The n-i-p-i design is of particular interest for materials with short diffusion lengths, such as dilute nitrides.
Furfural and 5-hydroxymethylfurfural (HMF) are inhibitors generated by lignocellulosic biomass pretreatment such as dilute acid hydrolysis that inhibit microbial growth and interfere with subsequent fermentation.
Biotechnological downstream processing faces several challenges, such as dilute product streams and contained target products which are sensitive to heat, oxidation, other chemicals, etc. State-of-the-art separation methods, e.g. chromatography, are not always the best option due to variable yield losses and high costs.
Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride salts.
This work also provides an example showing how synthetic lignocellulosic hydrolysates derived from other pretreatment technologies (such as dilute acid and steam explosion) can be formulated.
The most widely investigated pretreatment technologies are thermochemical treatments such as dilute acid treatment (with or without rapid steam decompression (explosion)) [ 8- 10] and ammonia pretreatment [ 11, 12].
Unlike other pretreatments, such as dilute acid, which extract a significant amount of hemicellulose [ 11], AFEX cleaves lignin-carbohydrate complexes without physically extracting hemicellulose or lignin into separate process streams [ 13, 15, 16].
The digestibility of these components is increased by pretreatment processes such as dilute acid, alkali, hot compressed water, and milling treatments that disrupt the rigid structural network consisting of cellulose-hemicellulose-lignin [ 3].
Low and neutral pH pretreatment technologies such as dilute acid for the former and liquid hot water for the latter usually remove a large fraction of the hemicellulose from biomass, but remove very little lignin.
It is mentioned that the removal of cement after use is readily accomplished by passing acids such as dilute hydrochloric acid in contact with cement until it dissolves or decomposes [ 29].
Currently, thermochemical approaches such as dilute acid and steam-explosion pretreatment can offer high fermentable sugar yields for biorefinery, but these processes usually require high temperatures and operating pressures [ 5, 6].
