CN101830539A - 不溶性组合物 - Google Patents

不溶性组合物 Download PDF

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CN101830539A
CN101830539A CN201010143178A CN201010143178A CN101830539A CN 101830539 A CN101830539 A CN 101830539A CN 201010143178 A CN201010143178 A CN 201010143178A CN 201010143178 A CN201010143178 A CN 201010143178A CN 101830539 A CN101830539 A CN 101830539A
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rare earth
water
compound
oxo
anions
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E·B·麦科纽
R·D·威特汉姆
J·L·伯尔巴三世
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Chevron Mining Inc
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Abstract

本申请公开了一种不溶性组合物，包括：稀土化合物和含氧阴离子，所述含氧阴离子具有选自5、13、14、22-25、31、32、40-42、44、45、49-52、72-75、77、78、82、83和92的原子序数的元素。

Description

不溶性组合物
本申请是申请日为2006年7月26日、申请号为200680034885.0、发明名称为“使用稀土从含水料流中除去含氧阴离子的方法”的申请的分案申请。
发明背景
本发明通常涉及从含水料流中除去有毒物质例如重金属和它们的放射性同位素的含氧阴离子的方法和设备，并特别涉及使用稀土化合物从地下水、废水和饮用水中除去这些有毒物质的方法。
有毒金属和它们的放射性同位素相当频繁地从地球化学反应、工业废物排放(包括由核电站所产生的那些)、过去含有有毒金属的杀虫剂在农业中的使用和其它源头进入地下水。在靠近矿区的涌出水中，经常发现放射性物质和有毒金属的组合。环境法规经常要求将这些有毒物质除至极低的水平。
过去，已经使用了各种工艺以从含水体系中除去金属。这些工艺的实例包括在高表面积材料例如氧化铝和活性炭上吸附、与阴离子交换树脂进行离子交换、使用絮凝剂进行共沉淀、和进行电渗析。然而，大多数用来除金属的工艺对于除去大多数这些金属和/或它们的放射性同位素来说不是普遍有效的。而且，由于空间要求和需要使用危险的化学品，已经在大型市政供水中使用的用来除去重金属以生产饮用水的工艺通常不适用于住宅应用。
因此，需要新型工艺以从体积巨大的饮用水、井水和工业水中经济而有效地除去多种不同类型的有毒金属。此外，需要这些工艺能够从这些含水料流中除去各种放射性物质，或者单独除去，或者与有毒的非放射性金属一起除去。
发明概述
根据本发明，现已发现，通常处于一价和/或多价的含氧阴离子的形式的有毒金属和/或放射性元素，可从水和其它含水原料中方便而有效地除去，方法是用稀土化合物或稀土化合物的混合物处理含有这些污染物的含水原料。在本发明的一个实施方案中，受污染的含水原料与固体吸收剂接触以生产这些污染物浓度有所减少的含水液体，所述固体吸收剂包含稀土化合物或稀土化合物的混合物，例如氧化镧、二氧化铈或它们的混合物。尽管所述固体吸收剂可基本上由纯稀土化合物或纯稀土化合物的混合物组成，所述稀土或稀土的混合物通常负载在颗粒状固体上或与颗粒状固体混合。所述吸收剂中的稀土化合物与含水原料中的所述金属、放射性同位素或其它有毒元素的含氧阴离子反应以生成不溶物质，所述不溶物质通过吸附、吸收或既吸附又吸收而固定化在所述不溶的吸收剂颗粒中，从而得到基本上净化的含水料流。
如果所述吸收剂含有负载有一种或多种稀土化合物的颗粒状固体或与一种或多种稀土化合物混合的颗粒状固体，所述颗粒状固体通常，但不总是，具有相当小的对稀土的离子交换能力，通常小于20毫当量每100克。所述颗粒状固体可以是氧化铝、硅藻土、多孔聚合材料、耐火氧化物或非氧化物耐火材料。所述颗粒状固体还可以是粘土，尤其是对稀土的离子交换能力小于20毫当量每100克的粘土。
在本发明的另一个实施方案中，用一种或多种可溶的稀土化合物的水溶液代替固体稀土吸收剂来处理含有污染物含氧阴离子的含水原料。将该稀土水溶液注入所述含水原料中，在那里可溶的稀土化合物与污染物含氧阴离子发生反应以将它们从原料中沉淀出来，从而产生这些污染物的浓度有所降低的含水液体。
在本发明的方法的优选的实施方案中，使含有一种或多种元素的含氧阴离子的含水液体与吸收剂接触，其中所述元素选自铋、钒、铬、锰、钼、锑、钨、铅、铪和铀，所述吸收剂包含负载在颗粒状氧化铝或硅藻土上的二氧化铈或二氧化铈和氧化镧的组合。所述稀土与所述含氧阴离子发生反应以生成吸附在所述颗粒状吸收剂上的不溶化合物，并从而产生污染物含氧阴离子耗尽的含水流出物。
发明详述
尽管本发明的方法主要是设计用于从饮用水和地下水中除去各种金属和/或放射性物质，所述金属和/或放射性物质通常以所述污染物元素的单价和/或多价含氧阴离子的形式存在，可以理解的是，本方法可用于处理含有不希望的量的这些污染物的任何含水液体原料。这类液体原料的实例包括，例如，井水；地表水例如河水、湖水、池塘水和沼泽水；农业用水、工业工艺废水和地热流体。
由本发明的方法有效处理的含水原料可含有一种或多种大序数的污染物金属、非金属和/或放射性同位素，它们以这些污染物元素的含氧阴离子形式存在。在所述原料中可发现的金属或非金属污染物的实例包括原子序数为5、13、14、22-25、31、32、40-42、44、45、49-52、72-75、77、78、82和83的元素的含氧阴离子。这些元素包括硼、铝、硅、钛、钒、铬、锰、镓、锗、锆、铌、钼、钌、铑、铟、锡、锑、碲、铪、钽、钨、铼、铱、铂、铅和铋。原子序数为92的铀是可存在于所述原料中的放射性污染物的实例。出于本发明的目的，含氧阴离子包括含有与一种或多种其它元素结合的氧的任何阴离子。
在本发明的方法的一个优选的实施方案中，被一种或多种以上所述的含氧阴离子污染的含水原料在使原料中的水保持液态的温度和压力(通常为环境条件)下穿过入口进入吸收容器。如果原料被颗粒状固体所污染，通常在它进入吸收容器之前对其进行处理以除去这些固体。任何液-固分离技术，例如过滤、离心分离和水力旋流分离，可用于除去这些颗粒状固体。通常，所述吸收容器含有所述吸收剂的填充床，受污染的原料穿过该填充床向下运动。然而，如果希望，所述受污染的原料可以穿过膨胀的或流态化的吸收剂床层向上运动。
在该吸收容器中，所述含水原料与包含一种或多种稀土化合物的固体吸收剂接触。通常，该吸收剂优选含有镧化合物(优选氧化镧)、铈化合物(优选二氧化铈或水合铈氧化物)或镧化合物和铈化合物的混合物。然而，所述吸收剂可含有其它稀土的化合物，包括镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇和钪的化合物。尽管通常优选这些稀土的氧化物，可使用其它不溶于水的稀土化合物，包括稀土的水合氧化物、稀土的碳酸盐、稀土的磷酸盐、稀土的氟化物等，但不包括稀土的硅酸盐。
所述固体吸收剂可基本上由稀土化合物或稀土化合物的混合物组成，或所述固体吸收剂可包含或者与颗粒状固体混合的或者负载于颗粒状固体基质上的一种或多种稀土化合物。如此前所提到的，如果一种或多种稀土化合物与颗粒状固体混合或者负载于颗粒状固体之上，这些固体对所述一种或多种稀土化合物的阳离子交换能力将小于20毫当量每100克。所述颗粒状固体还将是不溶于水的，其表面积为约5-1000m2/g，通常为约80-800m2/g，和其颗粒尺寸为约2-约1200微米，通常为约20-约1000微米。这类固体的实例包括金属氧化物，例如氧化铝、二氧化硅和二氧化钛；非氧化物耐火材料，例如氮化钛、氮化硅和碳化硅；硅藻土；莫莱石；多孔聚合材料，例如粗网眼的颗粒；多孔碳；和纤维材料。通常优选所述一种或多种稀土化合物与氧化铝或硅藻土混合或负载于氧化铝或硅藻土之上。
某些类型的粘土也可用作所述颗粒状固体，优选对所述一种或多种稀土化合物的阳离子交换能力小于20毫当量每100克的粘土。这类粘土的实例包括绿泥石、埃洛石和高岭土。如果这些粘土用作所述一种或多种稀土化合物的基质且这些化合物在水中溶解度低，没有显著的交换到这些粘土上的离子。因此，所述粘土严格地充作载体。
在吸收容器中，所述含水原料或者与包含所述吸收剂的不溶于水的颗粒状固体成浆，或者穿过所述吸收剂颗粒的固定床或膨胀床。如果所述吸收剂包含与颗粒状固体混合的一种或多种稀土化合物，所述混合物通常含有约5.0-95wt％的煅烧成氧化物的所述一种或多种稀土化合物。优选地，所述混合物将含有约10-50wt％的、更优选约20-30wt％的煅烧成氧化物的所述一种或多种稀土化合物。
无论所述一种或多种稀土化合物是以与颗粒状固体的混合物的形式还是以负载在颗粒状固体上的形式存在于所述吸收容器中，吸收容器中的所述固体的直径通常为约2-1200微米。当所述一种或多种稀土化合物和所述颗粒状固体作为固定床存在于吸收容器中时，通常优选所述颗粒为球形以使穿过该床层的含水原料的流动均匀分布。然而，如果希望，所述颗粒可以采用其它形状，包括挤出物的形状。
随着含水原料穿过吸收容器，含水原料中的含氧阴离子与稀土化合物表面上的稀土阳离子例如La3+和Ce4+接触并发生反应，生成不溶的稀土含氧阴离子化合物，该不溶的稀土含氧阴离子化合物保留在吸收容器中，吸附和/或吸收在所述稀土化合物和颗粒状固体(如果存在的话)上。这类反应的实例通过如下方程式举例说明：
Ce4+(CeO2)+含氧阴离子4-->Ce含氧阴离子(沉淀)
La3+(La2O3)+含氧阴离子3-->La含氧阴离子(沉淀)
在含水原料中可发现的常见含氧阴离子的实例包括CrO4 2-、WO4 2-、MoO4 2-、SbO3 -、MnO4 2-、UO4 2-和VO4 3-。在吸收容器中由这些含氧阴离子生成的相应的不溶的镧和铈含氧阴离子化合物包括，例如，铬酸镧[La2(CrO4)3]、铬酸铈[Ce(CrO4)2]、钨酸镧[La2(WO4)3]、钨酸铈[Ce(WO4)2]、钼酸镧[La2(MoO4)3]、钼酸铈[Ce(MoO4)2]、锑酸镧[La(SbO3)3]、锑酸铈[Ce(SbO3)4]、锰酸镧[La2(MnO4)3]、铀酸镧[La2(UO4)3]、铀酸铈[Ce(UO4)2]和钒酸镧[LaVO4]。
在某些情况下，所述受污染的含水原料可含有处于这样氧化态的金属，该氧化态使它们的含氧阴离子难以生成，所以根据本发明不可能从水中除去这样氧化态的金属。例如，处于+3氧化态的铬，它是非致癌的，它难以从水中除去并倾向于转化成被EPA列为致癌物的处于+6氧化态的铬的含氧阴离子。氧化态为+4的铈和镨，Ce4+和Pr4 +，是非常强的氧化剂，能够将氧化态为+3的铬氧化为氧化态为+6的铬，后者在水中主要以CrO4 2-和/或Cr2O7 2-含氧阴离子形式存在。在这个氧化反应过程中，Ce4+和Pr4+阳离子被还原为Ce3+和Pr3+阳离子，Ce3+和Pr3+阳离子易于与铬含氧阴离子反应生成不溶性沉淀。因此，在某些情况下，在吸收剂中使用含有氧化态为+4的稀土元素的稀土化合物，例如CeO2和PrO2，是有利的。
所述吸收容器通常保持在约1-约100℃的温度下，优选保持在环境温度下。当所述吸收剂在吸收容器中作为固定床或填充床而存在时，所沉淀的稀土含氧阴离子化合物将被吸收剂的固体颗粒所吸附或以其它方式与吸收剂的固体颗粒结合，使得离开所述吸收容器的含水流体将基本上不含有固体和含有非常少量的含氧阴离子。如果吸收剂与含水原料在吸收容器中成浆，通常对该容器的流出物进行处理以将所述颗粒状吸收剂颗粒包括在该容器中生成的不溶的稀土含氧阴离子化合物与含氧阴离子耗尽的液体分离开。尽管可在任何类型的能够从液体中除去颗粒的设备中进行所述分离，通常采用过滤系统。
在本发明的方法的优选的实施方案中，使用含有药筒、过滤器或介质柱的净化设备作为吸收容器来处理含有污染物含氧阴离子的住宅饮用水。该处理设备可以是自由固定的水箱，其具有含有稀土吸收剂的过滤设备，或者在水槽下面设计安装药筒型的设备。安装这些设备以使得进入家庭或商业场所的水在进入水槽的水龙头之前穿过所述过滤器或药筒。所述过滤器和药筒设备是相当简单的，并包含与饮用水源连接的入口，含有通常处于固定床形式的所述稀土吸收剂的过滤器或药筒，和与水槽水龙头连接的出口，以直接使含氧阴离子耗尽的饮用水离开该药筒或过滤器进入水龙头。或者，药筒或过滤器型的设备可设计安装在水龙头上以使离开水龙头的水在被消费之前穿过该药筒或过滤器设备。
在过滤器或药筒中，一种或多种污染物金属或元素的含氧阴离子与吸收剂中的稀土阳离子发生反应，并且所得到的稀土含氧阴离子化合物被吸附在固定床固体上。在所述药筒或过滤器设备之一的固定床变得被稀土含氧阴离子化合物饱和之后，用相同或相似设计的新的药筒或过滤器替换该药筒或过滤器。用过的药筒或过滤器则以法律批准的方式进行处置。
如此前所提到的，在本发明的备选的实施方案中，用一种或多种溶于水的稀土化合物的溶液代替包含稀土化合物的固体吸收剂来处理所述受污染的含水原料。在本发明的这种实施方案中，将稀土化合物的溶液注入含水原料中以使所述稀土化合物与污染物含氧阴离子反应以将它们以不溶性稀土含氧阴离子化合物的形式沉淀下来。使用足够的稀土化合物以使得含水原料中的含氧阴离子在合理的时间段内沉淀下来。通常，加入到含水原料中的溶液的稀土化合物浓度与该含水原料中的含氧阴离子的浓度相近。可使用的水溶性稀土的实例包括稀土的氯化物、稀土的硝酸盐、稀土的硝酸铵盐和稀土的硫酸盐，优选镧和铈的氯化物、硝酸盐、硝酸铵盐和硫酸盐。
通过如下实施例进一步举例说明本发明的本质和目标，所述实施例仅出于举例的目的而提供，并不对由权利要求所定义的本发明进行限制。实施例表明，使用二氧化铈、氧化镧和它们的混合物，可从水中除去以含氧阴离子形式存在的多种元素。
实施例1-3
在蒸馏水中溶解试剂级的重铬酸钾，由此制备以Cr计算含有1.0ppmw铬的测试溶液。该溶液含有以含氧阴离子形式存在的Cr6+，且不含其它金属含氧阴离子。在玻璃容器中将0.5克氧化镧(La2O3)和0.5克二氧化铈(CeO2)的混合物与100毫升的该测试溶液成浆。用泰氟龙包覆的磁力搅拌棒将所得到的浆料搅拌15分钟。搅拌后，经过Whatman#41过滤纸将水与固体过滤分开，并使用感应耦合等离子体原子发射光谱仪来分析铬。该程序重复两次，但各使用1.0克的氧化镧或二氧化铈(来代替氧代镧和二氧化铈的混合物)与100毫升测试溶液成浆。这三次试验的结果列于下表1。
表1
Figure GSA00000060944100081
可见，氧化镧、二氧化铈和二者等量的混合物有效地从测试溶液中除去大于98％的铬。
实施例4-6
重复实施例1-3的程序，只是使用以Sb计含有1.0ppmw锑的测试溶液代替铬测试溶液。用蒸馏水稀释含有100ppmw锑并含As、Be、Ca、Cd、Co、Cr、Fe、Li、Mg、Mn、Mo、Ni、Pb、Se、Sr、Ti、Tl、V和Zn各100ppmw的经检定的标准溶液，由此制备锑测试溶液。这些测试的结果也列于表1，并表明，两种稀土混合物单独或相混合，有效地从该测试溶液中除去90％或更多的锑。
实施例7-9
重复实施例1-3的程序，只是使用以Mo计含有1.0ppmw钼的测试溶液代替铬测试溶液。用蒸馏水稀释含有100ppmw钼并含As、Be、Ca、Cd、Co、Cr、Fe、Li、Mg、Mn、Ni、Pb、Sb、Se、Sr、Ti、Tl、V和Zn各100ppmw的经检定的标准溶液，由此制备钼测试溶液。这些测试的结果也列于表1，并表明，氧化镧、二氧化铈和二者的等重量混合物有效地从该测试溶液中除去大于99％的钼。
实施例10-12
重复实施例1-3的程序，只是使用以V计含有1.0ppmw钒的测试溶液代替铬测试溶液。用蒸馏水稀释含有100ppmw钒并含As、Be、Ca、Cd、Co、Cr、Fe、Li、Mg、Mn、Mo、Ni、Pb、Sb、Se、Sr、Ti、Tl和Zn各100ppmw的经检定的标准溶液，由此制备钒测试溶液。这些测试的结果也列于表1，并表明，氧化镧和氧化镧与二氧化铈的等重量混合物有效地从该测试溶液中除去大于98％的钒，而二氧化铈除去约88％的钒。
实施例13-15
重复实施例1-3的程序，只是使用以U计含有2.0ppmw铀的测试溶液代替铬测试溶液。用蒸馏水稀释含有1000ppmw铀的经检定的标准溶液，由此制备铀测试溶液。该溶液不含其它金属。这些测试的结果也列于表1，并表明，与实施例10-12相似，氧化镧和氧化镧与二氧化铈的等重量混合物有效地从该测试溶液中除去绝大多数的铀。然而，与那些实施例相似，二氧化铈不能有效地除去约75％的铀。
实施例16-18
重复实施例1-3的程序，只是使用以W计含有1.0ppmw钨的测试溶液代替铬测试溶液。用蒸馏水稀释含有1000ppmw钨的经检定的标准溶液，由此制备钨测试溶液。该溶液不含其它金属。这些测试的结果也列于表1，并表明氧化镧、二氧化铈、和氧化镧与二氧化铈的等重量混合物同等有效地从该测试溶液中除去95％或更多的钨。
尽管已经参照本发明的数个实施方案对本发明进行了描述，显然对于本领域技术人员来说，参照以上的描述做出许多改动、修改和变化是显而易见的。因此，打算将落入所附的权利要求的主旨和范围之内的所有这些改动、修改和变化包含在本发明范围内。

Claims (4)

1.不溶性组合物，包括：
稀土化合物；和
含氧阴离子，所述含氧阴离子具有选自5、13、14、22-25、31、32、40-42、44、45、49-52、72-75、77、78、82、83和92的原子序数的元素。
2.权利要求1的不溶性组合物，其中所述稀土化合物中的稀土选自铈、镧、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇、钪及它们的混合物，其中所述稀土化合物是不溶于水的稀土的氧化物、稀土的水合氧化物、稀土的碳酸盐、稀土的磷酸盐、稀土的氯化物、稀土的硝酸盐、稀土的硝酸铵盐、稀土的硫酸盐或稀土的氟化物。
3.权利要求1的不溶性组合物，其中所述稀土化合物被负载于颗粒状固体基质上，其中所述固体基质具有对所述稀土化合物的阳离子交换能力小于20毫当量每100克，表面积为80-800m2/g，和颗粒尺寸为2-1200微米。
4.权利要求1的不溶性组合物，其中所述稀土化合物被负载于粘土基质上和其中所述粘土基质具有对稀土化合物的阳离子交换能力小于20毫当量每100克。
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