Friday, 22 February 2019

Microwave pyrolysis in Malaysia

Journal of Chemical Technology & Biotechnology, 2019

BACKGROUND: Oil palm shell (OPS) is a biomass widely available from palm oil mills. Self-purging microwave pyrolysis (SPMP) was performed to produce carbon-rich biochar from OPS for the adsorption of methylene blue dye. The effect of feedstock amount on the pyrolysis temperature, yield and characteristics of the biochar were investigated.

RESULT: The amount of feedstock was directly proportional to the final pyrolysis temperature. The pyrolysis reached a maximum final temperature of 760 ∘C when ≥300 g of OPS was loaded into the reactor without microwave absorbent. A heating rate of up to 105 ∘C min−1 was recorded, producing a yield of 40wt% of biochar at a short processing time of 20 min. The biochar obtained at 700 ∘C showed relatively low volatile matter (24wt%), higher fixed carbon content (66wt%), carbon (78.5 wt%), oxygen (17.7 wt%), a highly porous structure with high BET surface area of 410m2 g−1 and pore volume of 0.16 cm3 g−1, and recorded a methylene blue dye adsorption efficiency of 20mg g−1.

CONCLUSION: The SPMP approach showed exceptional promise to produce biochar with low H/C ratio (0.5) and O/C ratio (0.2), which indicated a high degree of carbonization and stability of the biochar to act as a durable agent in wastewater treatment.

Thursday, 21 February 2019

Biochar & mushroom cultivation - Malaysia & China

Journal of Chemical Technology & Biotechnology, 2019

BACKGROUND: Spent mushroom substrate (SMS), largely produced as an agriculture waste from mushroom cultivation, was transformed into biochar via microwave vacuum pyrolysis under different ratios of SMS to microwave absorbent (1:1, 1:2, and 1:3). The biochar was then examined for its potential to be re-used in mushroom cultivation as a growth medium added to conventional mushroom bag log (plastic bag with mushroom seeds and culture substrates containing rice straw, sawdust, lime and water), with emphasis on its ability to form mycelium – a fungus that grows into mushroom from its seeds.
RESULT: The pyrolysis generated up to 36 wt% biochar yield with a large adsorption area (up to215m2 g-1) and less water (4 wt%), indicating that many adsorption sites are available on which mushroom seeds, nutrient and water can be adsorbed onto in order to form mycelium (and subsequently mushroom). The biochar added to grow mushroom in bag log recorded a higher water retention percentage (up to 59%), a higher mycelium colonization length in 8 days (6.3 cm), coverage area (up to 259 cm2) and total mycelium growth volume (317 cm3), and resulted in a higher yield of mushroom (200 gmonth-1) than that recorded for the conventional bag log without biochar (160 gmonth-1).
CONCLUSION: The results indicated that biochar produced from SMS using microwave vacuum pyrolysis shows great potential in retaining water and nutrient that in turn promotes the formation of mycelium that leads to increased growth of mushroom in its cultivation.

Thursday, 14 February 2019