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首页> 外文期刊>Transactions of the ASABE >Evaluating Simple, Low-Cost Techniques to Estimate Molecular Weights and Charge Densities of Polydisperse Commercial Polyacrylamides for Soil and Sediment Applications
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Evaluating Simple, Low-Cost Techniques to Estimate Molecular Weights and Charge Densities of Polydisperse Commercial Polyacrylamides for Soil and Sediment Applications

机译：评价简单，低成本的技术以估算用于土壤和泥沙应用的多分散商业聚丙烯酰胺的分子量和电荷密度

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摘要

Nonionic and anionic polyacrylamides (PAMs) are being used more extensively in soil erosion prevention and sediment control applications. Of their various physicochemical properties, the molecular weight (MW) and charge density (CD) of PAMs have been reported as being the most important characteristics for soil stabilization and sediment flocculation. However, these properties rarely have been measured by researchers or practitioners in the fields of soil and environmental sciences, presumably due to the difficulty of the measurements or lack of access to proper equipment. The objective of this research was to demonstrate the applicability of two relatively simple, low-cost approaches for estimating CDs and MWs of polydisperse, commercially available PAMs. Values obtained with the simple measurement techniques (acid-base titration for CD, viscosity determination for MW) were compared to those measured using sophisticated state-of-the-science techniques (carbon-hydrogen-nitrogen (CHN) elemental analysis for CD, multi-angle laser light scattering for MW). Measured CD and MW values were also compared to the values provided by PAM vendors when available. Results from the simple titration method were in excellent agreement with the more complicated CHN analysis for CD values, with differences never more than ± 8%. In contrast, values provided by vendors had deviations in CDs ranging from -30% to +17% from measured CHN values and were never closer than 7% absolute difference. Replicate measurements resulted in a coefficient of variation in CD values ranging from 2% to 15% using the CHN technique, but only a 0.2% to 3% coefficient of variation with the simple titration method. Molecular weights estimated from the simple viscosity technique were lower than those obtained from multi-angle laser light scattering, a factor that reflected the viscosity- versus weight-average MWs of our polydisperse commercial PAM samples. Because quantitative MW information often may not be provided by vendors, as well as the fact that common application practices may lead to shear forces that reduce the MW, we believe viscosity-based MW values should be satisfactory for most users of commercial PAM products. Additional simplifications and modifications that we suggest in this article will make both the titration and viscosity techniques useful for a wide variety of PAM users, particularly those who do not have access to sophisticated analytical laboratories but yet have the need to maintain adequate quality assurance and control in their soil erosion prevention and sediment control applications
机译：非离子和阴离子聚丙烯酰胺（PAM）在土壤侵蚀预防和沉积物控制应用中得到了更广泛的应用。据报道，PAMs的各种物理化学性质是其分子量（MW）和电荷密度（CD），是土壤稳定和沉淀物絮凝的最重要特征。但是，这些性质很少由土壤和环境科学领域的研究人员或从业人员测量，大概是由于测量困难或缺少适当设备的缘故。这项研究的目的是证明两种相对简单，低成本的方法可用于估算多分散的市售PAM的CD和MW。将使用简单的测量技术（用于CD的酸碱滴定，用于MW的粘度测定）获得的值与使用复杂的科学技术（用于CD的碳氢氮（CHN）元素分析，多种角激光散射（兆瓦）。可用的CD和MW值也与PAM供应商提供的值进行了比较。简单滴定法的结果与CD值的更复杂的CHN分析非常吻合，差异永远不超过±8％。相反，供应商提供的值与CD的测量CHN值相比，CD的偏差在-30％到+ 17％之间，并且绝对不会超过7％的绝对差。使用CHN技术，重复测量得出CD值的变异系数在2％至15％之间，而使用简单滴定法只能得到0.2％至3％的变异系数。通过简单粘度技术估算的分子量低于通过多角度激光散射获得的分子量，这反映了我们的多分散市售PAM样品的粘度对重均分子量。由于供应商可能通常无法提供定量的MW信息，以及常见的应用实践可能导致剪切力降低MW的事实，因此我们认为基于粘度的MW值对于大多数商用PAM产品用户而言应该是令人满意的。我们在本文中建议进行的其他简化和修改将使滴定和粘度技术对各种PAM用户都有用，特别是那些无法使用复杂的分析实验室但仍需要保持足够质量保证和控制的用户在土壤侵蚀预防和沉积控制中的应用

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