Synthesis and Characterization of Plant Activated Charcoal (PAC) for Remediation of Pollutants from Industrial Effluents - An Efficient Tool for Pollution Abatement at Industrial Scale

The aim of this work was to prepare Plant Activated Charcoal (PAC) from organic matters (Coconut Husk: CH, Sugarcane Bagasse: SB) for removal of nutrients and heavy metals from industrial effluents, Central Gujarat, India. Industrial wastewater was obtained from Paint Industry (PI), Vallabh Vidyanagar STP (VVS), Petlad STP (PS) and Organic Chemical Industry (OCI). Objectives of study were synthesis and characterization of PAC (CH, SB), optimization of PAC at different pH, concentration, time duration and agitation rate, remediation of nutrients and heavy metals from selected industrial effluents using PAC. Optimization efficiency of CH: pH 8, 10 ppm Conc., 36.00% removal; pH 8, 20 ppm Conc., 29.30% removal; pH 8, 30 ppm Conc., 40.16% removal; pH 8, 40 ppm Conc., 38.05% removal; pH 8, 50 ppm Conc., 74.86% removal; pH 8, 50 ppm Conc., 100 rpm, 72.16% removal; pH 8, 50 ppm Conc., 120 min., 76.52% removal; pH 8, 50 ppm Conc., 500 mg PAC, 81.14% removal. Optimization efficiency of SB: pH 8, 10 ppm Conc., 34.50% removal; pH 8, 20 ppm Conc., 31.20% removal; pH 8, 30 ppm Conc., 40.70% removal; pH 8, 40 ppm Conc., 42.82% removal; pH 8, 50 ppm Conc., 69.48% removal; pH 8, 50 ppm Conc., 100 rpm, 72.70% removal; pH 8, 50 ppm Conc., 120 min., 75.70% removal; pH 8, 50 ppm Conc., 500 mg PAC, 81.70% removal. CH exhibited efficient removal of Sulphate (97.28% each-PI, VVS), 92.13% (PS), 63.71% (OCI). SB was proved to be efficient in removing Sulphate (92.65%-PI), 94.29% (VVS), 92.46% (PS) and 85.08% removal of Chloride (OCI). Utmost removal of Phosphate was observed by CH (94.76%) compared to SB (88.25%-PI), Sulphate (CH: 97.28% each-PI, OCI, SB: 94.29%-VVS), Nitrate (CH: 12.05%-OCI, SB: 10.85%-PI), Iron (CH: 18.69%-PI, SB: 14.24%-PI), Chromium (CH: 21.00%-OCI, SB: 45.38%-PS), Ca (CH: 22.86%-VVS, SB: 40.00%-PS), Mg (CH: 18.61%-OCI, SB: 47.20%-PS), Chloride (CH: 60.00%-OCI, SB: 85.08%-OCI). Comparative study among selected industrial units revealed 97.28% (CH) and 92.65% (SB) removal of Sulphate in PI; 92.13% (CH) and 94.29% (SB) removal of Sulphate in VVS; 92.13% (CH) and 92.46% (SB) removal of Sulphate in PS; 63.71% (CH) removal of Sulpahte and 85.08% (SB) of Chloride in OCI. At the end of the experiment, CH treatment was found to be efficient in removing Sulphate (97.28%) in PI, followed by 92.13% each in VVS & PS, and 63.71% in OCI. On the other hand, SB treatment exhibited effectual removal of Sulphate (94.29%) in VVS, followed by 92.65% in PI, 92.46% in PS and 85.08% removal of Chloride in OCI. Overall, CH treatment was proved to be more consistent in removing Sulphate (97.28%-PI) than SB (94.29%). Surprisingly, SB exhibited exclusive elimination of Chloride (85.08%) in OCI. The outcomes of present study proves the most effective usage of CH and SB as PACs for removal of nutrients and heavy metals for wastewater yields and proportionate use of natural plant wastes as operational tools for wastewater treatments at various industrial scales.

本研究旨在以有机物料——椰壳（Coconut Husk, CH）、甘蔗渣（Sugarcane Bagasse, SB）——制备植物基活性炭（Plant Activated Charcoal, PAC），用于去除印度古吉拉特邦中部工业废水中的营养盐与重金属。实验所用工业废水取自涂料工业（Paint Industry, PI）、Vallabh Vidyanagar污水处理厂（Sewage Treatment Plant, STP, VVS）、Petlad污水处理厂（STP, PS）及有机化工企业（Organic Chemical Industry, OCI）。

本研究的目标为合成并表征椰壳基与甘蔗渣基植物基活性炭，优化不同pH值、初始浓度、反应时长及搅拌速率下的PAC吸附工艺参数，并利用PAC去除所选工业废水中的营养盐与重金属。

椰壳PAC的优化吸附效率如下：pH=8、初始浓度10 ppm时，去除率36.00%；pH=8、20 ppm时，去除率29.30%；pH=8、30 ppm时，去除率40.16%；pH=8、40 ppm时，去除率38.05%；pH=8、50 ppm时，去除率74.86%；pH=8、50 ppm且搅拌速率100 rpm时，去除率72.16%；pH=8、50 ppm且反应时长120 min时，去除率76.52%；pH=8、50 ppm且投加500 mg PAC时，去除率81.14%。

甘蔗渣PAC的优化吸附效率如下：pH=8、初始浓度10 ppm时，去除率34.50%；pH=8、20 ppm时，去除率31.20%；pH=8、30 ppm时，去除率40.70%；pH=8、40 ppm时，去除率42.82%；pH=8、50 ppm时，去除率69.48%；pH=8、50 ppm且搅拌速率100 rpm时，去除率72.70%；pH=8、50 ppm且反应时长120 min时，去除率75.70%；pH=8、50 ppm且投加500 mg PAC时，去除率81.70%。

椰壳PAC对硫酸盐的去除效果优异，涂料工业、Vallabh Vidyanagar污水处理厂废水的去除率均为97.28%，Petlad污水处理厂废水为92.13%，有机化工企业废水为63.71%。甘蔗渣PAC对硫酸盐的去除表现良好：涂料工业废水去除率92.65%，Vallabh Vidyanagar污水处理厂废水为94.29%，Petlad污水处理厂废水为92.46%；其对有机化工企业废水中氯化物的去除率达85.08%。相较于甘蔗渣PAC在涂料工业废水中88.25%的去除率，椰壳PAC对磷酸盐的去除效果更佳，达94.76%。其余污染物的去除情况如下：硫酸盐方面，椰壳PAC在涂料工业、有机化工企业废水中去除率均为97.28%，甘蔗渣PAC在Vallabh Vidyanagar污水处理厂废水中去除率为94.29%；硝酸盐方面，椰壳PAC在有机化工企业废水中去除率为12.05%，甘蔗渣PAC在涂料工业废水中为10.85%；铁方面，椰壳PAC在涂料工业废水中去除率为18.69%，甘蔗渣PAC为14.24%；铬方面，椰壳PAC在有机化工企业废水中去除率为21.00%，甘蔗渣PAC在Petlad污水处理厂废水中为45.38%；钙方面，椰壳PAC在Vallabh Vidyanagar污水处理厂废水中去除率为22.86%，甘蔗渣PAC在Petlad污水处理厂为40.00%；镁方面，椰壳PAC在有机化工企业废水中去除率为18.61%，甘蔗渣PAC在Petlad污水处理厂为47.20%；氯化物方面，椰壳PAC在有机化工企业废水中去除率为60.00%，甘蔗渣PAC为85.08%。

对所选工业废水的对比研究显示：椰壳PAC对涂料工业废水中硫酸盐的去除率为97.28%，甘蔗渣PAC为92.65%；对Vallabh Vidyanagar污水处理厂废水中硫酸盐的去除率分别为92.13%与94.29%；对Petlad污水处理厂废水中硫酸盐的去除率分别为92.13%与92.46%；对有机化工企业废水中，椰壳PAC对硫酸盐去除率为63.71%，甘蔗渣PAC对氯化物去除率为85.08%。

实验结束后发现，椰壳PAC对涂料工业废水中硫酸盐的去除效果最优（97.28%），其次为Vallabh Vidyanagar及Petlad污水处理厂废水（均为92.13%），有机化工企业废水为63.71%。而甘蔗渣PAC对Vallabh Vidyanagar污水处理厂废水中硫酸盐的去除效果最佳（94.29%），其次为涂料工业废水（92.65%）、Petlad污水处理厂废水（92.46%），并可去除有机化工企业废水中85.08%的氯化物。总体而言，相较于甘蔗渣PAC（94.29%），椰壳PAC对涂料工业废水中硫酸盐的去除效果更为稳定（97.28%）。值得注意的是，甘蔗渣PAC可实现对有机化工企业废水中氯化物的专属高效去除（85.08%）。

本研究结果表明，椰壳与甘蔗渣基植物基活性炭可高效去除废水中的营养盐与重金属，且可将天然植物废弃物转化为适用于多规模工业废水处理的实用吸附材料。