Amination of biochar surface from watermelon peel for toxic chromium removal enhancement

Watermelon peel residues were used to produce a new biochar by dehydration method. The new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI) ions from aqueous solution has been investigated. Three biochars, Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, were made from watermelon peel via dehydration with 50% sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_2 or Triethylenetetramine(TETA) to give Melon-BO-TETA. The prepared biochars were characterized by BET, BJH,SEM, FT-IR, TGA, DSC and EDAX analyses. The highest removal percentage of Cr(VI) ions was 69% for Melon-B,98% for Melon-BO-NH_2 and 99% for Melon-BO-TETA biochars of 100 mg·L~(-1) Cr(VI) ions initial concentration and 1.0 g·L~(-1) adsorbents dose. The unmodified biochar(Melon-B) and modified biochars(Melon-BO-NH_2 and Melon-BO-TETA) had maximum adsorption capacities(Qm) of 72.46, 123.46, and 333.33 mg·g~(-1), respectively.The amination of biochar reduced the pore size of modified biochar, whereas the surface area was enhanced.The obtained data of isotherm models were tested using different error function equations. The Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, respectively. The adsorption rate was primarily controlled by pseudo-second–order rate model. Conclusively, the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption process. The adsorption for the Melon-B, Melon-BO-NH_2 and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction.     

钡盐法处理六价铬电镀废水及最优工艺参数研究

使用钡盐法对铬废水处理,对p H值在废水中的初值、反映温度计量结果、重铬酸钾的浓度等,在回收六价铬的影响效果进行了分析。对废水中的六价铬使用了源自吸收的分光光度法回收。经过处理后,废水中的p H为8~9的时候,六价铬的回收在9%。废水中的六价铬随着其浓度不断上升增加。超过10℃的时候,六价铬的反应没有非常大的影响,但是当温度降低到10℃以下的时候,回收率就逐步下降了。经过处理之后,六价铬的浓度达到了0.276 7 mg/L,达到了相关规定的标准。     

Research on Chromium Retrieval of Black Soil with Hyperspectral Imagery in Northeast of China#br#

According to the definition of spectral integral，a new spectral characteristic parameter，with the name Reversed Spectral Absorption Integral(RSAI)，is proposed and used to retrieve the chromium content based on the Partial Least Squares Regression(PLSR) model.The contrastive study with other traditional spectral characteristic parameters，including differential transformation，inverse transformation，absorption area，etc.indicates that(1) the first derivation of square root transformed model can predict the chromium content quantitatively in terms of spectral transformations.(2) the stability of the absorption area model is slightly poor，and the chromium content of samples can only be estimated roughly.(3) However，as to the inversed spectral absorption integral model，the adjustment determination coefficient(Ad-R²) of the modeling and verification is 0.73 and 0.77，while the Root Mean Squared Error(RMSE) is 2.63 mg/kg and 2.36 mg/kg respectively with Relative Percent Deviation(RPD) being 3.21，which shows that the RSAI model has excellent prediction ability.So，the inversed spectral absorption integral new model can improve the accuracy and stability used to retrieve the chromium content，which provides a new idea for monitoring the chromium contamination in soil.     

余热热处理对热变形低铬半钢耐磨性的影响

通过冲击磨损试验，测试了变形低铬半钢耐磨性，并对其磨损面特征进行了分析。结果表明：该钢变形后经适当的余热热处理可获得较高的耐磨性能。     

Cr对低碳Si-Mn系TRIP钢组织与力学性能的影响

主要研究了Cr对低碳Si-Mn系TRIP钢组织与力学性能的影响。首先利用Formastor-F型膨胀仪测定了含Cr和不含Cr两种低碳钢的连续冷却转变(CCT)曲线,分析指出了Cr对连续退火工艺的潜在影响;然后采用Gleeble-3800热/力模拟试验机对两种钢的薄板试样进行了连续退火模拟实验,并通过拉伸试验测定了力学性能;最后采用金相、扫描电镜、X-射线衍射分析等技术考察分析了两种钢的显微组织。结果表明:含Cr的TRIP钢的组织比较细小,铁素体晶粒近似等轴分布;两种TRIP钢的残余奥氏体含量相近,但含Cr钢的残余奥氏体中的含碳量较高。分析认为这是由于含Cr钢在热轧阶段较易生成细小的组织,而在热处理阶段则抑制贝氏体的生成,最终获得稳定的残余奥氏体。     

珠钢不锈钢冶炼技术探讨

本文阐述了不锈钢冶炼的关键技术，为生产准备提供帮助。     

Is evidence-based practice diverse enough? Philosophy of science considerations.

In its policy rationale for evidence-based practice in psychology (EBPP), the APA Presidential Task Force on Evidence-Based Practice (see record 2006-05893-001) claims to have constituted itself with "scientists and practitioners from a wide range of perspectives and traditions, reflecting the diverse perspectives within the field" (p. 273). We applaud this attention to diversity but contend that an entire perspective of the debate was omitted in the Task Force's newly approved policy and its underlying report. The failure to consider a philosophy of science perspective led the Task Force to make a number of epistemological assumptions that are not based on evidence or rationale and that thus violate the very spirit of evidence-based decision making. In this comment, we reveal a few of these assumptions and discuss their detrimental consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ATM网络的可用比特率业务

本文介绍了可用比特率业务的业务特点，速率控制机制以及该业务存在的问题。     

抗高温磨损高铬铸铁的研究

经Mo、B、V、Ti合金化和RE变质处理的高铬铸铁，具有优良的抗高温磨损性能和强韧性，用于制造筛分高温烧结矿的振动筛筛板，使用寿命比ZG30Cr18Mn12Si2N耐热钢筛板提高2倍以上。多元高铬铸铁筛板制造工艺简单，成本低，值得在筛分领域推广使用。     

Transport of chromium(VI) through a Cyanex 921‐supported liquid membrane from HCl solutions

The transport of chromium(VI) through a flat‐sheet supported liquid membrane containing Cyanex 921 as a carrier has been investigated. The permeation of the metal is investigated as a function of various experimental variables: hydrodynamic conditions, concentration of chromium(VI) and HCl in the feed phase, carrier concentration and diluent in the membrane and strippant concentration in the stripping phase. The mass transfer coefficient and the thickness of the aqueous boundary layer were calculated from the experimental data. Furthermore, the selectivity of Cyanex 921‐based flat‐sheet supported liquid membrane towards different metal ions and the behaviour of the system against other carriers are presented. Copyright © 2003 Society of Chemical Industry