Biochar from Oil Cakes: An Ecient Adsorbent for the Removal of Acid Dyes From Wool Dye House Euent

Textile dyeing industries are one of the major culprits for environmental pollution. The industries are 13 adopting various processes for the removal of dyes and chemicals from the effluent before disposing to the land or 14 water bodies. In the reported study, biochars were prepared from almond, coconut, and mustard oil cakes by 15 chemical activation with phosphoric acid followed by low temperature pyrolysis. The ball milling technique was 16 employed to reduce the particle size of the biochars below 300 nm. The synthesized biochars were used for the 17 removal of color from the acid dye effluent from the wool dyeing unit. The results showed that very small quantities 18 (2.0 %) of biochars are sufficient to remove around 92% color from the dye effluent. The batch adsorption and 19 kinetic studies indicate the highest efficiency of color removal for the biochar derived from almond oil cake, 20 followed by mustard and coconut. The adsorption properties of the synthesized biochars were found to be greatly 21 depending on the type of oil cake used. It is concluded that the biochars produced from the oil cakes may be a partial 22 replacement of petroleum based activated carbon for the color removal from wool textile dye effluent. better efficiency than others with 92 % color removal efficiency. Due to the low temperature pyrolysis, though the performance of the synthesized biochars is expected to be slightly lesser than the commercial activated carbon produced from petroleum products, the cost may be justified with low cost precursor. Acid dyes are commonly 261 employed for the dyeing of wool fabric. In comparison with reactive dyeing of cotton, due to the high affinity of 262 acid dyes on wool, they produce very few remnant dyes in the dye bath. Here, the high-cost activated carbon may be 263 partially or fully replaced with low-cost biochars produced from agro residues. The study concluded that the 264 biochars produced from low cost agro processing residue - oil cakes can effectively transform into high-value 265 biochars and the said biochars can be used for the removal of color from acid dye effluent from wool dye house.


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Textile industries opened up large employment opportunities in many countries. On another hand, they are 26 causing environmental pollution also. Many countries imposed stringent regulations for the disposal of dye effluents 27 to the land or nearby water bodies. The buyers are also conducting strict auditing in their production units to ensure 28 that the supplier is maintaining all ecological regulations from the raw material to the end product. Thus, to fulfill 29 the government regulations and customer demands, the textile industry need to stick on eco-friendly processing techniques to the maximum possible extent. The use of enzymes for pretreatment, high exhaustive dyes, and herbal 31 colors are some of the good initiative steps taken in this regard.

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During the dyeing process, depending upon the class of dye and the nature of the textile fiber, it is 33 estimated that 15-20 % of the dyes remained in the dye bath and discharged as effluent. The dye house effluents may 34 contain heavy metals, ammonia, acids, alkalies, salts, and large amounts of pigments, many of which are toxic and 35 low bio-degradable materials (Crini, 2006; Mohan and Karthikeyan., 2004). The textile industrial effluents are 36 subjected to various treatments before discharging into the water bodies or land. The main methods used to treat 37 colored effluents are oxidation, coagulation, flocculation, biological treatment, and membrane filtration. The 38 disposal of improperly treated dye house effluent may cause a menace to the quality of the receiving water bodies, 39 the aquatic eco-system, and humans due to objectionable color, odor, high BOD and COD, TDS, and other toxic

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In the present attempt, biochars were prepared from almond, coconut, and mustard oil cakes through 61 chemical activation followed by pyrolysis. The physical and adsorption characteristics of the biochars were 62 investigated. The synthesized biochars were employed for the removal of color from acid dyes of real textile dye 63 effluent from the wool processing pilot plant using batch adsorption experimental studies.

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Oil cakes used for the study were collected directly from oil mills from various locations of India and used 66 without further purification. Optilan Turquiose (acid dye) was purchased from local dye suppliers, Jaipur, India.

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India.  The oil cakes of almond, coconut, and mustard were pulverized in a grinder. The finely powdered oil cakes Yield of Biochar = (weight of biochar/ weight of oil cake) x 100 (1)

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The particle size of the biochars was further reduced by 2 h of ball milling in Pulverisette (model-6

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ClassicLine, Fritsch, Russia).To narrow down the experiment, a preliminary exercise was conducted. The dye 89 effluent was treated with 0.5 % weight percentage of each adsorbent for 30 min and the absorbency values were 90 noted (Table 1). Based on the absorbency value, the best one from each oil cake was selected for further 91 characterization and batch adsorption studies, namely 2.5 N PAB, 1.0 N PCB, and 2.5 N PMB.

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The particle size of biochar was analyzed using the Malvern Mastersizer (model -3000) particle size 96 analyzer. FTIR analysis was performed for the identification of functional groups present in the bare oil cakes and 97 the synthesized biochar using the Brucker double beam spectrophotometer (model -Alpha). The spectra were 98 measured from 4000-500 cm -1 . Dispersion (0.1 %) of biochar in water was sonicated before feeding to the particle 99 size analyzer to deter agglomeration. The morphology of the biochar was analyzed by SEM analysis using Nova For the analysis of bulk density, 3.0 g of adsorbent was taken in a 10 ml measuring cylinder and tightly packed 108 without voids. The density was determined from the ratio of mass to volume. Adsorbent (0.5 g) was kept at 105 ºC 109 for 6 h. The moisture content of the adsorbent was analyzed from the difference in the weights before and after 110 drying. For porosity measurement, 2.5 ml distilled water was added to 1.5 g adsorbent in a 10 ml measuring   The physical properties of the selected biochars are shown in Table 2. The yield of the biochar was found    pyrolysis process, the acids react with oil cake and create pores due to the evaporation of volatile gases (Yue, 1995).

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The number of pores per unit area produced by H3PO4 treated almond is high as confirmed by porosity studies. The One of the critical parameter of biochar is its BET surface area to characterize the adsorption phenomenon.

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The BET analysis of 2.5 N PAB was performed as described earlier and the results are tabulated in Figure

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Currently, petroleum-based activated carbon is successfully employed to remove the residual color from 252 the textile effluent. Textile industries are always searching for efficient replacement of existing high-cost materials 253 for effluent treatment. In this context, an attempt was made to prepare biochars from low-cost oil cakes and used it 254 for the removal of color from the acid dye from wool dye effluent collected from the pilot plant. Phosphoric acid 255 treatment followed by a low temperature pyrolysis converted the oil cakes into biochars. The micro and nano-sized 256 pores produced inside the biochar was found to be effective for the dye adsorption. Whilst the same protocol was 257 employed for the preparation of biochars from all oil cakes, the biochar developed from almond was found to have 258 a b better efficiency than others with 92 % color removal efficiency. Due to the low temperature pyrolysis, though the 259 performance of the synthesized biochars is expected to be slightly lesser than the commercial activated carbon 260 produced from petroleum products, the cost may be justified with low cost precursor. Acid dyes are commonly 261 employed for the dyeing of wool fabric. In comparison with reactive dyeing of cotton, due to the high affinity of 262 acid dyes on wool, they produce very few remnant dyes in the dye bath. Here, the high-cost activated carbon may be 263 partially or fully replaced with low-cost biochars produced from agro residues. The study concluded that the 264 biochars produced from low cost agro processing residue -oil cakes can effectively transform into high-value 265 biochars and the said biochars can be used for the removal of color from acid dye effluent from wool dye house.