Moisture Content and Mechanical Properties of Bio-Waste Pellets for Fuel and/or Water Remediation Applications

Abstract

The current research is focused on the mutual comparison (mechanical properties, response to humidity) of agro-waste composite materials. The purpose of this work is directed at the valorization of agro-waste biomass products and to investigate their mechanical stability for transport or other applications (in dry and wet states). Three different types of agro-waste (oat hull (Oh), torrefied wheat straw (S), and spent coffee grounds (SCG)) were blended with kaolinite (K) and chitosan (CHT) at variable weight ratios to yield ternary composites. Mechanical properties were represented by measuring hardness (in compression mode) and elastic modulus (under tension mode). Young’s (elastic) modulus was measured both for dried and hydrated samples. The pelletized materials were prepared in two forms: crosslinked (CL) with epichlorohydrin and non-crosslinked (NCL). The hardness of the Oh pellets was poor (75 N) and decreased by four times with greater agro-waste content, while crosslinking affected the hardness only slightly. S pellets had the highest level of hardness at 40% agro-waste content (160 N), with a concomitant decrease to 120 N upon crosslinking. SCG pellets had the least change in hardness for both CL and NCL specimens (105–120 N). The trends of Young’s modulus were similar to hardness. Hydration caused the elastic modulus to decrease ca. 100-fold. In general, S and SCG composites exhibit the greatest hardness and Young’s modulus compared to Oh composites (CL or NCL) in their dry state.

Eggshell incorporated agro-waste adsorbent pellets for sustainable orthophosphate capture from aqueous media

“…2 in ref. 21 for a comparable pellet system 21 ). However, the TWCs can undergo solvent swelling and expansion in aqueous media because of the presence of pores and the polar surface groups due to chitosan.…”

“…32,33 The utility of eggshells as additives for P i capture and release media has been reported for ES in calcined forms. 34 This research aims to expand the development of sustainable adsorbents for orthophosphate capture and release through the design of composites that require lower energy and less demanding synthesis via physical compositing of renewable feedstocks 11,21,22 to afford enhanced P i capture.…”

“…In turn, torrefaction of biomass affords improved properties such as handling, processing, and environmental stability. 11,17–23…”

Pyridinium-furfuryl-modified granular agro-waste adsorbent for orthophosphate recovery

“…21,22 Biomass composites derived from spent coffee grounds or torreed wheat straw have favourable stability in aqueous media, especially under acidic conditions versus non-torreed biomass such as oat hulls. 20,23 As well, composites with greater oat hull content, especially above 40-60% display limited mechanical stability, as evidenced by crumbling in the dry state. Hardness of such composites in the dry state was measured around 20-30 N for non-crosslinked and ca.…”

“…Furthermore, these composites show susceptibility to breakdown in aqueous media with low salinity or slight acidity as outlined in previous research. 19,23 In turn, surface modication is required to reach acceptable mechanical strength and continued resilience in aqueous media for remediation applications in dynamic environments. For the case of aqueous media in many river systems, pH conditions reside near 7-8, where anion adsorption by chitosan can become attenuated or negligible.…”