木质素衍生腐植酸制备与应用最新进展

腐殖质(HS)来源于自然腐烂的生物质。HS的主要产物是腐植酸、黄腐酸和腐黑物。HS是从自然资源(如煤、褐煤、森林和河流沉积物)中提取的。然而,从这些资源生产HS并不环保,可能会对生态系统造成影响。早期的理论认为HS可以通过酶促或有氧氧化从木质素转化而来;另一方面,木质素是纸浆和纸张生产过程的副产物,可通过商业获得,然而它仍未得到充分的利用。为了解决环境友好型HS生产和适应木质素增值化进程的挑战,木质素衍生HS的生产引起了人们的关注。目前木质素转化为类HS物质的化学改性途径有碱性有氧氧化、碱性氧化消化、氧化氨解等。本文全面论述了木质素转化为HS的基本要素。综述了天然HS和木质素衍生HS在土壤富集、肥料、废水处理、水净化、医药等领域的应用。此外,还介绍了目前木质素生产和利用HS所面临的挑战。

响应面法优化生物质灰处理TMP废水的工艺条件

研究了生物质灰(FA)去除热磨机械浆(TMP)废水中有机物的工艺条件,利用响应面Optimal Design建立数学模型,考察了FA质量浓度、温度和时间等影响因素对处理效果的影响。结果表明,FA处理TMP废水效果明显,建立的浊度、COD和木质素去除率的模型,拟合情况良好,可预测任意期望值的去除率。增加FA用量、提高处理温度、延长处理时间有助于浊度、COD和木质素去除率的提高。FA处理TMP废水的最佳处理条件为:FA 100g/L,处理温度25℃,处理时间60min。此条件下处理的TMP废水,浊度为27.60NTU,COD为0.44g/L,木质素和半纤维的质量浓度分别为0.04和0.01g/L;浊度、COD和木质素去除率分别为96.2%、79.3%和95.4%。

In-situ polymerization of lignocelluloses of autohydrolysis process with acrylamide

In the present study,the hydrolysates generated via autohydrolysis of spruce wood chips were di-rectly used as feedstock for producing coagulants.The in-situ polymerization of acrylamide(AM)and lignocellulose(LC)of hydrolysates was successfully conducted.The reaction was optimized to generate lignocellulose-acrylamide(LC-AM)with the highest molecular weight(41,060 g/mol)and charge density(-0.25 meq/g)under the optimum conditions,which were 3 h,60◦C,4%(w)initiator based on the dried mass of hydrolysate,and an AM/LC molar ratio of 5.63.A nuclear magnetic resonance(NMR)spectroscopy confirmed the grafting of acrylamide on LC.Other prop-erties of LC-AM were characterized by the elemental analyzer,zeta potential analyzer,gel per-meation chromatography(GPC),and particle charge detector(PCD).The LC-AM was applied as a coagulant for removing ethyl violet dye from a simulated dye solution.The results indicated that 47.2%dye was removed from the solution at a low dosage of 0.2 g/g.The dual flocculation of LC-AM with other polymers for dye removal is suggested to further improve its effectiveness.

Synthetic and lignin-based surfactants:Challenges and opportunities

Surface active agents(surfactants)are chemicals that can accumulate at the surface of a liquid,or interface between two phases with the role of changing the surface tension of the interface.Depending on their structures,they have many applications in industries,such as the petroleum,mining,pulping and textiles,wherein they are utilized as detergents,wetting agents,emulsifiers,foaming agents and dispersants.Most of commonly used surfactants are oil-based chemicals.However,using environmentally friendly feedstocks to produce surfactant is desirable to lessen the environmental impact of surfactant production and use in industry.Lignin is an attractive candidate for this purpose as it is inexpensive and readily available.Lignin and lignin derivatives,such as lignosulfonates,can be chemically modified to produce surfactants with different chemical and physical properties,which makes them suitable for a wide variety of applications.The lignin types and the processes performed for lignin production affect the properties of generated lignin significantly,which in turn influence the reactivity and the efficiency of the reaction for surfactant generation.In this review,the characteristics and applications of oil-based surfactants,and the efforts to produce lignin-based surfactants are reviewed.As oil-based surfactants with altered properties are available in the market,several different pathways can be followed for producing lignin-based surfactants.The advantages and disadvantages of using lignin-based surfactants are also discussed.

Sulfonation of Hydroxymethylated Lignin and Its Application

To valorize kraft lignin,hydroxymethylation and sulfonation were applied on this under-utilized,but vastly available,material.The hydroxymethylation pretreatment was conducted as means to improve the reactivity of lignin.The sulfonation of hydroxymethylated kraft lignin was investigated by sulfuric acid and sodium sulfite treatments under various conditions.The modified lignin samples were characterized for their charge density,solubility,elemental components,and molecular weights.The results showed that the hydroxymethylation facilitated the sulfonation by sodium sulfite,yielding a product(SSH-lignin)with the charge density of-1.2 meq/g and water solubility of 10 g/L under the conditions of Ns_(2)SO_(3)/lignin molar ratio of 0.49 mol/mol,95℃and 3 h.On the other hand,hydroxymethylation hindered the sulfonation of lignin by sulfuric acid,yielding a product(SAH-lignin)with the charge density of–0.46 meq/g and solubility of 0.9 g/L under the conditions of H_(2)SO_(4)/lignin molar ratio of 14.8 mol/mol,80℃and 1 h.The SSH-lignin had a high adsorption on kaolinite(17 mg/g)at a lignin concentration of 40 g/L.The sulfonated lignins were also found to be effective coagulant for the cationic dye ethyl violet.

Leaching characteristics of biomass fly ash in water and a TMP spent liquor:a case study

Fly ash is considered as an under-utilized product of pulp and paper industry and is mainly land-filled.However,it can be repurposed as an adsorbent for organics of wastewater effluents.Despite efficient adsorption capability,its metal components may dissolve in wastewater and harm the environment.This investigation focused on the leaching behavior of metals from biomass-based fly ash in water at pH 6 and 12.5.A similar investigation was performed in the spent liquor of a pulping process to evaluate the extraction of metals from fly ash in such an environment that fly ash could be used as an adsorbent.The results revealed that the predominant metals leached from fly ash in water and the spent liquor were Ca,K,Mg,Mn,Na,and Si.The trace metals including Al,Ba,Sr,and Zn were also detected to a significant extent.Interestingly,the extraction of metals from fly ash in spent liquor was more limited than in water,which is beneficial for the application of fly ash in spent liquors.