for the removal of Cd,Hg, and Pb ions from aqueous solution

Composite adsorbent materials containing calcium alginate, clinoptilolite, and coal-derived humic acid were prepared. Humic acid (HA), clinoptilolite (CL), alginate (AL), alginate-entrapped humic acid (AL/HA), clinoptilolite (AL/CL), and humic acid/clinoptilolite (AL/HA/CL) samples were characterized. The effectiveness of the samples as adsorbents for the removal of cadmium (Cd), mercury (Hg), and lead (Pb) were studied in a series of batch-adsorption experiments. For the AL, AL/HA, AL/CL, and AL/HA/CL adsorbents, uptake versus time data were evaluated using two kinetic models, a linear and a non-linear pseudo-first-order and a pseudo-second-order model. The data for each metal ion on all adsorbents showed good correspondence with the pseudo-second-order kinetic model. The equilibrium data were fitted to Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models. The results show that a non-linear method seems more appropriate for obtaining isotherm parameters. The non-linear Freundlich and Langmuir models for Pb and Hg produced a best fit with high R ² value (0.99). For HA adsorbent, the equilibrium data for Cd removal better fit to the non-linear Dubinin–Radushkevich isotherm.     

Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Abstract

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm^?2 day^?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm^?2 day^?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Amelioration of fluoride toxicity by vitamins and calcium on reproductive organs of female rat

Normal female rats of Wistar strain (Rattus norvegicus) weighing between 150–200 g were treated with fluoride (Fl) contaminated drinking water (FW, 5.8 ppm), vitamin C (6 mg) and vitamin C (6 mg) + D (6 mg once a week) + calcium (6 mg) for 30 days. Fl water treatment to rats produced reduction in weights of ovaries, uterus, vagina, kidneys, and adrenal glands, circulating levels of estrogen, number of litters, fertility rate, and altered tissue and serum biochemistry compared to control rats. However, cholesterol concentrations of ovaries and adrenals increased significantly. The above altered parameters were restored partially/completely after exogenous feeding with vitamin C and vitamins (C + D) and calcium. The data suggest that Fl-induced adverse effects on reproductive and other organs in female rats, whereas vitamin C, vitamin D and calcium treatment ameliorated Fl toxicity. Therefore, vitamins (C and D) and calcium play an important role in prophylactic treatment of fluorosis.     

Effects of a phycotoxin,okadaic acid,on oyster heart cell survival

Okadaic acid (OA) is a dinoflagellate toxin which accumulates in shellfish producing diarrhetic shellfish poisoning (DSP) in humans. It was found that OA is a highly selective inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A) which produces a marked increase in phosphorylation of several proteins, including p38 mitogen-activated protein (MAP) kinase. The cytotoxicity attributed to OA and the effects on p38 MAP kinase and calcium current were examined in the oyster Crassostrea gigas in this study. Data showed that p38 MAP kinase is strongly expressed in oyster heart and that OA bioaccumulated in cultured heart cells. Hence the effects of OA was tested in vitro and in vivo on oysters. OA was found to (i) exert a positive chronotropic effect on cultured atrial cardiomyocytes which is related to an increase in calcium current via PKC as shown by patch clamp measurements, (ii) produce an activation/phosphorylation of MAP kinase as shown by Westernblot while the non-phosphorylated p38 remained constant during treatment, (iii) did not induce a pro-apoptotic effect. Data suggest that OA may also stimulate the anti-apoptotic pathway by phosphatase inhibition.     

两性高分子螯合絮凝剂和氯化钙对羟基亚乙基二膦酸预镀铜废水的去除性能

以羟基亚乙基二膦酸(HEDP)预镀铜废水为处理对象,考察两性高分子螯合絮凝剂(ACPF)和CaCl2对其处理效果.结果表明,单独使用ACPF或CaCl2,用量大,残余Cu2+和COD浓度均不能达到电镀污染物排放标准(GB21900—2008);将ACPF和CaCl2配合使用,Ca2+可与HEDP螯合生成HEDP—Ca沉淀,促进ACPF与Cu2+螯合;且Ca2+还可与废水中的酒石酸根离子形成溶解度很小的结晶,促进絮体的形成和沉降.因此,处理药剂的用量明显降低,Cu2+和COD残余浓度均能达标.适宜的处理条件为:弱碱或碱性条件下,ACPF投加量为3.0 g.L-1,CaCl2投加量为2.0 g.L-1,Cu2+和COD的去除率分别达99.74%和97.5%,残余浓度分别为0.335和25.27 mg.L-1.     

Preparation and application of a phosphorous free and non-nitrogen scale inhibitor in industrial cooling water systems

A novel environmentally friendly type of calcium carbonate, zinc (II) and iron (III) scale inhibitor Acrylic acid- allylpolyethoxy carboxylate copolymer (AA-APEL) was synthesized. The anti-scale property of the AA-APEL toward CaCO₃, zinc (II) and iron (III) in the artificial cooling water was studied through static scale inhibition tests. The observation shows that both calcium carbonate, zinc (II) and iron (III) inhibition increase with increasing the dosage of AA-APEL. The effect on formation of CaCO₃ was investigated with combination of scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) analysis and fourier transform infrared spectrometer, respectively. The results showed that the AA-APEL copolymer not only influenced calcium carbonate crystal morphology and crystal size but also the crystallinity. The crystallization of CaCO₃ in the absence of inhibitor was rhombohedral calcite crystal, whereas a mixture of calcite with vaterite crystals was found in the presence of the AA-APEL copolymer. Inhibition mechanism is proposed that the interactions between calcium or iron ions and polyethylene glycol (PEG) are the fundamental impetus to restrain the formation of the scale in cooling water systems.     

模拟降雨条件下料浆石对土壤水分入渗的影响

论文基于田间坡地人工模拟降雨实验,分析了料浆石覆盖及嵌入对入渗过程的影响,对比了其入渗速率及拟合参数的变化趋势。其结果表明,随料浆石覆盖度及料浆石嵌入含量的增加,入渗补给系数逐渐减小,且后者对其影响显著;料浆石嵌入小区的平均入渗速率及稳定入渗速率随料浆石含量的增加而缓慢减小。Kostiakov入渗经验公式和Philip方程均可以对降雨入渗过程进行描述。     

不同氧化法对模拟聚合物驱废水降黏效果的影响

分别采用UV-Fenton试剂氧化法、次氯酸钙氧化法和二氧化氯氧化法处理模拟聚合物驱废水,考察了各工艺条件对废水降黏效果的影响。实验结果表明:在初始废水pH为7、反应温度为50℃、反应时间为20 min的条件下,UV-Fenton试剂氧化法适宜的H2O2加入量为1 mmol/L,n(H2O2)∶n(Fe2+)=10,处理后废水降黏率达65.7%;次氯酸钙氧化法适宜的次氯酸钙加入量为500 mg/L,处理后废水降黏率达81.7%;二氧化氯氧化法适宜的二氧化氯加入量为100 mg/L,处理后废水降黏率为40.9%。3种氧化法对模拟聚合物驱废水的降黏率大小顺序为:次氯酸钙氧化法>UV-Fenton试剂氧化法>二氧化氯氧化法。     

2×600MW机组脱硫石膏亚硫酸钙含量超标原因分析及对策

石灰石—石膏湿法脱硫系统工艺复杂,影响石膏中亚硫酸钙含量的因素很多,各因素之间又相互作用。分析了某电厂2×600MW机组脱硫石膏亚硫酸钙含量超标的原因,在试验研究及系统改造的基础上指出了石灰石原料不合格是石膏品质变差的主要原因。应加强石灰石原料质量监督,以满足脱硫系统要求。     

次氯酸钙法处理发泡剂生产废水

采用废漂白液(次氯酸钙)处理发泡剂偶氮二甲酰胺生产废水。废水pH为8～9时,加入质量分数3％～5％的漂白液和1‰PAM絮凝剂,反应2h,沉淀澄清。实验室试验中COD去除率为88％,工业处理试验中COD平均由626mg／L降为105mg／L,去除率为83．2％。该法工艺简单,以废治废,费用低,处理效果好。