Journal of Cleaner Production 421 (2023) 138440 Available online 12 August 2023 0959-6526/© 2023 Published by Elsevier Ltd. A novel combinatorial approach for cleaner production of biodegradable sheets from the combination of paddy straw and pine needle waste Akansha Gupta a , Amrita Preetam a , Pooja Ghosh a, * , Kalpana Arora b , Satyawati Sharma a , Vivek Kumar a , Manish Kumar c a Centre for Rural Development and Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India b Centre for Technology, Society of Economics and Social Science, India c School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India A R T I C L E INFO Handling Editor: Pai Zheng Keywords: Paddy straw Pine needles Enzymatic pulping Hand sheets Response surface methodology ABSTRACT The study aims at providing a cleaner technology by employing a combinatorial approach of mild chemical treatment of 1% Ca(OH) 2 followed by Phanerochaete chrysosporium, (laccase producer) on paddy straw and pine needles in combination, for getting cellulose-rich pulp for making biodegradable paper sheets. Response surface methodology was adopted by choosing two response parameters – cellulose content and residual lignin content after pulping to optimize the cooking conditions. The pulp derived after optimizing the parameters i.e., solid: liquid ratio (1:7), temperature (160 ◦ C), time of digestion (60 min), and NaOH concentration (4%) was char- acterized. SEM and FTIR analysis, showed a more condensed cellulose network and –OH bonds when compared with alpha-cellulose. Best pulp (kappa no. 24 and ֯SR 59) was casted to produce biodegradable paper sheets of different GSM types (40, 50, 75, 100 GSM), and their different mechanical properties were tested. The maximum tensile strength (110 Nm/g) and Cobb index (345.77 g/m 2 ) were seen in 100 GSM sheets which is comparable with regular corrugated sheets. 1. Introduction Strict laws on deforestation and cutting of trees to extract metabo- lites, pulp for paper making, and other key constituents are in stringent jurisdictions. Due to increasing concerns about present raw material (wood pulp) being used by pulp industry, it has become important for the these industries to shift their focus on other lignocellulosic alterna- tives such as paddy straw, husk, and bagasse to extract cellulose from biomasses (Duan et al., 2016). Also a recent shift is observed from traditional biomasses to perennial grasses, such as switch grass, elephant grass, citronella grass, Sabai grass etc. Citronella grass (Cymbopogon winterianus) pulped by hydrothermal method showed 32.7% of alpha-cellulose content and 24% of lignin content. Hand sheets devel- oped by this pulped grass showed tensile index of 31.7 Nm/g (Sharma et al., 2022). Fibre length of the Kraft pulp derived from Citronella grass was between 0.67 and 7 mm and fbre with was between 0.13 and 0.17. Melia dubia is one of the perennial hardwood trees which have recently gained importance in pulp industry. Pulp extracted from such trees shows a better yield of 51–52% and kappa number 8.1. Hand sheets prepared from Kraft pulp showed tensile index of 83.61 Nm/g and tear index of 6.19 mNm 2 /g. Palm oil stems after oil extraction are one of the potential biomasses that could be pulped by ethanolamine pulping and could be further applied to make hand sheets (Deepika and Lal, 2019; Anupam et al., 2021). This practice of harnessing cellulose from some potential biomass could solve many problems. Firstly, biomass can be utilized in one of the greener ways and thus contribute to a value-added product chain, and secondly, deforestation of the land can be minimized. Paddy straw is one of the nastiest biomasses in tropical and sub-tropical countries where rice is one of the most majorly cultivated grains and also the staple diet for the majority of the population (Geetha Thanuja et al., 2022). Paddy residue, after harvesting the grain is left in farms for several days and fnally burnt which contributes to huge particulate contamination in the air successively causing respiratory issues and low visibility during winter mornings due to smog formation (Singh and Kumar 2019). Pine needles are a major problem causing biomass in hilly terrains due to their disposal issue and also a major root cause for forest fres and biodiversity loss specifcally in the summer season, needles lose moisture and catch fre due to sunshine and friction (Kala and Subbarao, * Corresponding author. E-mail addresses: pooja.ghosh9@gmail.com, poojaghosh@iitd.ac.in (P. Ghosh). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2023.138440 Received 26 March 2023; Received in revised form 4 July 2023; Accepted 11 August 2023